Effects of Y content on the oxidation behavior of CoCrNiAl 0.6 middle entropy alloys at 1200 °C

doi:10.21203/rs.3.rs-3099651/v1

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Effects of Y content on the oxidation behavior of CoCrNiAl 0.6 middle entropy alloys at 1200 °C

https://doi.org/10.21203/rs.3.rs-3099651/v1

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With the increase of the turbine inlet temperature of high-efficiency gas turbines, developing the bond-coat with higher temperature oxidation resistance is also necessary. In the paper, CoCrNiAl_0.6 middle entropy alloys with different content reactive elements Ywere prepared, and the effects of Y content on the microstructure and oxidation behavior at 1200 ℃ were studied. All alloys consist of β phase and γ phase，but CoCrNiAl_0.6Y (0.11) shows some sub-micron γ phase precipitates are within the β phase. The oxidation behavior at 1200 ℃ of CoCrNiAl_0.6Y_x (x=0.05, 0.08, 0.11) confirms that dense oxide scale can be formed at the alloy surface, the surface with aluminum oxide accompanied yttrium oxide makes better adhesion between the matrix and oxide scale. The CoCrNiAl_0.6Y (0.11) alloy has the best oxidation resistance with lower oxidation rate of 5.704×10^-12g²/(cm⁴·s), which is also far better than the conventional NiCoCrAlY alloy with typical compositions.

CoCrNi middle entropy alloy

Reactive elements

High-temperature Oxidation

Oxide scale

The thermal barrier coatings (TBCs) are the “protection suit” of high-efficiency gas turbines. The high temperature oxidation resistance of bond-coat is one of important factors affecting the service life of TBCs[1–3]. Typical NiCoCrAlY (Ni-23%Co-15%Cr-12.5%Al-0.5Y, wt.%)is a widely used commercial bond-coat material[4, 5]. Usually, NiCoCrAlY has excellent oxidation resistance below 1050 ℃, but it is difficult to work stably above 1100 ℃ for a long time[6, 7]. With the increase of the turbine inlet temperature of high-efficiency gas turbines, the bond-coat with higher temperature oxidation resistance is necessary[8].

The research of high-entropy alloys (HEAs) and middle entropy alloys (MEAs) provides a new idea for designing high performance materials, especially, CoCrNi MEA composed of three kinds of elements with equal atomic ratios has better mechanical properties and high temperature resistance than some typical HEAs[9].

Pan et al. studied the thermal oxidation behavior of CoCrNi MEA bond-coat at 750 ℃, the diffusion of cations was significantly slower in the CoCrNi MEA than that in traditional alloys because of the sluggish diffusion and high entropy effect[10]. Agustianingrum et al. studied high-temperature oxidation behaviour of CoCrNi medium-entropy alloy at 900–1100°C, the outward diffusion of metal cations and vacancy formation were suppressed during oxidation as CoCrNi exhibited sluggish diffusion and the high-entropy effect. And after a long exposure time, the oxide layer became unstable and the adhesion between different oxide layers became weak[11]. These findings confirm that CoCrNi MEA shows better high-temperature oxidation behaviour because of the slower diffusion of cations.

Furthermore, an appropriate content of Al in CoCrNi MEA makes sufficient β-NiAl phase to form, the β-NiAl phase is recognized as the oxidation resistant phase to provide Al towards the slow growing alumina scale. However, the β phase shows a ductile-to-brittle transition behaviour, which makes the poor ductility with high Al content of CoCrNi MEA[2, 12]. As reported in our recent work, the Al content has an obvious influence on the mechanical performance and high temperature oxidation behavior, CoCrNi MEA with Al of 0.6 molar ratio show better mechanical performance and oxidation resistance at 1200°C, but the surface oxides spallation was found[13].

In order to improve the adhesion between oxide scale and matrix, the reactive elements such as Y and Hf are widely applied in thermal barrier coatings and superalloys as additive[14, 15]. According to some research, Y can affect the growth rate of oxide scale, and the growth rate of the oxide scale strongly depends on the content, distribution and solubility of reactive elements[16, 17]. Lu et al. studied the oxidation behavior of AlCoCrFeNi_2.1 eutectic high entropy alloy with/without Y doping at 1000°C and 1100°C. The result shows doping of minor Y is crucial to improving the Al₂O₃ scale adhesion and achieving its durability at high temperatures[18]. Lu et al. studied the effects of Y addition on the oxidation resistance of AlMo_0.5NbTa_0.5TiZr refractory high entropy alloys. Y induced the formation of a continuous AlNbO₄-based oxidation scales and reduced the volatile oxidation of Mo. The formation of Y oxides in the interfaces improved the adherence of the oxide scale, and the high content of Y was disadvantageous to resisting the high temperature oxidation[19]. All of these demonstrate the content of Y is critical to improving the high temperature oxidation behaviors.

