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In this paper, Ti41V27Hf11.5Nb11.5Cr3Al6 RHEA with a yield strength of ~1 178 MPa and a tensile plasticity of ~19.5% is obtained. The Cr and Al alloys significantly improve the oxidation resistance of the alloys by forming a protective oxide layer and eliminate severe spalling at high temperatures, which provides an opportunity to design new RHEAs.
Refractory high-entropy alloys (RHEAs) have attracted a lot of attention for their ability to maintain significant yield strength at very high temperatures. However, room-temperature fragility and inadequate high-temperature oxidation resistance often limit the application of body-centered cubic (BCC) RHEAs. The addition of antioxidant elements to RHEAs is a promising way to achieve high-temperature oxidation, but it often promotes the formation of brittle phases and reduces room-temperature ductility.
目前，RHEA研究热潮已使部分合金表现出优异的应用价值。 基于此，西北工业大学何峰教授研究团队利用Cr和Al元素的固有特性，开发了一种具有优异力学性能的新型Ti41V27Hf11.5Nb11.5Cr3Al6 RHEA，并提高了其抗氧化性。 研究结果以题为“Uniting superior mechanical properties with oxidation resistance in a refractory high-entropy alloy via Cr and Al alloying”发表于期刊《Scripta Materialia》。
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Through composition adjustment, an appropriate amount of Cr and Al was added to the alloy to form a nanoscale spinodal structure, and the yield strength was increased to 1 178 MPa. At the same time, due to the pinning impact of the spinodal structure, the formation of dislocations is caused. The intricate dislocations guarantee good work hardening capacity, resulting in an elongation of around 19.5%. Due to the formation of protective Cr2O3 and Al2O3 layers, the degree of spalling is reduced, and the oxidant resistance of CrAl RHEA is significantly improved at 1 000 °C.
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