Progress, Applications, and Challenges of Amorphous Alloys: A Critical Review

Abstract

Amorphous alloys, also known as metallic glasses, are a type of novel amorphous material discovered by chance. This discovery has greatly enriched the field of metal physics, spurred the rapid development of amorphous physics and materials science, and propelled amorphous physics to the forefront of condensed matter physics. As an important and challenging branch of this discipline, amorphous physics now plays a pivotal role in understanding the complexities of non-crystalline materials. Amorphous materials, characterized by their unique properties, are not only widely used in daily life and high-tech fields but also serve as model systems for studying significant scientific issues within materials science and condensed matter physics. This paper provides a comprehensive review of amorphous alloys, discussing major scientific issues and challenges in amorphous science, the formation mechanisms of these materials, their structural characteristics, and their physical and mechanical properties. Additionally, it explores the various applications of amorphous materials and forecasts future research trends, significant issues, development prospects, and directions within this vibrant field.

1. Introduction

Amorphous alloys, also known as metallic glasses or liquid metals, are novel materials synthesized using modern rapid solidification techniques [1]. These alloys combine the excellent mechanical, physical, and chemical properties of both metals and glasses. The term “metal” in metallic glass indicates that the material is made from metallic elements, while “glass” refers to its non-crystalline structure [1,2]. Theoretically, glass is a material that does not crystallize during the transition from liquid to solid. Typically, metal alloys crystallize upon cooling, with atoms arranged in an orderly manner to form crystalline metals like steel. However, rapid solidification prevents this, causing atoms to be “frozen” in a disordered state, thus creating a metallic glass [3]. On a microscopic level, metallic glass resembles a highly viscous liquid, also called “frozen melt”. Common glassy materials like plastics, glass, rosin, paraffin, asphalt, and rubber share a disordered atomic or molecular arrangement. If the atomic arrangement of crystalline solids like steel is akin to a well-ordered parade, the arrangement in amorphous solids is like a bustling crowd on a busy street. Ordinary window glass is made from elements like silicon and oxygen; plastics are polymeric glasses, and metallic glasses are metal alloys composed of different metallic elements. For example, zirconium-based metallic glass is synthesized from zirconium, copper, aluminum, and titanium. Due to its unique structure, metallic glass exhibits excellent mechanical, physical, and chemical properties [4].

The discovery of glass dates back to around 3000 BC in ancient Babylon, indicating a long history. However, metallic glass appeared much later [5]. In 1960, Professor Duwez from the California Institute of Technology reported the discovery of an amorphous structure in a rapidly solidified Au₇₅Si₂₅ alloy in a brief paper in Nature [6]. This sparked extensive research into amorphous alloys, leading to the commercial production of amorphous alloy ribbons and wires by Chen and colleagues in 1971 using melt spinning techniques (Hofmann, 2013). These alloys, known for their excellent soft magnetic properties, were widely used in transformer cores [7]. Early preparation techniques and limited alloy compositions restricted amorphous alloys to thin ribbons or wires, limiting their commercial application [8]. In the 1970s, Chen and colleagues produced palladium-copper-silicon amorphous alloy rods using suction casting methods, achieving millimeter-scale diameters and marking the earliest bulk amorphous alloys (Hofmann, 2013). Since the 1980s, various bulk amorphous alloy systems with dimensions exceeding 1 mm have been developed [9]. Notably, in 1993, Johnson and colleagues developed bulk zirconium-based amorphous alloys reaching centimeter scales, significantly promoting commercial applications and initiating a second research wave [10]. In the 21st century, the development of amorphous alloys accelerated, achieving significant milestones [11]. For instance, in 2005, academician Wang Weihua’s team at the Institute of Physics, Chinese Academy of Sciences, developed metallic plastic, an amorphous alloy deformable like thermoplastic at around 90 °C but exhibiting metal characteristics at room temperature [11]. These properties enable researchers to imprint and mold amorphous alloys at suitable temperatures, fabricating nanoscale precision components unattainable with conventional crystalline alloys [12,13]. Despite only a 60-year history, amorphous alloys have seen significant theoretical and technological advancements [14], as summarized in Figure 1.

Amorphous alloys and their composites, known for their excellent properties (see Section 4), have broad applications in modern science and technology. These alloys are free from defects such as dislocations and grain boundaries, which are common in crystalline materials, and possess a super-high elastic limit. This makes them particularly well-suited for use in micro-electromechanical systems (MEMSs) [16]. For instance, the Pd-Cu-Si amorphous thin film micro-spring is utilized as a trigger in MEMS devices [16]. Additionally, the softening behavior observed in the supercooled liquid region of Zr-based amorphous alloys facilitates the easy manufacturing of complex-shaped precision components, such as those found in consumer electronics [17]. The abundance of active sites on the surfaces of amorphous alloys is leveraged in high-performance catalysts, exemplified by the Fe-Si-B-Nb thin film used for azo dye degradation [18]. Furthermore, the isotropic chemical properties of these alloys enable uniform chemical corrosion and dissolution, making them ideal for aerospace applications. A notable example is the Zr-Nb-Cu-Ni-Al amorphous alloy coating on the solar wind particle collection panel of NASA’s Genesis spacecraft [19]. Finally, the ultra-high elastic limit of amorphous alloys enhances their suitability for sports equipment, like the Zr-based alloy baseball bat, which offers high energy transfer efficiency [20].

In recent years, researchers have discovered that amorphous alloys excel at suppressing harmonic vibrations compared to other metal materials. This ability effectively controls the reflection of noisy sound waves, resulting in a darker sound background, a stronger sound base, and excellent intrinsic low-frequency attenuation [20]. These properties also ensure good energy transmission, leading to fuller and more mellow sound, especially in the mid-frequency vocal range. Due to these outstanding acoustic properties, amorphous alloys have found significant applications in acoustics. For instance, Zr-based amorphous alloys have been used in headphone components by Sony (released in 2018) and for fixing pins in string instruments by Martin Guitar (released in 2015). Furthermore, amorphous alloys exhibit excellent forming properties in the supercooled liquid region, coupled with ultra-high strength, hardness, and wear resistance after cooling and solidifying. These characteristics make them ideal for creating high-precision, high-conformity, and strong creep-resistant components that are challenging to produce with conventional crystalline materials. Notable examples include the car door lock cover by Tesla (released in 2015) and the foldable phone hinge by Huawei (released in 2020) [20]. In addition to these applications, the largest use of amorphous alloys is in soft magnetic amorphous materials, such as transformer core materials. Transformer cores made from soft magnetic amorphous alloy materials achieve an energy conversion efficiency of 99.3%, compared with 97% for the best soft magnetic crystalline alloys [21]. With ongoing research, the potential application range of amorphous alloys is expected to expand significantly [22,23,24].