We have confirmed CoCrNi MEA with Al of 0.6 molar ratio shows better mechanical performance and oxidation resistance at 1200°C, but the spallation of surface oxide scale was found. In order to improve the high temperature oxidation performance of CoCrNiAl_0.6, CoCrNiAl_0.6Y_x (x = 0.02, 0.05, 0.08, 0.11, at. %) alloys were prepared using a vacuum arc melting furnace. The effects of Y content on the CoCrNiAl_0.6 MEAs high-temperature oxidation behavior at 1200°C were discussed. In addition, the typical CoCrNiAlY (Ni-23%Co-15%Cr-12.5%Al-0.5Y, wt.%)alloy was also prepared for comparison.

The doped element Y (≥ 99.9 wt.%) was blended with Co, Cr, Ni and Al metal of high purity (≥ 99.9 wt.%) and placed in a vacuum arc melting furnace with an argon atmosphere to prepare alloy ingots. The CoCrNiAl_0.6 alloy components with different Y content are displayed in Table 1, and meanwhile the conventional NiCoCrAlY alloy with typical compositions was also fabricated for comparison. At the same time, to ensure the uniformity of the alloy composition, the volatile alloy such as Al was placed at the bottom of crucible with re-melted five times, which can control the loss of Al and guarantee the uniformity of elements.

Table 1

The composition of CoCrNiAl_0.6Y_x (x = 0.02, 0.05, 0.08 and 0.11) MEAs
Alloys	Element (at. %)
Alloys	Co	Cr	Ni	Al	Y
CoCrNiAl_0.6Y(0.02)	27.78	27.78	27.78	16.64	0.02
CoCrNiAl_0.6(Y0.05)	27.78	27.78	27.78	16.61	0.05
CoCrNiAl_0.6(Y0.08)	27.78	27.78	27.78	16.58	0.08
CoCrNiAl_0.6(Y0.11) CoCrNiAlY	27.78 19.20	27.78 14.20	27.78 40.94	16.55 22.80	0.11 0.28

The cast ingots were cut into regular samples of size 5 mm×5 mm×2 mm by using an electronic wire cutting machine (DK77 EDM). All specimens were abraded with silicon carbide abrasive papers and polished with a polisher, then these samples were cleaned using deionized water and alcohol in an ultrasonic machine. The weight of these samples was weighed using an electronic balance with one-thousand scale before the cyclic oxidation test. The cyclic oxidation experiments were conducted at 1000°C, 1100°C and 1200°C with air flow rate of 400 ml min^− 1, respectively. And these samples fixed in the crucible were placed in the center of tube furnace. During the cyclic oxidation, these samples were withdrawn from the tube furnace every 10 h and allowed cool naturally to room temperature. The mass change of each sample was recorded after withdrawing each time. The total cyclic times were 6 times and the total oxidation time is 60 h each sample.

A D8A X-ray diffractometer (XRD, German BRUKER company) with Cu Kα1 radiation at 40 kV was used for the phase identification. The spectra were detected with the diffraction angle from 20 ° to 80 ° at a scanning speed of 5 °/min. Field-emission scanning electron microscope (SEM, JSM-7900F), which was equipped with an energy dispersive spectrometer (EDS, EDAX Octance Elect Super) was used to observe and analyze the microstructure and element distribution.

Effect of Y content on microstructure of CoCrNiAl_0.6Y_x MEAs

The morphology and microstructure of CoCrNiAl_0.6Y_x are shown in Fig. 1 (a), (c), (e) and (g). All alloys exhibit dendritic structure with two clear phases. All alloys consist of a dark contrast β phase and a bright contrast γ phase. The microstructure of CoCrNiAl_0.6Y_x shown in Fig. 1 (b), (d) and (f) has not an obvious difference, but some sub-micron γ phase precipitates are observed within the β phase in Fig. 1 (h). The chemical compositions and phase maps in the CoCrNiAl_0.6Y(0.02) and CoCrNiAl_0.6(Y0.11) determined by SEM-EDS are presented in Table 2, Fig. 2 (a) and (b). Generally speaking, Co and Cr can be dissolved in NiAl-based chemistry. The composition limit for Cr induced extension of the β phase field is around 15 at. % in the Ni–Al–X diagram[20]. Cr usually occupies the sites on which Ni or Al is lower in content, and it does not show special preference on Ni and Al sites in the β phase. Because of these, Cr usually has a higher solubility in γ phase than in β phase in a γ + β alloy[16]. Both EDS mapping in Fig. 2 and element distribution in Table 2 confirm that Co and Cr enrich in γ phase, Ni and Al enrich in β phase,

