Next Article in Journal
FEM Simulation on First-Step Drawing Process of Platinum-Clad Nickel Bars
Previous Article in Journal
Enhancing the Tribological Performance of Tool Steels for Wood-Processing Applications: A Comprehensive Review
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Metals
Volume 13
Issue 8
10.3390/met13081461
metals-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Study on the Microstructure and High-Temperature Oxidation Performance of β-NiAl/γ′-Ni3Al Intermetallic Compounds Fabricated by Laser Metal Deposition

by
Xun He
*,
Xiao Peng
and
Juan Fang
School of Material Science and Engineering, Nanchang Hangkong University, 696 Fenghenan Avenue, Nanchang 330063, China
*
Author to whom correspondence should be addressed.
Metals 2023, 13(8), 1461; https://doi.org/10.3390/met13081461
Submission received: 19 June 2023 / Revised: 7 August 2023 / Accepted: 11 August 2023 / Published: 14 August 2023
Browse Figures
Versions Notes

Abstract

:
Four Ni-Al intermetallic compounds with the Al concentrations in range of 28 to 35 (in atomic percentage) have been fabricated by laser metal deposition (LMD) through mixing appropriate contents of pure Ni powder with pre-alloyed high-Al nickel aluminide powder. Ni-35Al and Ni-32Al are both composed of more than 45 vol.% β-NiAl matrix phase dispersing γ′-Ni3Al, while Ni-30Al and Ni-28Al consisted of worm-like, needle-like γ′-Ni3Al mainly and less than 37 vol.% β-NiAl. After 20 h oxidation in air at 1000 °C, the results of thermobalance, X-ray diffraction and scanning electron microcopy, indicated that Ni-35Al and Ni-32Al are more oxidation-resistant than the Ni-30Al and Ni-28Al. Because the first two can thermally grow an external Al2O3 scale but the second two form a duplex oxide scale consisting of outer NiAl2O4 layer and inner Al2O3 layer.

1. Introduction

The β-NiAl intermetallic compound is considered as an attractive material for high-temperature structural applications, such as turbine elements or other heat- and oxidation-resistant components, due to its several merits, including its high melting point, good thermal conductivity, and relatively low density [1,2,3]. Unfortunately, engineering applications of the intermetallic alloy have been limited, but it possesses low ductility and toughness. An attractive approach to minimizing the drawbacks is toughening with a ductile phase γ′-Ni3Al [4,5,6,7]. And both β-NiAl and γ′-Ni3Al are oxidation-resistant intermetallic compounds which could form an external protective alumina scale [8,9,10,11]. Therefore, it is possible that β/γ′ two-phase alloys could obtain better high-temperature mechanical properties without compromising their oxidation performance.
Many researchers prepared β/γ′ two-phase alloys using conventional methods, such as vacuum arc melting [5,9] and directional solidification [4,6,7]. An advanced method of laser metal deposition (LMD) has recently gained much attention, due to its advantage in manufacturing components and parts with complex geometries with less material waste, quicker turnaround times, and lower costs [12]. LMD has been used for the manufacturing of some high-temperature alloys [13,14,15], such as Ni718, etc. As a highly promising high-temperature alloy, Ni-Al intermetallic compounds are of great interest as well. Many researchers [16,17,18,19,20,21,22,23,24] have investigated the capabilities of the AM method to manufacture Ni-Al alloys with different chemical compositions. Kotoban [16,17,18] investigated the processing of pre-alloyed Ni85Al15 powder by LMD for single and multi-layer build-ups. And Yu [19,20,21] synthesized nickel aluminide (NiAl) intermetallic compound coatings in situ from pre-placed mixed powders of Ni and Al by means of laser cladding. However, LMD manufacturing of defect (i.e., pore, crack, etc.)-free Ni-Al intermetallic compounds with the desired comprehensive mechanical properties is currently a difficult challenge [22,23,24]. Crack defects easily appear due to the combined effects of the brittleness of alloys and the high thermal stresses generated during AM processing. Therefore, appropriate parameters for manufacturing Ni-Al intermetallic compounds still need to be studied, and reports regarding the oxidation performance of LMD Ni-Al alloys are also rarely seen.
In this paper, β/γ′ two-phase alloys with different compositions were fabricated by the LMD method with Ni-Al pre-alloyed and elemental Ni mixed powders, and the microstructure and solidification mode were analyzed. Studies on the oxidation of β/γ′ alloys have characterized the scale-growth mechanisms and kinetics, scale microstructures, and morphologies at 1000 °C in air for 20 h, and these have been compared with the oxidation resistance of Ni-Al alloys fabricated by other methods. It has been proven that β/γ′ Ni-Al alloys with great oxidation resistance could be manufactured using the LMD method, and this work lays a foundation for improving the oxidation resistance of Ni-Al alloys processed by LMD. In addition, it is known that the properties of real components with larger dimensions may differ from the findings obtained with laboratory samples. Therefore, further studies regarding the additive manufacturing of large-scale β/γ′ alloys are needed in the future.