2. Formation and Production of Amorphous Alloys

2.1. Conditions for the Formation of Amorphous Alloys

• Fundamental Principles of Amorphous Alloy Formation

(1)

Cooling Rate and Glass-Forming Ability (GFA)

The formation of amorphous alloys primarily depends on the cooling rate. Different substances require vastly different cooling rates to form an amorphous state. For example, SiO₂ can form a glassy state at a cooling rate lower than 10⁻³ K/s, whereas many metals and alloy systems struggle to form an amorphous state even at a cooling rate of 10¹⁰ K/s. The ability to form an amorphous state is typically characterized by the critical cooling rate (RR_c) [25]. Studies have found that even for metallic systems, the difference in their forming ability can be more than 12 orders of magnitude. Generally, amorphous alloys with a critical size greater than 1 mm are called bulk amorphous alloys [26,27,28].

$$R{R}_C={\displaystyle \frac{dT}{dt\left(\frac{K}{s}\right)}}=10/D^2\left(\mathrm{cm}\right)$$

where D is the critical size.

The critical size refers to the maximum size of a bulk amorphous alloy that can be formed. Generally, amorphous alloys with a critical size greater than 1 mm are referred to as bulk amorphous alloys. The GFA of an alloy system can be measured by determining the maximum size of the bulk amorphous alloy that can be formed. Systems with good GFA can form amorphous alloys at relatively slow cooling rates and achieve larger critical sizes. To summarize, GFA measures the ease with which an alloy can be transformed into an amorphous state. It is influenced by the cooling rate required to prevent crystallization and the critical size of the alloy that can be produced in an amorphous form. Materials with high GFA can form amorphous structures at lower cooling rates and achieve larger critical sizes, making them suitable for forming bulk amorphous alloys.

(2)

Thermodynamic Conditions

The formation of an amorphous state is closely related to the thermodynamic conditions of the substance. During the cooling process of a high-energy liquid, if the free energy is lower than that of the crystalline phase and the system can overcome the nucleation barrier, an amorphous state may form. This formation is a metastable phenomenon, where the free energy of the liquid or amorphous state is higher than that of the crystalline state within a certain temperature range, but due to kinetic reasons, the amorphous state persists [29].

(3)

Kinetic Factors

The kinetic conditions for forming an amorphous state include avoiding crystal nucleation and growth during the cooling of the liquid metal. Turnbull’s research indicates that liquid metals can be supercooled far below the equilibrium melting point without nucleation and growth [30]. In supercooled liquids, the nucleation rate and growth rate of crystals are crucial for forming an amorphous state. A key indicator of amorphous formation is sufficiently low nucleation and growth rates in the supercooled liquid, allowing it to maintain a disordered state [31].

b.

Specific Conditions for Amorphous Alloy Formation

(1)

Chemical Bonding Characteristics

The formation of amorphous alloys is closely related to the chemical bonding characteristics of the substance [32]. The type and strength of chemical bonds determine key parameters such as melting point, rheological properties, and viscosity coefficient. For example, substances with covalent and ionic bonds form network structures, which have high viscosity and favor the formation of amorphous states. Additionally, electronegativity affects the glass-forming ability; oxides composed of atoms with low electronegativity are difficult to form into an amorphous state.

(2)

Atomic Size and Composition

Differences in atomic size and compositional complexity in alloy systems significantly affect the glass-forming ability. Egami’s research suggests that when the atomic size difference between components exceeds 12%, it promotes a densely packed random atomic structure, enhancing the glass-forming ability [33]. Moreover, multi-component alloy systems with complex compositions have a high nucleation barrier, significantly increasing the tendency to form an amorphous state.

(3)

Thermodynamic and Kinetic Stability

Methods to enhance the stability of amorphous alloys include increasing the crystallization temperature and the glass transition temperature, thereby achieving a wide supercooled liquid region. Alloy systems should possess high diffusion or nucleation barriers to maintain the stability of the amorphous state over a wide temperature range.

2.2. Rapid Solidification Techniques

Typical gas-phase processes include vapor deposition, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD) [34]. The amorphous alloys prepared by vapor deposition are mostly thin film samples. A popular vapor deposition technique is ion beam sputtering deposition, a type of PVD [35]. This process uses a high-energy particle beam, such as an argon (Ar) ion beam, to bombard the target material’s surface atoms, causing them to detach from the target. The detached atoms then deposit on a cold substrate to form an amorphous alloy film [26]. Due to the direct condensation from the vapor phase to the solid phase, this process achieves a cooling rate of up to 10¹³ Ks⁻¹. At such high cooling rates, many metals and their alloys can avoid crystallization and form amorphous alloys, and even pure metals can form pure amorphous states [35,36]. As an example, Wang et al. successfully prepared an amorphous iridium-nickel-tantalum (Ir-Ni-Ta) alloy film hydrogen evolution catalyst with high intrinsic activity using ion beam sputtering deposition [37]. The ion beam sputtering deposition technique they used is shown in Figure 2, which also illustrates the auxiliary ion source generally used for cleaning the deposited substrate.

There are various methods for preparing amorphous alloys through liquid processes, such as rapid solidification of alloy melts [38] and electrochemical deposition [39]. Common laboratory methods for preparing amorphous alloys through liquid processes include melt spinning, copper mold suction casting, and spray casting [40]. In the melt spinning process, the alloy is first melted into a liquid state through induction melting, then rapidly ejected onto a high-speed rotating copper wheel by applying pressure with an inert gas. This causes the melt to rapidly solidify and form an amorphous state before crystallization can occur [41]. In the spray casting process, the alloy is also first melted and then rapidly ejected into a cooled copper mold by applying pressure with an inert gas, forming an amorphous state. By altering the internal shape of the mold, the ability of the alloy system to form bulk amorphous alloys can be measured, i.e., the maximum size of the bulk amorphous alloy that can be formed [35]. In the copper mold suction casting process, the alloy ingot is melted into a liquid state through arc melting in a mold with small holes of different diameters at the bottom. Due to surface tension, the alloy melt typically does not automatically drop into the mold. A mechanical pump at the bottom of the mold generates a certain suction force to draw the alloy melt rapidly through the mold holes into the mold, where it is quickly solidified into an amorphous alloy [35].