Table 2

Chemical composition of the phases in the CoCrNiAl_0.6Y(0.02) and CoCrNiAl_0.6Y(0.11) determined by EDS point analysis
Alloys	phases
Alloys		Co	Cr	Ni	Al	Y
CoCrNiAl_0.6Y(0.02)	γ	32.36 ± 1.21	29.70 ± 0.95	25.90 ± 1.03	12.00 ± 0.78	0.04 ± 0.02
	β	25.47 ± 1.13	23.32 ± 0.87	28.61 ± 0.98	22.58 ± 0.94	0.02 ± 0.01
CoCrNiAl_0.6(Y0.11)	γ	30.71 ± 1.18	31.38 ± 1.09	24.64 ± 0.95	13.13 ± 0.76	0.14 ± 0.03
	β	21.50 ± 0.97	20.76 ± 0.89	27.09 ± 0.98	30.55 ± 1.16	0.10 ± 0.02

The white precipitates are observed at γ/β phase boundaries resulting from the extremely low solubility of Y. The higher Y content, the more precipitates at the grain boundaries, and the higher Y content, the more obvious sub-micron γ phase precipitates within the β phase. Usually, the β phase preferentially nucleates and grows during the solidification process, the γ phase forms during cooling. The β phase reacts with the residual liquid metal (L) as follow: L + β → γ, and the residual liquid metal will be rich in Y because the solubility of Y in the β phase is lower than that in γ phase. As a result, the sub-micro γ-phase precipitates forms within the primary β phase via peritectic reaction[2, 21], and the higher Y content, the more obvious sub-micron γ phase precipitates within the β phase.

Figure 3 shows XRD diffraction patterns of CoCrNiAl_0.6Y(0.02) and CoCrNiAl_0.6(Y0.11) MEAs, these alloys form duplex FCC plus BCC phase structure[2, 22], which is consistent with the SEM results.

Effect of Y content on oxidation behavior of CoCrNiAl_0.6Y_x MEAs

Figure 4 shows the surface macromorphology of CoCrNiAl_0.6Y_x MEAs after cyclic oxidation experiments for 60 h at 1000°C, 1100°C and 1200°C, respectively. All metals changed the color into gray after oxidation for 60 h at 1000°C, 1100°C and 1200°C, the metallic luster disappeared. The surface oxides spallation did not been found in these metals.

The mass change of each sample was recorded in the process of cyclic oxidation. After cyclic oxidation experiments for 60 h at 1000°C and 1100°C, there are little mass change in these samples. The oxidation kinetic curves after cyclic oxidation experiments for 60 h at 1200°C follow a parabolic rate law. Figure 5 is the oxidation kinetic curves of CoCrNiAl_0.6Y_x during cyclic oxidation experiment for 60 h at 1200°C. It is clearly observed the Y content has an obvious influence on the relative oxidation resistance. Based on the oxidation kinetic curve of CoCrNiAl_xY alloy at 1200°C, we can find the obvious mass gain of CoCrNiAl_0.6Y_x (x = 0.02, 0.05 and 0.08) in the early oxidation stage. For CoCrNiAl_0.6Y (0.11) alloy, the weight gain tends to be gentle in the first 10 h. All these samples have a relative gentle weight gain from 10 h to 60 h. The weight gain of CoCrNiAl_0.6Y_x with Y content of 0.02, 0.05, 0.08 and 0.11 are 0.00178, 0.00163, 0.00146 and 0.00111 g/cm², respectively.

The growth of oxide scale follows a parabolic law at 1200°C and conforms with the classical oxidation theory during cyclic oxidation. Wagner established the parabolic kinetic law of oxide film[23], and pointed out that the diffusion of positive and negative ions through the formed oxide film was the key rate-controlling step of metal oxidation. The oxidation kinetic curves followed a parabolic rate law. The following is the equation of parabolic rate law.