2. Materials and Methods

2.1. Materials

The β/γ′ dual-phase Ni-Al intermetallic alloy was prepared by LMD via mixing the commercial Ni-67Al alloy particles (consisting of Ni2Al3 and NiAl3 dual phase on a basis of XRD characterization) with a certain amount of pure Ni (purity > 99.9%) powder, following the Ni-Al binary phase diagram, as will be addressed later. Figure 1a shows the morphology of the as-received Ni-67Al powder particles. They had irregular granular shapes. Their sizes were statistically measured in the range of 10 to 80 μm, with a mean particle size of 19.6 μm. The pure Ni powder was prepared by N2-gas-atomized method and displayed a spherical shape, as presented in Figure 1b. They varied in size from 10 to 45 μm and had an average diameter of 19.2 μm. The two powder particles for LMD were mixed in advance using jar milling, then dried out by heating up to over 100 °C for 4 h before being loading into the powder feeder. The LMD process was carried out on a polished pure nickel plate (Ni 200) with dimensions of Φ 22 mm × 10 mm.

2.2. Method

Figure 2a illustrates the process of manufacturing the Ni-Al intermetallic alloy by LMD in a chamber (8060 SYSTEM laser additive manufacturing equipment, RAYCHAM Inc., Nanjing, China), as presented in Figure 2b. The LMD chamber is composed of a Laserline LDF 3000-60 semiconductor laser generator, a two-nozzle coaxial powder feed system, a multi-axis motion control system, and a temperature control system. The experimental parameters are listed in Table 1. During the LMD process, the Ni-200 substrate was preheated to a temperature of ~500 °C with an induction heating coil so as to prevent the intermetallic alloy cracking triggered by the unacceptable thermal stresses due to the large temperature difference between the hot printing alloy and the cool substrate. The results of Liu [23] and Müller [24] indicated that cracking was mainly caused by the high thermal stresses, and the aluminum-rich composition exhibited a high solidification cracking susceptibility and porosity formation. An appropriate preheating temperature on the substrate and a low scanning speed would alleviate these adverse effects.
According to the Ni-Al phase diagram (Figure 3), a β/γ′ dual-phase Ni-Al intermetallic alloy can prepared by LMD by adjusting the Ni content from 58 at.% to 74 at.% through mixing appropriate contents of the Ni powder with the Ni-67Al powder. In this study, four Ni-Al intermetallic alloys with Al contents of 35 at.%, 32 at.%, 30 at.%, and 28 at.%, respectively, were designed for additively manufacturing and marked with Ni-35Al, Ni-32Al, Ni-30Al, and Ni-28Al, respectively, as shown in Figure 3. These four alloys share two different types of solidification processes, described below.
During the solidification of Ni-35Al and Ni-32Al, alloys experienced a solid–liquid (L + β) two-phase region first and a solid β phase region afterward, ending at the solid (β + γ′) two-phase region [5,6]. When the temperature decreased to the point T4, the β phase firstly precipitated out from the molten pool. When the temperature further decreased to the point T5, all liquid transformed into the β-NiAl, and the isomorphous reaction was over. And along with the further decrease in temperature to the point T6, the exsolution reaction started, and the metastable Ni-rich β-NiAl transformed into Ni3Al and stable β-NiAl. Therefore, the fine γ′-Ni3Al precipitations dispersed inside the β-NiAl matrix or along the grain boundaries.
During the solidification of Ni-30Al and Ni-28Al, the alloys experienced a solid-liquid (L + β) two-phase region, and then ended at the solid two-phase region (β + γ′) directly [4,9]. When the temperature decreased to the point T1, the β phase precipitated out from the molten pool. When the temperature was reduced to the peritectic temperature point T2, the γ′-Ni3Al was obtained via the peritectic reaction of L + β-NiAl → γ′-Ni3Al. As the primary β phase was completely surrounded by the γ′ phase, the peritectic reaction was inhibited, because the high cooling rate would stop the atomic movement between the solid and liquid phases. And the remaining liquid would transform into the γ′-Ni3Al directly at the point T3 (slightly lower than the peritectic temperature). Therefore, this part of the γ′ phase was coarse and surrounded the primary β phase, forming a net shape. And because the peritectic reaction did not carry out completely, the primary β phase is was Ni-rich and metastable. When the temperature further decreased, the metastable β-NiAl transformed into γ′-Ni3Al and stable β-NiAl. Therefore, it could be observed in low-Al Ni-Al alloys that the fine β and γ′ phase precipitations were distributed inside the coarse γ′ phase.
The as-printed alloy had dimensions of 10 mm × 10 mm × 3 mm. It was cut into small samples of 8 mm × 8 mm × 1.5 mm. After being ground with SiC papers to a 600-grit size, washed with water, and ultrasonically cleaned with acetone, the samples were used for oxidation. Isothermal oxidation was performed at 1000 °C in air using a SETARAM Setsys Evolution thermogravimetric analyzer (TGA, KEP technologies, Lyon, France). The phase compositions before and after oxidation were identified by X-ray diffraction (XRD, Bruker Corporation, Billerica, Germany). The morphologies and microstructures of the LMD Ni-Al intermetallic alloys before and after oxidation were investigated using light optical microscopy (OM, Olympus Corporation, Tokyo, Japan) and scanning electron microscopy (SEM, FEI Inc, Hillsboro, USA) with energy-dispersive spectrum (EDS) analysis. Some samples for OM observation were etched in Marble’s reagent (10 g CuSO4, 50 mL HCl, and 50 mL H2O) after polishing.