The core of these liquid processes for preparing amorphous alloys is the cooling rate of the liquid melt. Typically, the melt spinning process can achieve a cooling rate on the order of 10⁶ Ks⁻¹, while the cooling rate in the copper mold casting process is much lower, around the order of 10³ Ks⁻¹ [36]. Therefore, these methods have limited cooling rates and are restricted by the glass-forming ability of the alloy systems. Generally, only alloy systems with good glass-forming ability can be prepared into an amorphous state using these methods, such as certain Zr-based (e.g., Zr₆₅Cu₁₇.₅Ni₁₀Al₇.₅) and Pd-based (e.g., Pd₄₀Cu₃₀Ni₁₀P₂₀) alloy compositions [35]. For systems with exceptionally good glass-forming ability, such as the aforementioned Pd-based systems, even a simple water-quenching process of the melt can result in an amorphous state [42].

Electrochemical deposition offers another method for preparing amorphous metals or alloys via liquid processes. In the electrochemical deposition process, metals or alloys containing the desired elements are deposited through electrochemical reduction reactions from a precursor solution containing these elements. Theoretically, even pure metals with poor glass-forming ability can form an amorphous state using this method [43]. In fact, as early as 1950, Brenner et al. first used electrochemical deposition to prepare a series of phosphorus (P)-containing cobalt (Co) and nickel (Ni) alloys and reported that the X-ray diffraction pattern of a high-Ni-content P-containing alloy sample showed only a diffuse pattern, suggesting a possible amorphous phase [44]. Unfortunately, the authors did not provide the X-ray spectrum in their report, nor the exact composition of the alloy. Nevertheless, Brenner‘s work indicated the feasibility of preparing amorphous alloys through electrochemical deposition.

In recent years, Wang et al. reported a method for in situ electrochemical deposition of amorphous metals in button cells, which can even produce amorphous lithium (Li), a highly active metal [45]. A schematic diagram of this method is shown in Figure 3. Figure 3a illustrates a Li metal battery device, which includes a Cu current collector (for drawing out the negative current), a Li metal anode, electrolyte, separator, a Li transition metal oxide cathode, and an Al current collector (for drawing out the positive current). During the battery cycling process, lithium ions (Li⁺) shuttle between the cathode and anode is driven by the internal electric field, undergoing electrochemical deposition on the electrodes. Figure 3b shows a schematic of Li⁺ undergoing electrochemical deposition on the Li metal anode. With a reasonable device design and appropriate electrochemical deposition conditions, the amorphous metal Li can be obtained [45]. Although this in situ electrochemical deposition method often yields only a very small amount of amorphous metal in a single experiment, and the sample preparation and transfer process is rather cumbersome, it represents a significant advancement in the preparation of highly active metals in an amorphous state. Typical cooling rates for these techniques can range from a few 10³ K/s for copper mold casting up to several thousand 10⁶ K/s for melt spinning processes. Other techniques, such as electrochemical deposition and mechanical alloying, do not directly specify cooling rates but involve conditions that promote the formation of amorphous phases.

2.3. Other Production Methods

There are many methods for preparing amorphous alloys through solid-state processes, such as irradiation-induced amorphization [47], deformation-induced amorphization [48], and the rolling process [49]. However, the most commonly used method is mechanical alloying [1]. The basic principle of mechanical alloying is to induce severe deformation in the mixed metal powders through mechanical means. This process increases the defect content in the system and raises the Gibbs free energy, facilitating the transition from a stable state to a metastable state, such as the transformation from mixed elemental metal powders to amorphous alloy powders [50], as illustrated in Figure 4.

Thin film metallic glasses (TFMGs) are typically prepared using deposition techniques such as physical vapor deposition (PVD) and sputtering, which allow for high-quality amorphous films with uniform thickness [51]. These films exhibit superior mechanical properties compared to bulk metallic glasses, including higher strength and increased ductility. At the nanoscale, TFMGs can attain ceramic-like strengths and metal-like ductility simultaneously without the catastrophic failure associated with bulk materials. The reduction in size limits the formation of shear bands, promoting homogeneous deformation [52]. This section provides an overview of deposition techniques, unique film architectures, and their applications, focusing on their mechanical behavior. Pulsed Laser Deposition (PLD) is a powerful technique for synthesizing ultrafine nanolaminates (U-NLs) with precise control over local heterogeneities. PLD allows the creation of novel crystal/glass U-NLs, such as structures with ~4 nm thick crystalline Al layers separating 6 and 9 nm thick Zr₅₀Cu₅₀ glass nanolayers. This technique achieves a high density of sharp interfaces and significant chemical intermixing. Compact U-NLs, grown atom-by-atom, exhibit high mass density (~8.35 g/cm³) and enhanced mechanical properties, including hardness and yield strength up to 9.3 and 3.6 GPa, respectively. In contrast, nanogranular U-NLs, formed via cluster-assembled growth, show slightly lower yield strength (3.4 GPa) but enhanced elastoplastic deformation (~6%) [53]. Multilayer films, consisting of alternating layers of different materials, provide unique opportunities to tailor the mechanical and functional properties of metallic glasses. These films can control shear band nucleation and propagation, resulting in improved strength and ductility. Nanogranular films featuring nanometer-sized grains dispersed in an amorphous matrix exhibit exceptional mechanical properties such as high hardness and wear resistance. These films are particularly promising for microelectronics and coatings applications. Their formation mechanisms and properties suggest significant potential in microelectronics, particularly in MEMS and NEMS devices, where high-performance electronic components are essential. In the coatings industry, TFMGs offer excellent corrosion and wear resistance, making them ideal for protective coatings in aerospace and automotive applications [54]. The robust properties of these films are crucial for industries requiring durable and long-lasting materials. The combination of high hardness, yield strength, and elastoplastic deformation makes TFMGs suitable for environments where mechanical stress and exposure to harsh conditions are common. In conclusion, the deposition techniques and unique architectures of TFMGs enable the development of materials with superior mechanical properties and a wide range of applications. The advancements in PLD and the exploration of compact versus nanogranular films highlight the versatility and potential of TFMGs in various high-tech industries.