(∆m/A)²=K_pt (1)

∆m, A and K_p are the quality gain, the surface area of samples and parabolic rate constants.

Based on the parabolic rate law, the calculated oxidation rate constants of CoCrNiAl_0.6Y_x (x = 0.02, 0.05, 0.08 and 0.11) are 1.467×10^− 11, 1.230×10^− 11, 9.87×10^− 12 and 5.704×10^− 12 g²/(cm⁴·s), respectively. The CoCrNiAl_0.6Y (0.08) alloy have a lowest mass change and oxidation rate constant.

Because CoCrNiAl_0.6Y_x alloys involve volatile metal oxides during the high temperature oxidation, only the macromorphology and oxidation mass gain curve cannot reflect the real oxidation situations effectively. Therefore, the microstructure characteristics were further investigated.

Figure 6 shows XRD spectra of CoCrNiAl_0.6Y_x alloys after cyclic oxidation experiments for 60 h at 1200°C. The oxide scale of CoCrNiAl_0.6Y (0.02) consists of γ phase, Al₂O₃ and Cr₂O₃[22]. The diffraction peaks of CoCrNiAl_0.6Y_x(x = 0.05, 0.08, 0.11) with higher Y content at 39.6°, 42.2°, 46° and 49° are identified to be Y oxides (JCPDS 88-1040)[24]. Besides the Y oxides, the diffraction peaks of γ phase and Al₂O₃ also appear on the CoCrNiAl_0.6Y_x (x = 0.05, 0.08, 0.11).

The microstructure of CoCrNiAl_0.6Y_x after cyclic oxidation experiments for 60 h at 1200°C was observed. Figures 7 and 8 display the surface microstructure and EDS maps of cyclic oxidation experiments for 60 h at 1200°C. There is an obvious difference on the surface morphology and microstructure of these metal with different Y contents. The surface morphology of CoCrNiAl_0.6Y (0.02) as shown in Fig. 7 (a) that the spallation can be found on the surface. Besides the spallation, the oxide scale consists of bright phase and dark phase. The dark phase is the major phase in the CoCrNiAl_0.6Y (0.02) alloy. When more Y is added in the CoCrNiAl_0.6 alloy, the oxide scale morphology looks like a map, and it consists of two distinct phases. As the Y content increases, the bright phase is the major phase. As seen from the microstructure of CoCrNiAl_0.6Y_x in Fig. 7 (a), (b), (c) and (d), the dark phase of oxide scale consists of granular oxides, the oxide scale on the bright phase is of webbed structure. Combine the EDS maps with the microstructure in Fig. 8 (a), (b), (c) and (d), the content of Y in the bright phase is higher, the content of Al is higher in the dark phase. We can infer the bright phase majorly consists of yttrium oxide, and the dark phase majorly consists of aluminum oxide. And aluminum oxide enriched phase originates from the β phase before oxidation, yttrium oxide enriched phase originates from the γ phase. There is a large area of γ phase in the CoCrNiAl_0.6(Y 0.11) alloy, which makes a larger area of yttrium oxide enriched phase after high temperature oxidation.

Figure 9 and Fig. 10 display the cross profiles and EDS maps of CoCrNiAl_0.6Yx MEAs after cyclic oxidation experiments for 60 h at 1200°C. The cross profiles with a lower magnification of CoCrNiAl_0.6Y_x (x = 0.02, 0.05 and 0.08) in Fig. 9 (a), (c) and (e) show a discontinuous internal Al₂O₃ scale, the CoCrNiAl_0.6Y (x = 0.11) in Fig. 9 (g) show the best continuity of the Al₂O₃ scale. The CoCrNiAl_0.6Y_x (x = 0.05, 0.08 and 0.11) with a higher Y content form the dense oxide scale with a small amount of Y oxides protrusion along the scale oxides interfaces. The thickness of Al₂O₃ scale in these alloys is 3.61, 3.17, 3.06 and 2.99 µm, respectively.

