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9 pages, 4077 KiB

Open AccessArticle

Effect of Minor Co Substitution for Fe on the Formability and Magnetic and Magnetocaloric Properties of the Amorphous Fe₈₈Ce₇B₅ Alloy

by Xu Zhou, Qiang Wang, Leling Pan, Ding Ding, Benzhen Tang, Peng Yu, Jinlei Yao and Lei Xia

Metals 2022, 12(4), 589; https://doi.org/10.3390/met12040589 - 30 Mar 2022

Cited by 11 | Viewed by 1516

Abstract

A small amount of Co was added to the Fe₈₈Ce₇B₅ glass forming alloy for the possibility of improving its glass formability and magnetocaloric effect. The Curie temperature of the amorphous Fe_88-xCe₇B₅Co [...] Read more.

A small amount of Co was added to the Fe₈₈Ce₇B₅ glass forming alloy for the possibility of improving its glass formability and magnetocaloric effect. The Curie temperature of the amorphous Fe_88-xCe₇B₅Co_x (x = 0, 1, 2, 3) ribbons increases linearly with the Co content, while the maximum magnetic entropy change (−ΔS_m^peak) increases to 3.89 J/(kg × K) under 5 T at x = 1 and subsequently decreases with further Co addition. The mechanism for the influence of Co addition on magnetic properties and the magnetocaloric effect of the amorphous alloys was investigated. Furthermore, a flattened −ΔS_m profile was designed in the amorphous laminate composed of the amorphous Fe_88-xCe₇B₅Co_x (x = 0, 1, 2) ribbons. The high average −ΔS_m from ~287 K to ~320 K indicates the potential application perspective of the amorphous hybrid as a magnetic refrigerant of a domestic refrigerator. Full article

(This article belongs to the Special Issue Forming Ability and Properties of Bulk Metallic Glasses)

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11 pages, 3527 KiB

Open AccessArticle

Enhanced Plasticity and Corrosion Resistance in Mg-Zn-Ca-Cu Amorphous Alloy Composite via Plasma Electrolytic Oxidation Treatment

by Qingling Zeng, Shuangshuang Chen, Peidi Song, Haodi Li and Xierong Zeng

Metals 2022, 12(2), 300; https://doi.org/10.3390/met12020300 - 9 Feb 2022

Cited by 5 | Viewed by 1332

Abstract

In this study, a dendrite-reinforced Mg-based amorphous alloy composite was prepared through an in situ precipitation strategy. After plasma electrolytic oxidation (PEO) treatment, the Mg_85.1Zn_12.7Ca₂Cu_0.2 amorphous alloy composite exhibited enhanced plasticity and corrosion resistance in a [...] Read more.

In this study, a dendrite-reinforced Mg-based amorphous alloy composite was prepared through an in situ precipitation strategy. After plasma electrolytic oxidation (PEO) treatment, the Mg_85.1Zn_12.7Ca₂Cu_0.2 amorphous alloy composite exhibited enhanced plasticity and corrosion resistance in a simulated body fluid solution (SBF). The PEO-treated composite showed a significant plastic strain of 10.5 ± 1.1%, as well as outstanding strain-hardening behavior. The enhancement of plasticity may be attributed to the in-situ formed coating, which can not only serve as a propagation barrier for shear bands but can also introduce nucleation sites in the bands as a result of stress mismatch and compositional heterogeneity. The corrosion density in the SBF decreased by three orders compared with the composite substrate. The spontaneous formation of apatite on the porous layer demonstrated that the prepared PEO coating has high bioactivity. The current work may provide a fundamental basis for developing biomedical Mg-based alloys with excellent comprehensive mechanical properties and corrosion resistance. Full article

(This article belongs to the Special Issue Forming Ability and Properties of Bulk Metallic Glasses)

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12 pages, 2340 KiB

Open AccessFeature PaperArticle

Observation of a Broadened Magnetocaloric Effect in Partially Crystallized Gd₆₀Co₄₀ Amorphous Alloy

by Ping Han, Ziyang Zhang, Jia Tan, Xue Zhang, Yafang Xu, Huiyan Zhang and Weihuo Li

Metals 2021, 11(11), 1741; https://doi.org/10.3390/met11111741 - 30 Oct 2021

Cited by 2 | Viewed by 1454

Abstract

To investigate the effect of crystallization treatment on the structure and magnetocaloric effect of Gd₆₀Co₄₀ amorphous alloy, the melt-spun ribbons were annealed at 513 K isothermally for 20, 40 and 60 min. The results indicate that, with increasing annealing time, [...] Read more.