It should be noted that the product obtained from the mechanical alloying process is usually amorphous alloy powder, which often requires further processing to achieve the desired final product. The most common method for achieving mechanical alloying is high-energy ball milling. In this method, pure metal elemental powders or pre-alloyed powders in specific proportions are mixed with quenched steel balls or hard alloy balls in a certain ratio and placed in a ball mill jar. The jar can be filled with a specific atmosphere or vacuum. The prepared jar is then mounted on a ball mill, and the milling parameters, such as rotation speed and milling time, are set according to the desired outcome. Ultimately, the required amorphous alloy powder can be obtained [50]. Figure 5 shows a planetary high-energy ball mill and its ball mill jar.

3. Structure and Properties

3.1. Description of the Atomic Structure of Amorphous Alloys

The earliest structural models of amorphous alloys may originate from studies on the structure of liquids. Specifically, early explorations of mathematical and physical models of liquid structures by Bernal and colleagues at the University of Cambridge in the 1960s laid the foundation for qualitative structural models of amorphous alloys. A key point in this was the introduction of the concept of random close packing [55]. Because glass is also considered a “frozen liquid” [56], amorphous alloys, also known as glassy alloys or metallic glasses, naturally lend themselves to the application of the random close packing concept in their structural modeling. This involves modeling the structure of amorphous alloys using the random close packing of equal-sized hard spheres, which may be among the earliest studies on the structural models of amorphous alloys [53].

However, this model has several deficiencies. One significant issue is that it does not address the structure of amorphous alloys containing components of different sizes and concentrations. Additionally, the introduction of components of varying sizes and concentrations makes the model analysis extremely difficult. Furthermore, the nearest neighbor coordination in this model is similar to the crystalline phase, seemingly not meeting the requirements of randomness and being difficult to extend beyond the nearest neighbor coordination shell to obtain the medium-range order discovered later in amorphous alloys [57].

From 2004 onwards, Miracle et al. further proposed and gradually refined the cluster-dense packing model for amorphous alloys [57,58,59,60], as shown in Figure 6. In this model, the authors proposed that the basic units for constructing the structure of amorphous alloys are not the atoms of the components themselves but clusters centered around solute atoms that can pack effectively, such as FCC and HCP clusters, which are favorable because they can most efficiently fill space [60]. These clusters, as basic units, can be idealized as spheres packed in three-dimensional space, filling the space [51]. The order of the solute forming the clusters does not extend beyond even a few cluster distances due to internal strain, thus not forming long-range order or orientational order [61]. Adjacent clusters share solvent atoms in a vertex-sharing, edge-sharing, or face-sharing manner, causing the clusters to overlap in the nearest neighbor coordination shell, with solvent atoms randomly occupying positions. From a topological perspective, regardless of the number of elements in the alloy, there are only three types of solutes, each with a specific size relative to the solvent, to produce effective atomic packing [57].

The schematic of this model is shown in Figure 6a,b. In the left part of Figure 6a, Ω represents solvent atoms (within the first shell), and the three types of solutes are α as the solute forming the primary cluster or the cluster center, β as the solute occupying the octahedral interstices of the cluster, and y as the solute occupying the tetrahedral interstices of the cluster (not illustrated in the Figure) [57]. From the perspective of structural sites, combining Ω, the cluster-dense packing model suggests that there are no more than four different types of sites (Ω, α, β, y) in the structure of amorphous alloys. The occupation of these sites can provide information on the minimum solute concentration for forming amorphous alloys [60]. If some sites are unoccupied, this corresponds to vacancies in the structure; if the solvent occupies solute sites, such as Ω occupying the α site, it forms antisite defects. The right part of Figure 6a shows the three-dimensional packing of solvents and various clusters. Here, α solutes are wrapped by pink solvents Ω, β solutes are purple spheres, and y solutes are orange spheres. Figure 6b shows a cluster organized in a hexagonal arrangement with vertex-sharing and face-sharing connections (bottom right inset). This packing method imagines the cluster as a sphere packing (spheroidal packing) to fill space. Since clusters are not true spheres, the gaps and contact modes between clusters (as shown in the bottom right inset) vary, causing distortions and deviations from the strict lattice form of HCP packing, resulting in an amorphous structure [21].

The cluster-dense packing model has achieved some theoretical and experimental successes. First, the structure of amorphous alloys can be constructed purely from topology (relative sizes and number of components), involving no more than four topologically different sites: Ω, α, β, and y or one solvent Ω and three solutes α, β, and y (only three topologically different ones) [57]. Depending on the packing of clusters, defects may appear in the structure, such as vacancies like β, y vacancies, and antisite defects like Ω occupying the α site. This construction links the static structural model to some dynamic processes in amorphous alloys, such as diffusion and relaxation. Second, early structural models of amorphous alloys could not explain the physical origin of short-range order and medium-range order. The cluster-dense packing model provides a simple and intuitive physical origin for these orders: the clusters as basic structural units are themselves short-range ordered, consistent with the short-range order in crystalline alloys of the same composition as amorphous alloys, such as FCC and HCP clusters. Short-range order is highly sensitive to topology, electronic structure, and even minor compositional changes, controlling the formation and stability of amorphous alloys, which tend to crystallize into crystalline phases with the same local order (including short-range and medium-range order) as corresponding crystalline alloys [57]. Medium-range order is formed by the spatial organization of overlapping clusters, with the medium-range order scale predicted by the cluster-dense packing model being about 1 nm [58,61]. Third, experimental characterization has found that the density of amorphous alloys is often only about 0.5% lower than that of crystalline alloys of the same composition [21], indicating a very high atomic packing efficiency in amorphous alloys. The density of amorphous alloys obtained from the cluster-dense packing model matches well with experimentally measured densities. Furthermore, the compositions of many early binary amorphous alloys and the diffraction experimental results of the short-range and medium-range order they contain also match the predictions of the cluster-dense packing model [62]. However, the cluster-dense packing model is not yet perfect. As pointed out by the original authors of the model, it is not entirely predictive and still requires quantitative descriptions of chemical interactions to determine how topologically equivalent but chemically significantly different solutes enhance or inhibit the stability of amorphous alloys [57]. Additionally, the packing fractions given by the model are sometimes unrealistically high, which is another shortcoming [21].

This section mainly reviews two typical structural models proposed during the study of amorphous alloy structures. In fact, researchers have proposed various structural models for amorphous alloys, but they generally revolve around sphere packing (including later-developed soft sphere packing) and cluster packing [63]. Currently, there is no consensus on the structure of amorphous alloys, and many different structural models exist for different amorphous alloy systems. These models can be effective in solving specific system problems but still have many shortcomings in quantitative descriptions [63]. Solving the structural issues of amorphous alloys remains a challenging and long-term task.