3. Results and Discussion

3.1. Phase and Microstructure Analysis

The phase compositions of the four as-printed Ni-Al intergalactic alloys were characterized by XRD. It was found that the Ni-35Al and Ni-32Al had similar phase compositions, while the phase compositions of Ni-30Al and Ni-28Al were analogous. Accordingly, the two typically-different XRD patterns are presented in Figure 4a–d, respectively. Ni-35Al and Ni-32Al were mainly composed of γ′-Ni3Al and β-NiAl phases. The other alloys, Ni-30Al and Ni-28Al, were also γ′/β dual-phase alloys, but the intensity ratio of the strongest NiAl (110) peak to the strongest Ni3Al peak became smaller, implying that the two lower-Al-containing alloys had decreased in the volume fraction of the β phase, but increased in the γ′ phase. In addition, some M-NiAl were obtained in Ni-35Al, and Smialek [25] indicated that the martensitic reaction occurred only for NiAl with greater than 63 at.% Ni and only when quenched from 1000 °C or above. As LDM is a process of rapid heating and cooling, M-NiAl could appear in the alloys according to above conditions.
In good agreement with the XRD characterization, the two typical β/γ′ dual-phase microstructures of the four LMD Ni-Al intermetallic alloys were also observed by OM. Taking the microstructures of the Ni-32Al (Figure 5d–f) and Ni-28Al (Figure 5j–l) as examples, the Ni-Al intermetallic alloys Ni-35Al and Ni-32Al were generally dispersed with fine β (dark phase) and γ′ (lighter phase) (Figure 5d,e). Figure 5f shows a magnified view of the framed area in Figure 5d, that is, the boundary area between two laser molten pools. This is evidently indicative of a higher β phase area fraction on the boundary area than on most other areas. In contrast, the lower-Al Ni-Al intermetallic alloys Ni-30Al and Ni-28Al formed fewer β and coarser γ′ phases (Figure 5j,k); on the boundary area between two laser molten pools (see the framed area in Figure 5j), it also appeared that the β phase area fraction was obviously increased (Figure 5l). Based on the OM observations, the Ni-35Al was calculated to be composed of 48.1 vol.% β and 51.9% γ′, while there was 45.9 vol.% β and 54.1% γ′ in the Ni-32Al. However, the two phases of the two alloys displayed fine microstructures. Strikingly, when the Al concentration decreased to 30 at.%, the β volume fraction sharply reduced to 36.2%, while the γ′ volume fraction was enlarged to 64.3 vol.%. The Ni-28Al further evolved into a (25.7 vol.% β + 74.3% γ′) dual-phase alloy.
The aforementioned differences in phase microstructures are caused by the Al concentration difference on the one hand; on the other hand, the differences result from the rapid non-equilibrium solidification process of the alloy during LMD. As shown in Figure 3 and mentioned in Section 2.2, the solidification of Ni-35Al and Ni-32Al alloys experienced a solid–liquid (L + β) two-phase region first and a solid β phase region afterward. All of the γ′-Ni3Al phase precipitated out from the metastable Ni-rich β-NiAl through a solid-state phase transition. But the rapid solidification process of LMD inhibited this precipitation reaction, resulting in a certain amount of the β-NiAl phase remaining at room temperature. As a comparison, the solidification of the Ni-30Al and Ni-28Al alloys experienced a solid–liquid (L + β) two-phase region firstly, and then ended at the solid two-phase region (β + γ′) directly. The γ′-Ni3Al phase would be generated via the peritectic reaction of L + β-NiAl → γ′-Ni3Al and the solid-state phase transition of β-NiAl → β-NiAl + γ′-Ni3Al. The peritectic process is a reaction between the solid β-NiAl phase and liquid phase at a higher temperature than the solid-state phase transition. The former reaction was carried out more thoroughly than the latter and precipitated more of the γ′-Ni3Al phase. This is the reason that the β volume fraction was sharply reduced when the Al concentration decreased to 30 at.%.

3.2. Oxidation Kinetics

Figure 6a shows the oxidation curves of the β/γ′ Ni-Al intermetallic alloys during 20 h of isothermal oxidation at 1000 °C in air. Ni-35Al and Ni-32Al displayed two oxidation curves with similar features of time-dependent variation. Interestingly, this phenomenon was also visible from the oxidation curves of the other lower Al alloys Ni-30Al and Ni-28Al. From the corresponding parabolic plots presented in Figure 6b, no significant difference was found in the parabolic rate constant kp of Ni-35Al and Ni-32Al, which was 2.1 × 10−13 g2/cm4∙s and 3.9 × 10−13 mg2/cm4∙s, respectively. Ni-30Al (2.0 × 10−12 g2/cm4∙s) and Ni-28Al (1.6 × 10−12 g2/cm4∙s) also displayed similar kp values. However, their kp values were dramatically higher than those of Ni-35Al and Ni-32Al.
The phase compositions of the oxide scales of four Ni-Al alloys after 20 h of oxidation were characterized by XRD. It was found that the Ni-35Al and Ni-32Al had similar phase compositions, while the phase compositions of Ni-30Al and Ni-28Al were analogous. Therefore, the two typically-different XRD patterns are displayed in Figure 7a,b, respectively. The oxide scales of Ni-35Al and Ni-32Al mainly consisted of Al2O3, while those of Ni-30Al and Ni-28Al were composed of not only Al2O3, but also NiO and spinel NiAl2O4.
To better understand the relationship between the microstructures of the LMD Ni-Al alloys and their oxidation performances, the characteristics of the phase microstructure, types of thermally-grown oxides (TGOs), and kp values of the four LMD Ni-Al alloys are summarized in Table 2.

