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High-temperature oxidation behavior of laser additively manufactured AlCrCoNiSi-based high-entropy alloys at 1100 ℃
Guanghua Yan a, Mengyao Zheng b, Jianfeng Gu b, Chuanwei Li b,*
aschool of Construction Machinery, Shandong Jiao Tong University, Jinan 250357, PR China
bInstitute of Materials Modification and Modeling, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China
Abstract:
High-temperature oxidation behavior of two laser additively manufactured AlCrCoNiSi-based high-entropy al loys (Al10 and Al15) are systematically studied in this work. These two alloys exhibit similar oxidation behaviors involving initial linear kinetics oxidation and subsequent parabolic kinetics oxidation at 1100 ℃. However, Al10 alloy has a superior oxidation resistance than Al15 alloy according to the oxidation rate constant. α-Al is the predominant phase of the oxide scales grown on both alloys. Cross-sectional views of the scales show that the scales consist of surface equiaxed grains and underlying columnar grains. For all oxidized alloys, a newly-formed fcc layer forms in the subsurface Al-depletion zone due to the preferential oxidation of aluminum. Al10 alloy exhibits a much thicker newly-formed fcc layer than Al15 alloy after the same oxidation time. This work ascribes the superior oxidation resistance of Al10 alloy to its thick newly-formed fcc layer, which suppresses the outward Al diffusion from the substrate to scale-metal interface by increasing the diffusion distance.
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