3.2. X-ray Diffraction and Transmission Electron Microscopy Analysis

X-ray diffraction (XRD) techniques and their derivative methods have been extensively utilized to investigate various aspects of amorphous alloys. These techniques range from confirming the amorphous state to analyzing the microstructure, such as short-range order, medium-range order, and coordination number, as shown in Figure 7. Figure 7a presents the conventional XRD spectrum of the Ir-Ni-Ta amorphous alloy system, which is frequently used in contemporary laboratories to preliminarily confirm the amorphous state of samples. Figure 7 confirms that a series of Ir-Ni-Ta amorphous alloys are indeed amorphous [64]. Moreover, conventional XRD spectra can also reflect specific local structural information. For instance, Figure 7b shows the conventional XRD spectra of a set of Al_(90-x)Ni₁₀Cex (x = 3, 5, 6, 8) amorphous alloys. Besides the main peak, a distinct prepack appears on the low-angle side of the XRD spectra. The original authors attributed this to the medium-range ordered cluster structure related to cerium (Ce) in these amorphous alloys [65]. It is worth noting that the original image of this Figure lacks units on the horizontal axis 2θ, which might have been omitted in the original text. However, this omission does not affect the interpretation of Figure 7.

With the continuous development of synchrotron radiation technology, various X-ray techniques based on synchrotron radiation can also effectively characterize the structure of amorphous alloys [66,67,68]. In addition to the more common high-energy synchrotron XRD, techniques such as Extended X-ray Absorption Fine Structure (EXAFS) [69] and X-ray Cross-Correlation Analysis (XCCA) [70] are also employed, as shown in Figure 8. Figure 8 displays the EXAFS spectra at the Cu-K and Zr-K absorption edges (left) and their corresponding Fourier transform spectra (right) for Cu₅₀Zr₅₀, Cu₄₅Zr₄₅Ag₁₀, and Cu₄₀Zr₄₀Ag₂₀ amorphous alloys [69]. These spectra reveal the variations in the nearest-neighbor coordination of Cu and Zr in three different compositions of amorphous alloys. For example, the Cu-K edge spectra of Cu₅₀Zr₅₀ and Cu₄₅Zr₄₅Ag₁₀ in the upper section almost overlap, indicating that the addition of 10 at.% silver (Ag) hardly affects the nearest-neighbor coordination of the Cu shell [69]. However, the Cu-K edge absorption spectrum of Cu₄₀Zr₄₀Ag₂₀ differs significantly, showing splitting, which the authors attribute to possible phase separation in the sample [69]. The Zr-K EXAFS spectra in the lower section of Figure 8 show significant changes with the addition of Ag, especially on the low wavenumber side. The Fourier transform spectra on the right indicate that this change might be related to the inconsistency in peak intensity of the corresponding Zr-Zr atomic pairs. Since peak intensity is related to the number of neighboring atoms, and considering that the Cu-K EXAFS spectra of Cu₅₀Zr₅₀ and Cu₄₅Zr₄₅Ag₁₀ in the upper section show almost no change, the authors inferred that the addition of Ag selectively replaced some Zr-Zr atomic pairs with Zr-Ag atomic pairs [69]. Wochner P shows a schematic diagram of the XCCA technique apparatus. An incident coherent X-ray beam is collimated and then directed onto the sample, such as the colloidal sample shown in the figure, resulting in a two-dimensional diffraction pattern [70]. Through quantitative analysis (the diagram illustrates the construction of the cross-correlation analysis function), information about the local symmetry within the amorphous structure can be obtained. The diagram demonstrates the local five-fold symmetry (LFS) of PMMA (polymethyl methacrylate, also known as acrylic glass) spheres [70].

Despite the significant convenience and rich structural information provided by X-ray diffraction (XRD) techniques for characterizing amorphous alloys, certain limitations necessitate the supplementation of other characterization techniques. X-ray-based characterization techniques typically target the overall amorphous alloy sample and often record the intensity information of X-rays scattered by the sample during the experiment, lacking phase information. The results obtained from analyzing intensity information generally reflect the structural information of the entire sample as a statistical average [71]. Consequently, these techniques cannot provide more detailed atomic-level structures and local environments, such as the short-range and medium-range order in amorphous alloys.

Furthermore, the structural information extracted by characterization methods based on X-ray diffraction techniques, such as RDF (which reflects the correlation between two atoms or atomic pairs rather than multi-body correlations), often only indirectly reflects the statistical distribution of atomic distances and atomic coordination in amorphous alloys [72]. These methods cannot provide direct visual structural images. While X-ray-based characterization techniques can produce reconstructed images, their resolution is relatively low [73]. For instance, computer-assisted tomography (CT) can reconstruct microstructural images of materials based on X-ray tomography. However, the spatial resolution of CT is limited and cannot reveal the precise structural or chemical composition information of different regions. Even though the latest third-generation synchrotron radiation sources can produce intense and bright X-rays, allowing for relatively short acquisition times and dynamic CT, the resolution of the reconstructed images is constrained by the physical size of the X-ray beam used, typically in the micrometer range [74]. Advanced nano-CT (with X-ray beam sizes on the nanoscale) has a resolution of only a few tens of nanometers [73,75], which far exceeds the scale of characteristic local structures in amorphous alloys, such as medium-range order, which is approximately 5–20 Å [72]. This resolution is much larger than the scale of local structures in amorphous alloys, and even tiny nanocrystals cannot be detected by nano-CT.

Characterization techniques based on electron diffraction provide a highly resolved method for imaging typical local structures in amorphous alloys. Nowadays, advanced transmission electron microscopy (TEM) can achieve sub-angstrom resolution. TEM with spherical aberration correction can easily achieve atomic-level resolution, allowing the observation of phenomena such as the formation of metallic bonds between two metal atoms [76] and interstitial atoms in solid solutions [77]. TEM used for observing the structure of amorphous alloys can provide direct visual images, directly imaging various local orders [78], structural heterogeneities [79], and compositional fluctuations [80] in amorphous alloys.