3.3. Oxide Scale Composition and Microstructure

The morphologies of the oxide scales formed on the four LMD alloys were investigated by SEM/EDS in combination with XRD characterization. It was found that Ni-35Al and Ni32Al generally developed an Al2O3 scale, while Al2O3 and NiAl2O4 occurred on the other two lower-Al alloys. To better clarify this, the surface and cross-sectional morphologies of the oxide scales on Ni-32Al and Ni-28Al are comparatively presented and detailed below.
Figure 8 shows the surface morphology of Ni-32Al and Ni-28Al after 20 h of oxidation in air at 1000 °C. The higher-Al β/γ′ intermetallic alloy (Figure 8a) grew fine-grained Al2O3 on most areas, as framed. The inset is a magnified image of the framed area, showing that the TGOs there appeared to be rod-like or granular crystals. The granular crystals were formed on the γ′-Ni3Al phase. This will be interpreted later. The rod-shaped alumina was credibly in θ form. The formation of meta-stable θ-Al2O3 on β-NiAl oxidized at 1000 °C and below has been extensively reported [26,27,28,29,30,31]. The thermally grown θ-Al2O3 crystals are normally whisker- or needle-shaped. They are coarsened and blunted into rod-like crystals as they converted to α-Al2O3 [32]. Moreover, there were two minor regions which grew Al2O3 with different features. One type appeared as protrusions, as indicated by “A” in Figure 8a, where Al2O3 grew faster and appeared to be more needle-like. The other appeared as some concave areas, as indicated by “B”, where Al2O3 grew more slowly and was composed of fine oxide crystals. The formation of the alumina scale with different crystal shapes was undoubtedly associated with the distribution of the alloy β and γ′ phases. β-NiAl preferentially grew θ-Al2O3. This oxide was later transformed into denser and more stable α-Al2O3, starting from the θ-Al2O3/alloy interface [28]. The growth of α-Al2O3 was one and two orders of magnitude lower than that of θ-Al2O3 [33]. When α-Al2O3 nucleated and developed most quickly somewhere at the interface, the overlying θ-Al2O3 subsequently grew at a much slower rate, leading to the occurrence of a concaved region on the surface [33]. Conversely, θ-Al2O3 grew more quickly on the regions with the slowest θ-to-α-phase transformation rate, forming needle-shaped θ-Al2O3. protrusions. The other granular oxide crystals were assumed to develop on the γ′-Ni3Al phase of the printed two-phase alloy. Peng and co-workers [34] found that significant grain refinement promoted the rapid formation of an α-Al2O3 layer below a thin and very fine-grained NiO. The γ′-Ni3Al phase could be fine-grained as a result of the rapid solidification of the laser molten pool during the cooling process. The α-Al2O3 layer formation blocked the outer NiO growth. This oxide was reduced to Ni when it was swept over the outward-growing part of the α-Al2O3 later. The reduced Ni diffused toward the oxide/alloy interface [33]. Therefore, the granular oxide crystals were assumed to be α-Al2O3, because Ni-containing oxides were not observed by EDS or XRD. In contrast, there were two oxide features on the lower-Al β/γ′ intermetallic alloy (Figure 8b). The inset of a magnified image of the framed area indicated that two oxides were different in grain size. They were, however, composed of Ni, Al, and O on the basis of EDS analysis, and were accordingly presumed to be NiAl2O4 according to XRD characterization. The spinel oxide displayed two different morphologies because of the different growth rates of underlying alumina on the β and γ′ of the lower-Al alloy. Fine-grained NiAl2O4 developed on the area where the spinel oxide could be quickly undermined by the underlying formed alumina layer. The reverse result occurred on the other, with a slower alumina growth rate.
Figure 9a shows the cross-sectional morphology of Ni-32Al after 20 h of oxidation in air at 1000 °C. The β/γ′ intermetallic alloy formed a thin oxide scale. It was pure Al2O3, as evidently revealed by the inset. Differently from the inset of Figure 9b for Ni-28Al oxidized under the same condition, the lower-Al intermetallic alloy formed a double-layered oxide scale consisting of an inner Al2O3 layer and an outer NiAl2O4 spinel layer including a few NiO particles. The conventional γ′-Ni3Al alloy thermally grew NiO, NiAl2O4, and Al2O3 [34,35,36]. However, only a few Ni grains occurred on the lower-Al LMD alloy, although it was dispersed with a high density of γ′-Ni3Al. The reason is also correlated with the fact that the rapid solidification process refined the LMD alloy grains, which promoted the alumina growth, as addressed above.