To investigate the effect of crystallization treatment on the structure and magnetocaloric effect of Gd₆₀Co₄₀ amorphous alloy, the melt-spun ribbons were annealed at 513 K isothermally for 20, 40 and 60 min. The results indicate that, with increasing annealing time, the Gd₄Co₃ (space group P6₃/m) and Gd₁₂Co₇ (space group P2₁/c) phases precipitated from the amorphous precursor in sequence. In particular, in the samples annealed for 40 and 60 min, three successive magnetic transitions corresponding to the phases of Gd₄Co₃, Gd₁₂Co₇ and remaining amorphous matrix were detected, which induced an overlapped broadened profile of magnetic entropy change (|ΔS_M|) versus temperature. Under magnetic field changing from 0 to 5 T, |ΔS_M| values of 6.65 ± 0.1 kg⁻¹·K⁻¹ and 6.44 ± 0.1 J kg⁻¹·K⁻¹ in the temperature spans of 180–196 K and 177–196 K were obtained in ribbons annealed for 40 and 60 min, respectively. Compared with the fully amorphous alloy, the enhanced relative cooling power and flattened magnetocaloric effect of partially crystallized composites making them more suitable for the Ericsson thermodynamic cycle. Full article

(This article belongs to the Special Issue Forming Ability and Properties of Bulk Metallic Glasses)

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9 pages, 3883 KiB

Open AccessArticle

Formability and Magnetic Properties of the Binary Nd-Co Amorphous Alloys

by Qiang Wang, Ding Ding and Lei Xia

Metals 2021, 11(11), 1730; https://doi.org/10.3390/met11111730 - 29 Oct 2021

Cited by 7 | Viewed by 1192

Abstract

In this paper, binary Nd-Co alloys with compositional range from Nd_72.5Co_27.5 to Nd₅₀Co₅₀ were successfully vitrified into glassy state by a melt-spinning method. The glass formability of the metallic glasses (MGs) was studied and the best glass [...] Read more.

In this paper, binary Nd-Co alloys with compositional range from Nd_72.5Co_27.5 to Nd₅₀Co₅₀ were successfully vitrified into glassy state by a melt-spinning method. The glass formability of the metallic glasses (MGs) was studied and the best glass former in the binary Nd-Co alloys was obtained. Magnetic properties of the MGs were measured. The compositional dependence of Curie temperature of the MGs was observed. The mechanism for the spin-glass-like behaviors and high coercivity at low temperature, and their influence on the magnetic entropy change of the MGs, were investigated. Full article

(This article belongs to the Special Issue Forming Ability and Properties of Bulk Metallic Glasses)

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15 pages, 6642 KiB

Open AccessArticle

Effect of Strain Rate and Extrinsic SIZE Effect on Micro-Mechanical Properties of Zr-Based Bulk Metallic Glass

by Thamer Tabbakh, Abdulaziz Kurdi and Animesh Kumar Basak

Metals 2021, 11(10), 1611; https://doi.org/10.3390/met11101611 - 11 Oct 2021

Cited by 4 | Viewed by 1499

Abstract

In this study, the mechanical properties and deformation features of Zr-based bulk metallic glass (BMG) are investigated at micro-scale via in situ micro-pillar compression. Furthermore, the effects of the strain rate and micro-pillar diameter on respective stress–strain curves are investigated. Together with the [...] Read more.

In this study, the mechanical properties and deformation features of Zr-based bulk metallic glass (BMG) are investigated at micro-scale via in situ micro-pillar compression. Furthermore, the effects of the strain rate and micro-pillar diameter on respective stress–strain curves are investigated. Together with the mechanical properties, such unique in situ micro-pillar compression techniques provide physical status to the micro-pillars, referring to the instances of stress–strain curves. It is noted that the effect of the strain rate on the stress–strain behaviour of the BMG diminishes with increasing micro-pillar diameter. In contrast, yield and ultimate compressive strength increase with increasing micro-pillar diameter, up to 4 µm. The deformation details after compression, as a result of conformed mechanical loading, are analysed by SEM and TEM. As evident from electron microscopy investigation, the plastic deformation is evidenced by the presence of multiple slip/shear bands, acting as load accommodation mechanisms in the course of mechanical loading together and resemble local plastic flow (ductile in nature) between two shear plans. Full article

(This article belongs to the Special Issue Forming Ability and Properties of Bulk Metallic Glasses)

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10 pages, 3059 KiB

Open AccessArticle

Effect of Mn Substitution Fe on the Formability and Magnetic Properties of Amorphous Fe₈₈Zr₈B₄ Alloy

by Xin Wang, Qiang Wang, Benzhen Tang, Ding Ding, Li Cui and Lei Xia

Metals 2021, 11(10), 1577; https://doi.org/10.3390/met11101577 - 3 Oct 2021

Cited by 6 | Viewed by 1374

Abstract

Elemental substitution is commonly used to improve the formability of metallic glasses and the properties of amorphous alloys over a wide compositional range. Therefore, it is essential to investigate the influence of element content change on the formability as well as magnetic and [...] Read more.

Elemental substitution is commonly used to improve the formability of metallic glasses and the properties of amorphous alloys over a wide compositional range. Therefore, it is essential to investigate the influence of element content change on the formability as well as magnetic and other properties. The purpose is to achieve tailorable properties in these alloys with enhanced glass forming ability. In this work, the glass-forming ability (GFA) and magnetic properties of the minor Mn-substituted Fe₈₈Zr₈B₄ amorphous alloy were investigated. The addition of Mn improving the amorphous forming ability of the alloy. With the addition of Mn, the magnetic transition temperature, saturation magnetization and the magnetic entropy changes (−ΔS_m) peaks decreased simultaneously, which is possibly caused by the antiferromagnetic coupling between Fe and Mn atoms. The dependence of −ΔS_m^peak on T_c displays a positive correlation compared to the −ΔS_m^peak- T_c^−2/3 relationship proposed by Belo et al. Full article

(This article belongs to the Special Issue Forming Ability and Properties of Bulk Metallic Glasses)

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14 pages, 2556 KiB

Open AccessArticle

Influence of Cold Rolling Process and Chemical Composition on the Mechanical Properties and Corrosion Behavior of Zr-Based Metallic Glasses

by Ali Akbarpour, Daria A. Milkova, Erzhena N. Zanaeva, Mark S. Parkhomenko, Vladimir V. Cheverikin, Alexander Lubenchenko and Andrey I. Bazlov

Metals 2021, 11(10), 1514; https://doi.org/10.3390/met11101514 - 24 Sep 2021

Cited by 4 | Viewed by 1952

Abstract

Cold rolling (CR) with thickness reduction of 10%, 30%, and 50% was applied to Zr₅₀Cu₄₄Al₆ and Zr_49.5Cu₄₄Al₆Nb_0.5 metallic glassy ribbon samples. The XRD patterns showed the amorphousness of all samples after [...] Read more.

Cold rolling (CR) with thickness reduction of 10%, 30%, and 50% was applied to Zr₅₀Cu₄₄Al₆ and Zr_49.5Cu₄₄Al₆Nb_0.5 metallic glassy ribbon samples. The XRD patterns showed the amorphousness of all samples after casting and CR processes. The SEM images indicated the formation of multiple shear bands (SBs) owing to plastic deformation during CR. However, the addition of 0.5 at% Nb to the alloy changed the SBs’ density and spacing characteristics. The characterization of free volume changes caused by CR was carried out by measuring the density of Archimedes. The micro-hardness of samples was studied by investigating SBs and free volume during plastic deformation. Alloy softening occurred due to the formation of free volume during CR. X-ray photoelectron spectroscopy (XPS) confirmed the presence of oxides ZrO₂, CuO_x, and AlO_x on the surface of the ribbons. The anodic polarization curves of the cast and R50 samples in solutions of NaCl and Na₂SO₄ (0.5 M) were obtained using potentiodynamic polarization measurements. Compared to CR ribbons, melt-spun ribbons after casting showed better corrosion resistance with lower anodic current densities in Na₂SO₄ solution. Full article

(This article belongs to the Special Issue Forming Ability and Properties of Bulk Metallic Glasses)

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12 pages, 18351 KiB

Open AccessArticle

Investigation of Thermophysical Properties of Zr-Based Metallic Glass-Polymer Composite

by Adit Sharma, Mikhail Zadorozhnyy, Andrey Stepashkin, Aksar Kvaratskheliya, Artem Korol, Dmitri Moskovskikh, Sergey Kaloshkin and Vladislav Zadorozhnyy

Metals 2021, 11(9), 1412; https://doi.org/10.3390/met11091412 - 7 Sep 2021

Cited by 5 | Viewed by 1931

Abstract

Composites based on Zr₆₅Cu_17.5Ni₁₀Al_7.5 metallic glass (MG) and polytetrafluoroethylene (PTFE) were prepared by ball milling. Different composites (30/70, 50/50 and 70/30) were produced. Samples for dynamic mechanical analysis and laser flash analysis were fabricated in the [...] Read more.

Composites based on Zr₆₅Cu_17.5Ni₁₀Al_7.5 metallic glass (MG) and polytetrafluoroethylene (PTFE) were prepared by ball milling. Different composites (30/70, 50/50 and 70/30) were produced. Samples for dynamic mechanical analysis and laser flash analysis were fabricated in the supercooled region of the metallic glass and viscous region of the polymer. Spark plasma sintering (SPS) was performed at the supercooled region for the metallic glass powder. Characteristics such as thermal, mechanical, and structural properties were studied. A formation of the Zr₂Cu and Zr₂Ni intermetallic was found in the metallic glass after SPS. A formation of the nanocrystalline Zr₂Cu was found in composite samples. Dynamical mechanical analysis (DMA) was used to study the mechanical behavior of the material. It was concluded that the 70/30-MG/PTFE composite sample had better thermal conductivity than the other composite samples. The thermal conductivity of the metallic glass was the highest among the samples and it increased with the MG content in composites. Full article

(This article belongs to the Special Issue Forming Ability and Properties of Bulk Metallic Glasses)

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