In recent years, significant advances have been made in the study of the atomic-level structure of amorphous alloys, driven by advanced TEM characterization techniques. Around 2011, Chen and colleagues developed Aemi Beam Electron Diffraction (ABED) techniques, which are capable of directly observing short-range order, such as icosahedral order, in amorphous alloys, as illustrated in Figure 9 [81,82]. Figure 9a shows the ABED experimental setup, with a coherent electron beam diameter of 3.6 Å. This probe size is close to the characteristic local structures in amorphous alloys (typically, the short-range order in amorphous alloys is believed to be 2–5 Å, medium-range order is 5–20 Å, and the long-range order is over 20 Å [10]), enabling the direct detection of these local structures. Figure 9b presents diffraction patterns in the 2-, 3-, and 5-fold symmetry axis directions of an ideal icosahedron from molecular dynamics simulations. The original literature notes that the experimentally observed diffraction patterns in these directions retained only part of the corresponding axial symmetry of the ideal icosahedron. The discrepancy between experimental and simulated results is attributed to some distortion in the observed icosahedrons. When using distorted icosahedrons for simulation, the results closely match the experimental observations, as shown in Figure 9c [81]. Breakthroughs in advanced aberration-corrected electron microscopy, data acquisition, three-dimensional image reconstruction, and atomic tracking algorithms have made atomic electron tomography (AET) a more powerful tool for characterizing the structure of materials.

By collecting projection images of the sample from multiple directions and combining them with computer-aided reconstruction [83], as shown in Figure 10, AET can determine the three-dimensional grain boundaries of crystalline materials, the three-dimensional structure of dislocation core, and track the coordinates of individual atoms within the sample [83].

Atomic Electron Tomography (AET) has significantly advanced the determination of the three-dimensional atomic structure of amorphous alloys by enabling the tracking of individual atomic coordinates. In 2021–2022, researchers such as Yang [84] and Yuan [85] utilized this technology to map the three-dimensional atomic structures of multi-component (Co, Ni, Ru, Rh, Pd, Ag, Ir, Pt) amorphous nanoparticles, pure Ta amorphous films, and pure Pd amorphous nanoparticles, as illustrated in Figure 11. Figure 11a,b showcase the AET three-dimensional reconstructed images of the multi-component amorphous nanoparticles and the four typical medium-range ordered atomic packing configurations within them. In Figure 11a, due to the limitations of current AET technology, only three types of atoms in the multi-component amorphous nanoparticles can be distinguished: Type1 (Co or Ni), Type2 (Ru or Rh or Pd or Ag), and Type3 (Ir or Pt). Consequently, the reconstructed image displays only these three types of atomic coordinates [84]. Figure 11b illustrates four medium-range ordered structures found in the amorphous nanoparticles: FCC-like, HCP-like, BCC-like, and SC-like atomic packing states, containing 22, 14, 11, and 23 solute centers (large red spheres), respectively. These single solute-centered clusters (dashed circles) are randomly distributed. On the right side of these medium-range ordered structures, the quasi-lattice arrangements of solute-centered atoms along specific axial directions are shown after the removal of solvent atoms, though they significantly deviate from ideal lattice structures [84]. Figure 11c displays the AET three-dimensional reconstruction results of pure Ta amorphous films and Pd amorphous nanoparticles. The gray areas on the surface represent some crystal nuclei. Figure 11d depicts the multiple tetrahedral packing of atoms in these two pure amorphous substances, with the tetrahedral centers indicated by small black spheres. The connections between tetrahedral centers form triangular, quadrilateral, pentagonal, and hexagonal bipyramidal configurations [85], with brown spheres representing capping atoms.

These studies experimentally confirm the pervasive presence of short-range order in amorphous alloys and pure substances, as well as the formation of medium-range order through the interconnection of these short-range ordered superclusters [84]. The experimental results also partially validate the dense cluster packing model of the amorphous alloy structure proposed by Miracle and others [59]. Additionally, the AET reconstructed atomic structures highlight the inherent compositional and structural heterogeneity of amorphous alloys.

4. Physical and Chemical Properties

4.1. Mechanical Properties

Mechanical properties are key indicators for structural materials, and amorphous alloys have set numerous records for the mechanical properties of metal materials, such as the highest elastic limit [19], highest fracture strength [86], and highest fracture toughness [87]. Amorphous-nanocrystalline composites can even achieve superior mechanical properties [88], with some summarized in Figure 12. Due to the structural defects in amorphous alloys being confined to a few atomic dimensions, they do not exhibit the typical slip along specific planes seen in crystalline materials under external forces. This results in unique deformation behavior and mechanical property characteristics. High strength is the most notable mechanical property of amorphous alloys. For example, the fracture strength of bulk amorphous alloys can reach 1023 MPa for Mg-based [89], 2083 MPa for Ti-based [90], 2477 MPa for Zr-based [91], 3542 MPa for Ni-based [92], and 3280 MPa for Fe-based alloys [93]. Notably, the fracture strength of Co-based amorphous alloys is even more remarkable, with reports indicating that Co₄₃Fe₂₀Ta₅.₅B₃₁.₅ can reach 5185 MPa [94], whereas the strength of crystalline materials of the same alloy system is only a fraction or even a tenth of that of amorphous alloys.

Similarly, the resistance of amorphous alloys to indentation by hard objects is much higher than that of their crystalline counterparts. For instance, the Vickers hardness of Fe₄₁Co₇Cr₁₅Mo₁₄C₁₅B₆Y₂ [19] can reach 12.53 GPa, while the hardness of ordinary crystalline iron alloys is only about 0.2 MPa. The elastic modulus is an important physical quantity that describes the elasticity of a material, and it varies with the system and composition. Although the elastic modulus of amorphous alloys is lower than that of their crystalline counterparts, their elastic strain is around 2%, more than four times higher than that of high-carbon spring steel. Additionally, due to their high elastic limit, bulk amorphous alloys have a very high elastic specific energy.

Fracture toughness reflects the ability of a material to resist crack instability and propagation, which is crucial for the strength design of components. With the continuous optimization of the composition of amorphous alloys, their fracture toughness has significantly improved. For example, the fracture toughness of Zr-based [95] amorphous alloys reached 86 MPa·m^1/2. Early amorphous alloys exhibited inhomogeneous strain under external forces, making fatigue cracks prone to nucleation under fatigue stress, resulting in lower fatigue life compared with traditional crystalline materials. This is mainly reflected in the differences in fatigue stress and cycle numbers. However, with continuous efforts by researchers, the fatigue properties of some bulk amorphous alloys have reached levels similar to traditional crystalline materials. For example, Gilbert [96] studied the crack propagation behavior of Zr-Ti-Cu-Ni-Be amorphous alloys and found that the stress range applied in this system determined the crack propagation rate. The load ratio had a similar effect to crack closure, and the fatigue fracture surface exhibited fatigue cracks similar to those in ductile metals.