3.4. Oxide Scale Growth Mechanism

According to Figure 6, the four LMD Ni-Al alloys exhibited very similar oxidation curves approximately ahead of the first 4 h. This implies that the four alloys had similar oxidation processes. However, Ni-35Al and Ni-32Al formed an Al2O3 scale, while Ni-30Al and Ni-28Al formed a double-layered oxide scale consisting of outer NiAl2O4 and inner Al2O3. This suggests that Ni-30Al and Ni-28Al may also grow an external Al2O3 scale, but its steady-state growth cannot be maintained thereafter. This is the reason that, after 4 h, the two lower Al Ni-Al alloys displayed much faster rates. On this basis, it is proposed that there is a critical Al concentration ranging from 30 at.% to 32 at.% for the LMD β/γ′ dual-phase Ni-Al alloys to consistently grow an external alumina scale. The formation of the alumina scale occurs through two different routes. The β phase of the alloy preferentially grows θ-Al2O3. However, the θ-to-α alumina phase transformation rate is affected by the β phase size and distribution density. This leads to the surface θ-Al2O3 displaying a different growth rate and, consequently, a different crystal shape. In addition, the alloy γ′ phase, due to its LMD-induced fine-grained structure, quickly grows an α-Al2O3 layer below the preferentially formed NiO layer. The latter stopped growing accordingly and was converted into NiAl2O4 by its reaction with Al2O3. When the NiAl2O4 layer (including the NiO inclusions) was swept over by the outward-growing part of the α-Al2O3 layer, the spinel oxide was further converted to α-Al2O3. Finally, an external scale of alumina (i.e., (a θ-Al2O3 and α-Al2O3 mixture) was developed. The external alumina scale can sustainably grow if the Al content reaches the critical value mentioned above. This should be the case for the oxidation of Ni-32Al and Ni-35Al. On the contrary, NiAl2O4 and NiO grew above the formed alumina scale. This may occur with the Ni-30Al and Ni-28 Al. The two lower-Al LMD alloys, in comparison to Ni-32Al and Ni-35Al, were larger in both the phase size (Figure 5) and volume fraction (Table 2) of γ′. The low Al content in the phase may not maintain the steady-state growth of the formed alumina scale.

4. Conclusions

β-NiAl/γ′-Ni3Al two-phase Ni-Al intermetallic alloys with Al concentrations varying from 35 at.% to 28 at.% were additively manufactured via LMD by deliberately mixing the appropriate amounts of pure Ni powder particles with Ni-67Al powder particles. The solidification of Ni-35Al and Ni-32Al alloys involves a solid–liquid (L + β) two-phase region firstly and a solid β phase region afterward, ending at the solid (β + γ′) two-phase region. This is different from Ni-30Al and Ni-28Al, which experience a solid–liquid (L + β) two-phase region and then end at the solid two-phase region (β + γ′) directly. When the Al concentration is decreased to 30 at.%, the β volume fraction is sharply reduced. During 20 h of oxidation in air at 1000 °C, Ni-35Al and Ni-32Al formed an external Al2O3 scale, while Ni-30Al and Ni-28Al formed a double-layered oxide scale consisting of outer NiAl2O4 and inner Al2O3. This led to the first two LMD alloys having oxidation rates dramatically lower than the second two. The result suggests that the LMD β/γ′ dual-phase Ni-Al alloys have the ability to consistently grow alumina scales. The Al concentration should approach 32 at.%.

Author Contributions

Conceptualization, X.P., X.H. and J.F.; methodology, X.P.; software, X.H. and J.F.; validation, X.P., X.H. and J.F.; formal analysis, X.P.; investigation, X.H. and J.F.; resources, X.H. and J.F.; data curation, X.H. and J.F.; writing—original draft preparation, X.P. and X.H.; writing—review and editing, X.P.; visualization, X.H. and J.F.; supervision, X.P.; project administration, X.P.; funding acquisition, X.P. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Jiangxi Provincial Key Research and Development Program of China (project Grant No. 20192ACB80001).