The cross-section EDS mappings of these samples in Fig. 10 show that Al-rich β phase is highly depleted close to the Al₂O₃ scale because of the surface oxidation after cyclic oxidation at 1200°C. The diffusion of Al from the alloy matrix to the surface and the enrichment of Cr at the alloy matrix-oxide scale interface are the key factors causing the microstructure changes near the alloy matrix-oxide scale interface. The main microstructure changes are the formation of β-depletion zone near the alloy matrix-oxide scale interface. For the CoCrNiAl_0.6Y (0.02) alloy, an internal Al₂O₃ scale along with an external layer of Cr₂O₃ is formed on the surface of alloy. For CoCrNiAl_0.6Y_x (x = 0.05, 0.08, 0.11) alloys, an external layer of Al₂O₃ with Y oxides is formed. Y is preferably distributed along the Al₂O₃ scale surface and internal interfaces; it is believed that the outward segregation of Y takes place along easy diffusion paths such as phase boundaries in the process of the oxidation and participate in the oxidation. At the same time, the inward diffusion of oxygen along grain boundaries also happens. Obviously, there are a little more Y oxides along the scale oxides interfaces with the higher Y content for the CoCrNiAl_0.6Y_x (x = 0.08 and 0.11).

Usually, the activation energy of metal oxides is less than zero, which will be oxidized spontaneously. And the lower the activation energy is, the easier the oxidation spontaneous reaction is. In the CoCrNiAl_0.6Y_x MEAs, Al, Cr and Y have a relative lower activation energy. In the early oxidation stage, abundant oxygens are distributed around the alloy matrix, and the oxidation reaction is controlled by the interface metal. For the CoCrNiAl_0.6Y (0.02) alloy with the lower Y content, the major oxides are Al oxides and Cr oxides. When CoCrNiAl_0.6Y_x (x = 0.05, 0.08, 0.11) alloys with the higher Y content, Y and Al elements distributed on the interface are easily be oxidized based on the lower activation energy of metal oxides in the early oxidation stage. The formation of Al₂O₃ accompanied by the oxidation of a part of the Y at the surface during initial oxidation. The further oxidation reaction is controlled by the diffusion of oxygen and metal element, and the diffusion rate of element will decide the oxidation rate of alloys. As confirmed by calculation [25], Al in Ni matrix has the largest interdiffusion coefficient in most cases, so the dense Al₂O₃ scale can be formed.

Since Y in the CoCrNiAlY metal is the element that forms the most stable oxide. The location of the oxidized Y after initial oxidation is also determined by two processes that occur simultaneously. The first process is the segregation of Y at the metal surface where it is oxidized. The second process that affects the initial distribution of Y in the oxide scale is the diffusion of oxygen into the metal, which causes the Y to oxidize internally in the metal. Refer to the microstructure of CoCrNiAl_0.6Y_x MEAs before oxidation, there are the more obvious sub-micron γ phase precipitates within the β phase and Y segregation at the phase boundaries with higher Y content. It can also explain that there is more segregation of Y at the metal surface with higher Y content. A larger amount of segregated Y towards the metal surface can be promoted by oxidation at higher temperatures. These can explain the surface microstructure of CoCrNiAl_0.6Y_x after cyclic oxidation at 1200°C, the area of Y oxides of CoCrNiAl_0.6Y_x with lower Y content is small. When the content of Y is 0.11 at. %, Y oxides almost cover the whole surface. And the sample with higher Y content, Y oxides along the inner of the oxide scale can also be observed. The depth at which the Y oxidizes internally is determined by the competition between the diffusion of Y towards the alloy surface and the diffusion of oxygen into the matrix. At high temperatures the outward segregation of Y is dominant and the extent of the internal oxidation zone is relatively small[15, 26].

Usually, when the reactive-element with low content is homogeneously distributed, it will segregate to the the oxide-matrix interface and oxide scale surface because of its solubility in the alloy[27, 28]. In this case, the oxidation rate of the alumina is reduced because of the blocked inward diffusing of oxygen along oxide grain boundaries. However, if the reactive-element with high content which is higher than the solubility limit, it is mainly heterogeneously confined within the alloy as a separate phase. Therefore, the reactive element is mostly present as oxide protrusions in the oxide scale after oxidation and the growth rate of the scale is increased.

In general, the growth rate of the oxide scale of CoCrNiAl_0.6Y_x (x = 0.02, 0.05, 0.08 and 0.11) is slow which originates from the sluggish diffusion and the high-entropy effect of CoCrNi MEA alloy. For the CoCrNiAl_0.6Y_x (x = 0.05, 0.08 and 0.11) alloy, the reactive-element mainly segregate to the oxide scale surface, only a small amount Y oxide protrusions form in the interface of alumina scale, and CoCrNiAl_0.6Y (0.11) show the more Y oxide in the oxide scale surface. The growth rate of the scale of CoCrNiAl_0.6Y (0.11) is slow obviously based on the oxidation kinetic curves and cross profiles compared with the alloys with lower Y content. The major reason should be the formation of a dense aluminum oxide scale accompanied by the more Y oxide in the oxide scale surface during initial oxidation, which make the very low diffusivity of both aluminum and oxygen through this scale. Therefore, the CoCrNiAl_0.6Y (0.11) has the best oxidation resistance.

Comparing with the conventional NiCoCrAlY alloy with typical compositions

Figure 11 is the oxidation kinetic curves and cross section profiles of CoCrNiAl_0.6Y (0.11) and the conventional NiCoCrAlY alloy with typical compositions after cyclic oxidation for 60 h at 1200°C. The weight gain of CoCrNiAl_0.6Y (0.11) and the conventional NiCoCrAlY alloy are 0.00111 and 0.00456 g/cm², respectively. The corresponding oxidation rate constant are 5.704×10^–12 and 9.627×10^–11 g²/(cm⁴·s), respectively. The thickness of oxide scale of CoCrNiAl_0.6Y (0.11) and the NiCoCrAlY alloys is 2.99 and 4.15 µm, respectively.

These results confirm that CoCrNiAl_0.6Y (0.11) also has a much better oxidation resistance performance than the conventional NiCoCrAlY alloy with typical compositions.

In the present study, the oxidation behavior of CoCrNiAl_0.6Y_x (x=0.02, 0.05, 0.08, 0.11) MEAs was systematically investigated at 1200 °C, and the oxidation resistance performance of CoCrNiAl_0.6Y (0.11) was compared with the conventional NiCoCrAlY alloy.

CoCrNiAl_0.6Y_x MEAs consist of β phase and γ phase, and CoCrNiAl_0.6Y (0.11) shows some sub-micron γ phase precipitates are within the β phase. The Y precipitates are distributed at γ/β phase boundaries.
The cross profiles at 1200 ℃ of all alloys confirms that oxide scale can be formed at the alloy surface, and the dense oxide scale can be formed at the CoCrNiAl_0.6Y_x (x= 0.05, 0.08, 0.11) alloy surface. The thickness of oxide scale of CoCrNiAl_0.6Y_x (x= 0.02, 0.05, 0.08, 0.11) alloys is 3.61, 3.17, 3.06 and 2.99 µm, respectively.
With the increase of Y content, Y segregates as ions to the oxide-matrix interface and oxide scale surface, only a small amount Y oxide protrusions form in the interface of alumina scale. The surface with aluminum oxide accompanied yttrium oxide makes better adhesion between the matrix and oxide scale.
The CoCrNiAl_0.6Y (0.11) alloy has the best oxidation resistance with lower oxidation rate of 5.704×10^-12g²/(cm⁴·s), which is also far better than the conventional NiCoCrAlY alloy with typical compositions.

Author Contributions D. Y. Deng, X. X. Xiong and H. Q. Wen did the experimental work and wrote the draft. Y. G. Tong, J. Liu, and Z. H. Cai co-supervised the work and edited the draft. All authors reviewed the manuscript.

Funding This work was supported by National Natural Science Foundation of China (No. 92166105), and The Science and Technology Innovation Program of Hunan Province (No. 2021RC3096).

Conflict of interest The authors have no relevant financial or non-financial interests to disclose

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Effects of Y content on the oxidation behavior of CoCrNiAl 0.6 middle entropy alloys at 1200 °C

Status:

Version 1

Abstract

Figures

Introduction

Experimental Procedures

Results and discussions

Effect of Y content on microstructure of CoCrNiAl_0.6Y_x MEAs

Effect of Y content on oxidation behavior of CoCrNiAl_0.6Y_x MEAs

Comparing with the conventional NiCoCrAlY alloy with typical compositions

Conclusions

Declarations

References

Additional Declarations

Status:

Version 1

Effects of Y content on the oxidation behavior of CoCrNiAl 0.6 middle entropy alloys at 1200 °C

Status:

Version 1

Abstract

Figures

Introduction

Experimental Procedures

Results and discussions

Effect of Y content on microstructure of CoCrNiAl0.6Yx MEAs

Effect of Y content on oxidation behavior of CoCrNiAl0.6Yx MEAs

Comparing with the conventional NiCoCrAlY alloy with typical compositions

Conclusions

Declarations

References

Additional Declarations

Status:

Version 1

Effect of Y content on microstructure of CoCrNiAl_0.6Y_x MEAs

Effect of Y content on oxidation behavior of CoCrNiAl_0.6Y_x MEAs