4.2. Thermal Properties

The temperature range between the glass transition temperature (Tg) and the crystallization temperature (T_x) is referred to as the “supercooled liquid region”. In this region, amorphous alloys exhibit high viscosity and varying degrees of superplastic deformation behavior [97]. These characteristics enable the forging and extrusion of amorphous alloys to produce micro gears and precision instrument components. One of the most prominent features of amorphous alloys is their excellent magnetic properties. Due to the absence of grain boundaries, there are no obstacles, such as precipitated phase ions, to pin the domain walls, making amorphous alloys with soft magnetic properties easy to magnetize and extremely low coercivity. Additionally, the higher electrical resistivity in amorphous alloys can significantly reduce eddy current losses associated with changes in the direction of magnetic domains. In terms of electrical properties, the long-range disorder of atomic arrangement in amorphous alloys enhances their ability to scatter electrons. At room temperature, their resistivity is generally 100–300 μΩ·cm, which is 2–3 times that of traditional crystalline alloys. Furthermore, the resistivity of amorphous alloys is less affected by temperature, resulting in a smaller temperature coefficient of resistivity compared to crystalline alloys.

4.3. Chemical Properties

Amorphous alloys exhibit high corrosion resistance due to the absence of defects in their structure and lack of compositional segregation. This results in a uniform atomic structure and chemical composition, leading to widespread application. Studies have shown significant hydrogen absorption capabilities in amorphous alloys, especially Mg-based alloys with a hydrogen adsorption ratio close to 100% [98]. When used as electrode materials, Pd-based amorphous alloys demonstrate a strong ability to generate chlorine gas, with minimal material consumption after 500 cycles, less than one-tenth of that seen in general electrode materials, which degrade significantly after 20 or fewer cycles [99]. The passivation film formation rate in amorphous alloys is faster and more uniform compared with crystalline alloys. Gao [100] studied Ca-Mg-Zn series amorphous alloys, finding that their bioabsorbable element composition makes them suitable for use as absorbable materials in orthopedic surgery. Guo [101] investigated the corrosion resistance of Zr₆₂.₃Cu₂₂.₅Fe₄.₉Al₆.₈Ag₃.₅ amorphous alloy in artificial seawater using electrochemical methods, concluding that Zr-based amorphous alloys exhibit lower corrosion current density and potential.

5. Applications

5.1. Aerospace Industry

Amorphous alloys will have important applications in high-tech fields, which can mitigate their high cost while fully utilizing their unique properties. For example, amorphous alloys are considered essential candidate materials in the aerospace industry. The elastic deformation behavior of amorphous alloys is particularly significant for key structural materials that rely on elastic energy deployment. The elastic deformation of amorphous alloys can reach up to 2%, and their current maximum elastic limit exceeds 5000 MPa. Among lightweight amorphous alloys, titanium-based variants have an elastic limit exceeding 2000 MPa, which is unattainable by conventional crystalline and polymer materials. Recently discovered single-phase amorphous alloys with tensile strengths greater than 1.5 GPa and fracture toughnesses up to 200 MPa√m represent the highest fracture toughness among materials, achieving a perfect combination of high strength and high toughness. Therefore, amorphous alloys can meet the stringent performance requirements of large deployable structures in spacecraft. NASA collaborated with Professor Johnson’s research group at the California Institute of Technology shortly after the discovery of bulk amorphous alloys to develop high-hardness, high-specific-strength amorphous alloy foam materials. They also utilized the chemical homogeneity of amorphous alloys for solar wind collector materials [102].

5.2. Biomedical Engineering

Another important characteristic of amorphous alloys is their biocompatibility, degradability (such as in Ca- and Mg-based amorphous alloys), and non-allergenicity. These properties make them suitable for medical applications, including repairing implants and manufacturing surgical devices like surgical knives, artificial bones, biosensing materials for electromagnetic stimulation within the body, and artificial teeth [103]. Biodegradable biomaterials for implantation in the body are advantageous because they can avoid the need for secondary surgeries to remove the implant and prevent biological rejection issues associated with permanent implants. Mg-based amorphous alloys, due to their degradability, high strength, and elastic modulus close to that of bone, have the potential to become the next generation of materials for internal scaffolds. Thus, Mg-based amorphous alloys hold great promise in the field of biodegradable biomaterials.

5.3. Electronics and Energy Technology

The most mature and widely used application of amorphous alloys is in the field of amorphous magnetism [103]. Fe-, Ni-, and Co-based amorphous alloy ribbons have found extensive applications due to their excellent soft magnetic properties. These ribbons have become the ideal core materials for various transformers, inductors, sensors, magnetic shielding materials, and radio frequency identifiers. They are now indispensable fundamental materials in the fields of power, power electronics, and electronic information, with their manufacturing technology being quite mature.

Recently, Tohoku University in Japan developed various ferromagnetic bulk amorphous alloys and prepared toroidal magnetic cores using copper mold casting. These bulk amorphous alloys exhibit high magnetic saturation strength, high permeability, low coercivity, and low saturation magnetostriction, making their soft magnetic properties far superior to those of traditional silicon steel sheets and conventional crystalline magnetic materials [103]. It is anticipated that these materials will soon be applied in the rapidly developing electronic information sector, including computers, networks, communications, and industrial automation.

Electronic devices in these fields extensively use light, thin, small, and highly integrated switching power supplies, which rely on high-frequency electronic technology. This necessitates that the soft magnetic cores of transformers and inductors are suitable for high-frequency applications. Bulk amorphous alloys, with their high saturation magnetic induction, high permeability, low loss, and ease of processing, can be directly cast or processed into micro-cores of various complex structures. These cores can then be made into transformers or inductors for use in various electronic or communication devices. Consequently, the application prospects and market potential for these materials are very broad.

6. Challenges and Future Perspectives

6.1. Scalability and Cost Issues in the Production of Amorphous Alloys

The production of amorphous alloys primarily relies on rapid cooling technologies, which are essential to prevent the formation of crystalline structures. This process requires complex and expensive equipment that is effective only within limited shapes and sizes, which significantly restricts the feasibility of large-scale production. Techniques such as investment casting and rapid solidification methods demand precise control over temperature and cooling rates to ensure the formation of amorphous structures. Any slight deviation in these parameters can cause crystallization, thereby compromising the material’s performance and reliability.

The high cost of amorphous alloys primarily arises from the expensive, high-purity raw materials required, such as titanium, zirconium, and nickel, and the complexity of the production process. The production process itself, notably the rapid cooling technologies, demands high energy consumption and precision equipment, thereby further escalating costs. Additionally, the strict requirements for precise control and specific environmental conditions during manufacturing can cause minor issues that significantly increase the scrap rate, thus driving up overall production costs.

6.2. Optimization of Crystallization Tendency and Thermal Stability

Amorphous alloys are susceptible to crystallization under certain conditions, particularly at high temperatures or during extended use. This crystallization process can significantly deteriorate the material’s properties, including strength, toughness, and corrosion resistance. Consequently, optimizing the resistance to crystallization in amorphous alloys has become a critical area of research. Adjusting the alloy’s composition and processing parameters has been shown to effectively enhance its resistance to crystallization. For instance, incorporating a suitable amount of rare earth elements or employing a multi-component alloy design can inhibit the formation and growth of crystalline nuclei, thereby maintaining the desired amorphous structure.

Thermal stability in amorphous alloys refers to their capacity to retain their amorphous structure under high-temperature conditions. This property is essential for applications that involve high-temperature structural materials and electronic components. To enhance thermal stability, strategies such as optimizing alloy composition, utilizing heat treatment processes, and developing surface coatings that resist oxidation and corrosion have been employed. Furthermore, leveraging advancements in nanotechnology has led researchers to experiment with integrating nanoparticles or nanofibers into amorphous alloys, a method that promises to further boost their thermal stability.

6.3. New Alloy Design and High-Throughput Screening Techniques

• Challenges in New Alloy Design

Complexity of multi-element systems. Amorphous alloys are typically composed of multiple elements, resulting in complex compositions that render traditional trial-and-error methods inefficient. This complexity complicates the systematic optimization of alloy properties as the introduction of each new element can unpredictably affect the alloy’s structure and performance, adding uncertainty to the design process.

Balancing performance. In new alloy design, it is crucial to balance multiple performance indicators. For example, increasing strength might reduce toughness, while enhancing corrosion resistance could affect conductivity. Achieving this multi-objective optimization necessitates precise design and rigorous control, posing a significant challenge.

Limitations of theoretical models. The existing theoretical models, while useful, have limitations in guiding new alloy designs, particularly for complex multi-element systems. Accurately predicting an alloy’s glass-forming ability and physical properties continues to be a challenging endeavor.

b.

Advantages of High-throughput Screening Technology

Rapid screening. High-throughput screening technology facilitates the preparation and testing of numerous alloy samples with varied compositions simultaneously, significantly reducing the research cycle. This method swiftly identifies optimal composition combinations, thereby enhancing research efficiency.

Systematic research. This technology enables researchers to systematically examine the relationship between composition and performance, aiding in the creation of comprehensive databases. Such databases are crucial for uncovering patterns in alloy composition design and guiding the development of future materials.

Data-driven optimization. Integrating high-throughput screening with machine learning algorithms allows for the extraction of valuable insights from extensive experimental data, optimizing alloy design. For instance, machine learning algorithms can pinpoint potential high-performance alloy compositions from screening data, facilitating predictions and further optimizations.

7. Conclusions

7.1. Summary of Research Achievements and Technological Advances in Amorphous Alloys

Amorphous alloys, also known as metallic glasses, have garnered significant attention due to their unique properties and broad potential applications. The research and technological advancements in this field can be summarized as follows.

a. Historical milestones and production techniques. The first amorphous alloy was produced in 1960 at Caltech, which led to the discovery that rapid cooling (in the order of millions of degrees Celsius per second) is essential to prevent crystallization. Methods such as melt spinning, solid-state reactions, and mechanical alloying have been developed to produce amorphous metals. Advances in these techniques have allowed the production of bulk metallic glasses (BMGs) that can form thicker layers, improving their usability in various applications.

b. Material properties. Amorphous alloys exhibit superior mechanical properties, including high tensile strength, high elasticity, and excellent wear resistance compared with their crystalline counterparts. They also display unique electrical properties, such as high electrical conductivity and specific behaviors under temperature variations. Their magnetic properties make them suitable for applications like transformer cores and electronic article surveillance systems.

c. Applications. The special properties of amorphous alloys have been harnessed in various fields, including sports equipment, medical devices, and electronics. They are used in high-efficiency transformers, sensitive flow meters, pressure sensors, and more. Recent advances in 3D printing and other additive manufacturing techniques have enabled the creation of larger and more complex amorphous metal structures, expanding their potential uses.

7.2. Future Research Directions and Technological Challenges

Despite significant advancements, the field of amorphous alloys continues to face several challenges and opportunities for future research.

a. Enhanced production methods. Developing more efficient and scalable production techniques is crucial. Current methods require extremely rapid cooling rates, which limit the size and shape of the resulting amorphous metals. Innovations in additive manufacturing, such as selective laser melting (SLM) and laser foil printing (LFP), hold promise for overcoming these limitations, enabling the production of larger and more complex structures.

b. Material optimization. Research should focus on discovering new alloy compositions that can form glasses at slower cooling rates, making the production process more practical and cost-effective. There is a need to enhance the ductility and fatigue resistance of amorphous alloys to broaden their application range, particularly in reliability-critical fields.

c. Advanced applications. Exploring the use of amorphous alloys in biomedical applications, such as bioabsorbable implants, is a promising area. Alloys that dissolve in the body at controlled rates can revolutionize medical implants and fracture fixation devices. The development of amorphous alloys with superior properties, such as the highest recorded elastic limit, opens new possibilities in defense and aerospace for materials that can withstand extreme conditions.

d. Theoretical and computational modeling. Advanced computational models, leveraging artificial intelligence and machine learning, can accelerate the discovery of new amorphous alloy compositions and predict their properties more accurately. Theoretical studies on the electronic and atomic structures of amorphous metals will deepen the understanding of their unique behaviors and guide the development of new materials with tailored properties.

In conclusion, while the field of amorphous alloys has made significant strides, ongoing research and technological innovation are essential to fully realize their potential. Addressing production challenges, optimizing material properties, and exploring new applications will drive the future success of amorphous alloys in various industries.