Data Availability Statement

The raw/processed data required to reproduce these findings cannot be shared at this time due to technical or time limitations. They will be shared upon request.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Gong, N.; Meng, T.L.; Teo, S.L.; Cao, J.; Lee, C.J.; Tan, C.K.I.; Tan, D.C.; Suwardi, A.; Lin, M.; Misra, R.D.K.; et al. High-temperature oxidation and hot corrosion of Ni-based single crystal superalloy in the incubation stage. Corros. Sci. 2023, 214, 111026. [Google Scholar] [CrossRef]
  2. Zagula-Yavorska, M.; Romanowska, J. The effect of precious metals in the NiAl coating on the oxidation resistance of the Inconel 713 superalloy. J. Min. Metall. B Metall. 2022, 58, 299–310. [Google Scholar] [CrossRef]
  3. Wu, Y.T.; Li, C.; Li, Y.F.; Wu, J.; Xia, X.C.; Liu, Y.C. Effects of heat treatment on the microstructure and mechanical properties of Ni3Al-based superalloys: A review. Int. J. Miner. Metall. Mater. 2021, 28, 553–566. [Google Scholar] [CrossRef]
  4. He, J.; Peng, H.; Gong, S.; Guo, H. Synergistic effect of reactive element Co-doping in two-phase (γ′ + β) Ni-Al alloys. Corros. Sci. 2017, 120, 130–138. [Google Scholar] [CrossRef]
  5. Lee, J.H.; Lee, S.Y.; Lee, Z.H.; Kim, H.M. Ni3Al precipitation behavior in the two-phase (NiAl + Ni3Al) alloy. High Temp. Mater. Process. 1999, 18, 125–130. [Google Scholar] [CrossRef]
  6. Kim, S.H.; Oh, M.H.; Wee, D.M. Microstructure control of DS NiAl/Ni3Al alloy by fabrication of columnar-grained NiAl martensite. Mater. Sci. Forum 2003, 426–432, 1813–1818. [Google Scholar] [CrossRef]
  7. Povarova, K.B.; Drozdov, A.A.; Bazyleva, O.A.; Morozov, A.E.; Antonova, A.V.; Bondarenko, Y.A.; Bulakhtina, M.A.; Ashmarin, A.A.; Arginbaeva, E.G.; Alad’Ev, N.A. Structural heat-resistant β-NiAl + γ′-Ni3Al alloys of the Ni–Al–Co system: I. solidification and structure. Russ. Metall. 2017, 9, 696–705. [Google Scholar] [CrossRef]
  8. Yang, Y.F.; Ren, S.X.; Deng, C.M.; Ren, P.; Zhang, P.M.; Peng, R.L.; Bao, Z.B.; Li, W. Synergistic effect of Pt and Hf on the early-stage oxidation behaviour of NiAl coating at 1000 °C. Corros. Commun. 2022, 5, 49–61. [Google Scholar] [CrossRef]
  9. He, J.; Zhang, Z.; Peng, H.; Gong, S.; Guo, H. The role of Dy and Hf doping on oxidation behavior of two-phase (γ′ + β) Ni–Al Alloys. Corros. Sci. 2015, 98, 699–707. [Google Scholar] [CrossRef]
  10. Yu, M.; Sun, Q.; Wang, Q.; Li, X.; Zhou, D.; Pu, J.; Chen, B.; Li, C. Effect of Pt-doping on the oxidation behaviors of the γ′-Ni3Al and β-NiAl phases in the NiSiAlY alloy. Corros. Sci. 2022, 200, 110224. [Google Scholar] [CrossRef]
  11. Zhou, B.; Zhou, Q.; He, J.; Wang, W.; Guo, H. A comprehensive study on the oxidation behavior and failure mechanism of (γ′ + β) two-phase Ni-34Al-0.1Dy coating treated by laser shock processing. J. Mater. Sci. Technol. 2023, 162, 131–144. [Google Scholar] [CrossRef]
  12. Askari, M.; Hutchins, D.A.; Thomas, P.J.; Astolfi, L.; Watson, R.L.; Abdi, M.; Ricci, M.; Laureti, S.; Nie, L.; Freear, S.; et al. Additive manufacturing of metamaterials: A review. Addit. Manuf. 2020, 36, 101562. [Google Scholar] [CrossRef]
  13. Farias, F.W.C.; Duarte, V.R.; Felice, I.O.; da Cruz Payao Filho, J.; Schell, N.; Maawad, E.; Avila, J.A.; Li, J.Y.; Zhang, Y.; Santos, T.G.; et al. In situ interlayer hot forging arc-based directed energy deposition of Inconel® 625: Process development and microstructure effects. Addit. Manuf. 2023, 66, 103476. [Google Scholar] [CrossRef]
  14. Prost, M.; Köster, A.; Missoum-Benziane, D.; Dépinoy, S.; Ferhat, L.; Rambaudon, M.; Maurel, V. Anisotropy in cyclic behavior and fatigue crack growth of IN718 processed by laser powder bed fusion. Addit. Manuf. 2023, 61, 103301. [Google Scholar] [CrossRef]
  15. Sanviemvongsak, T.; Monceau, D.; Desgranges, C.; Macquaire, B. Intergranular oxidation of Ni-base alloy 718 with a focus on additive manufacturing. Corros. Sci. 2020, 170, 108684. [Google Scholar] [CrossRef]
  16. Kotoban, D.; Nazarov, A.; Shishkovsky, I. Comparative study of selective laser melting and direct laser metal deposition of Ni3Al intermetallic alloy. Procedia IUTAM 2017, 23, 138–146. [Google Scholar] [CrossRef]
  17. Kotoban, D.; Aramov, A.; Tarasova, T. Possibility of multi-material laser cladding fabrication of nickel alloy and stainless steel. Phys. Procedia 2016, 83, 634–646. [Google Scholar] [CrossRef]
  18. Kotoban, D.; Grigoriev, S.; Shishkovsky, I. Study of 3D laser cadding for Ni85Al15 superalloy. Phys. Procedia 2014, 56, 262–268. [Google Scholar] [CrossRef] [Green Version]
  19. Youjun, Y.; Jiansong, Z.; Lianbin, Y.; Jianmin, C.; Huidi, Z.; Chun, G.; Lingqian, W. Phase and microstructure properties of laser cladding NiAl intermetallic compound coating at elevated temperature. Rare Met. Mater. Eng. 2012, 41 (Suppl. 1), 116–119. [Google Scholar]
  20. Yu, Y.; Zhou, J.; Chen, J.; Zhou, H.; Guo, C.; Wang, L.; Yang, L. Preparation, microstructure and tribological behavior of laser cladding NiAl intermetallic compound coatings. Wear 2012, 274–275, 298–305. [Google Scholar] [CrossRef]
  21. Yu, Y.; Zhou, J.; Ren, S.; Wang, L.; Xin, B.; Cao, S. Tribological properties of laser cladding NiAl intermetallic compound coatings at elevated temperatures. Tribol. Int. 2016, 104, 321–327. [Google Scholar] [CrossRef]
  22. Abboud, J.H.; Rawlings, R.D.; West, D.R.F. Functionally graded nickel-aluminide and iron-aluminide coatings produced via laser cladding. J. Mater. Res. 1995, 30, 5931–5938. [Google Scholar] [CrossRef]
  23. Liu, W.; Dupont, J.N. In-situ reactive processing of nickel aluminides by laser-engineered net shaping. Metall. Mater. Trans. A 2003, 34, 2633–2641. [Google Scholar] [CrossRef]
  24. Müller, M.; Heinen, B.; Riede, M.; López, E.; Brückner, F.; Leyens, C. Additive manufacturing of β-NiAl by means of laser metal deposition of pre-alloyed and elemental powders. Materials 2021, 14, 2246. [Google Scholar] [CrossRef]
  25. Smialek, J.L. Martensite in NiAl oxidation-resistant coatings. Metall. Mater. Trans. B 1971, 2, 913–915. [Google Scholar] [CrossRef]
  26. Zhou, B.; He, J.; Zhou, Q.; Guo, H. Effects of laser shock processing on θ-Al2O3 to α-Al2O3 transformation and oxide scale morphology evolution in (γ′ + β) two-phase Ni-34Al-0.1Dy alloys. J. Mater. Sci. Technol. 2022, 109, 157–166. [Google Scholar] [CrossRef]
  27. Rybicki, G.C.; Smialek, J.L. Effect of the θ-α-Al2O3 transformation on the oxidation behavior of ß-NiAl + Zr. Oxid. Met. 1989, 31, 275–304. [Google Scholar] [CrossRef]
  28. Yang, J.C.; Schumann, E.; Levin, I.; Rühle, M. Transient oxidation of NiAl. Acta Mater. 1998, 46, 2195–2201. [Google Scholar] [CrossRef]
  29. Brumm, M.W.; Grabke, H.J. The oxidation behaviour of NiAl-I. Phase transformations in the alumina scale during oxidation of NiAl and NiAl-Cr alloys. Corros. Sci. 1992, 33, 1677–1690. [Google Scholar] [CrossRef]
  30. Peng, X.; Li, T.; Pan, W.P. Oxidation of a La2O3-Modified Aluminide Coating. Scr. Mater. 2001, 44, 1033–1038. [Google Scholar] [CrossRef]
  31. Yan, K.; Guo, H.B.; Gong, S.K. High-temperature oxidation behavior of minor Hf doped NiAl alloy in dry and humid atmospheres. Corros. Sci. 2013, 75, 337–344. [Google Scholar] [CrossRef]
  32. Peng, X.; Clarke, D.R.; Wang, F.H. Transient-alumina transformations during the oxidation of magnetron-sputtered CoCrAl nanocrystalline coatings. Oxid. Met. 2003, 60, 225–240. [Google Scholar] [CrossRef]
  33. Peng, X.; Li, M.F.; Wang, F.H. A novel ultrafine-grained Ni3Al with increased cyclic oxidation resistance. Corros. Sci. 2011, 53, 1616–1620. [Google Scholar] [CrossRef]
  34. Huang, Y.; Peng, X. The promoted formation of an α-Al2O3 scale on a nickel aluminide with surface Cr2O3 particles. Corros. Sci. 2016, 112, 226–232. [Google Scholar] [CrossRef]
  35. Doychak, J.; Smialek, J.L.; Mitchell, T.E. Transient oxidation of single-crystal β-NiAl. Metall. Mater. Trans. A 1989, 20, 499–518. [Google Scholar] [CrossRef]
  36. Doychak, J.; Rühle, M. TEM studies of oxidized NiAl and Ni3Al cross sections. Oxid. Met. 1989, 31, 431–452. [Google Scholar] [CrossRef]
Metals 13 01461 g001
Figure 1. The commercial powders: (a) pre-alloyed Ni-Al and (b) pure Ni used for LMD trials.
Figure 1. The commercial powders: (a) pre-alloyed Ni-Al and (b) pure Ni used for LMD trials.
Metals 13 01461 g001
Metals 13 01461 g002
Figure 2. (a) Schematic of additive manufacturing using the LMD method. (b) Test equipment for LMD trials.
Figure 2. (a) Schematic of additive manufacturing using the LMD method. (b) Test equipment for LMD trials.
Metals 13 01461 g002
Metals 13 01461 g003
Figure 3. Schematic diagram of liquid metal solidification process in Ni-Al system [6].
Figure 3. Schematic diagram of liquid metal solidification process in Ni-Al system [6].
Metals 13 01461 g003
Metals 13 01461 g004
Figure 4. XRD patterns of the as-printed (a) Ni-35Al, (b) Ni-32Al, (c) Ni-30Al, and (d) Ni-28Al intermetallic alloys.
Figure 4. XRD patterns of the as-printed (a) Ni-35Al, (b) Ni-32Al, (c) Ni-30Al, and (d) Ni-28Al intermetallic alloys.
Metals 13 01461 g004
Metals 13 01461 g005
Figure 5. Typical OM microstructures of the surface (close to the top layer of the as-printed cube and parallel to the XOY plane) of the (a–c) Ni-35Al, (d–f) Ni-32Al, (g–i) Ni-30Al, and (j–l) Ni-28Al β/γ′ dual-phase Ni-Al intermetallic alloys. (b,c,e,f,h,i,k,l) are magnified morphologies of the areas framed in (a,d,g,j), respectively.
Figure 5. Typical OM microstructures of the surface (close to the top layer of the as-printed cube and parallel to the XOY plane) of the (a–c) Ni-35Al, (d–f) Ni-32Al, (g–i) Ni-30Al, and (j–l) Ni-28Al β/γ′ dual-phase Ni-Al intermetallic alloys. (b,c,e,f,h,i,k,l) are magnified morphologies of the areas framed in (a,d,g,j), respectively.
Metals 13 01461 g005
Metals 13 01461 g006
Figure 6. (a) Oxidation kinetics and (b) corresponding parabolic plots of four LMD β/γ′ Ni-Al intermetallic alloys for 20 h of oxidation in air at 1000 °C.
Figure 6. (a) Oxidation kinetics and (b) corresponding parabolic plots of four LMD β/γ′ Ni-Al intermetallic alloys for 20 h of oxidation in air at 1000 °C.
Metals 13 01461 g006
Metals 13 01461 g007
Figure 7. XRD patterns of (a) Ni-32Al and (b) Ni-28Al after 20 h of oxidation in air at 1000 °C.
Figure 7. XRD patterns of (a) Ni-32Al and (b) Ni-28Al after 20 h of oxidation in air at 1000 °C.
Metals 13 01461 g007
Metals 13 01461 g008
Figure 8. Surface SEM morphologies of (a) Ni-32Al and (b) Ni-28Al β/γ′ intermetallic alloys after 20 h of oxidation in air at 1000 °C. Typical protrusion and concave areas framed with dash squares, labeled as A and B respectively.
Figure 8. Surface SEM morphologies of (a) Ni-32Al and (b) Ni-28Al β/γ′ intermetallic alloys after 20 h of oxidation in air at 1000 °C. Typical protrusion and concave areas framed with dash squares, labeled as A and B respectively.
Metals 13 01461 g008
Metals 13 01461 g009
Figure 9. Cross-sectional SEM morphologies of (a) Ni-32Al and (b) Ni-28Al β/γ′ intermetallic alloys after 20 h of oxidation in air at 1000 °C.
Figure 9. Cross-sectional SEM morphologies of (a) Ni-32Al and (b) Ni-28Al β/γ′ intermetallic alloys after 20 h of oxidation in air at 1000 °C.
Metals 13 01461 g009
Table 1. Overview of the process parameters.
Table 1. Overview of the process parameters.
ParameterValueParameterValue
Laser power (W)800Carrying gas (L/min)8
Scanning speed (mm/min)400Powder feeding speed (r/min)0.15
Laser beam diameter (mm)1.5Preheating temperature (°C)500
Overlapping (mm)1
Table 2. Phase composition, thermally-grown oxides (TGOs), and kp values of the four LMD Ni-Al alloys.
Table 2. Phase composition, thermally-grown oxides (TGOs), and kp values of the four LMD Ni-Al alloys.
AlloyPhase CompositionPhase
Morphology		Oxidation Performance
β (vol.%)γ′ (vol.%)TGOkp (g2/cm4∙s)
Ni-35Al48.151.9fine β, γ′Al2O3(2.1~3.9) × 10−13
Ni-32Al45.954.1
Ni-30Al36.264.3mostly coarse γ′Al2O3,
NiAl2O4, NiO		(1.6~2.0) × 10−12
Ni-28Al25.774.3
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

He, X.; Peng, X.; Fang, J. Study on the Microstructure and High-Temperature Oxidation Performance of β-NiAl/γ′-Ni3Al Intermetallic Compounds Fabricated by Laser Metal Deposition. Metals 2023, 13, 1461. https://doi.org/10.3390/met13081461

AMA Style

He X, Peng X, Fang J. Study on the Microstructure and High-Temperature Oxidation Performance of β-NiAl/γ′-Ni3Al Intermetallic Compounds Fabricated by Laser Metal Deposition. Metals. 2023; 13(8):1461. https://doi.org/10.3390/met13081461

Chicago/Turabian Style

He, Xun, Xiao Peng, and Juan Fang. 2023. "Study on the Microstructure and High-Temperature Oxidation Performance of β-NiAl/γ′-Ni3Al Intermetallic Compounds Fabricated by Laser Metal Deposition" Metals 13, no. 8: 1461. https://doi.org/10.3390/met13081461

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop