Effects of different Al contents on mechanical properties and high temperature oxidation resistance of AlxCoCr0.6NiV0.6 high entropy alloy
Wu Da, Bo Li, Yuzhi Shi, Xiaohu Hou, Cong Li, Yimin Gao, Pucun Bai, Yao Liu, Chenyu Liang
Abstract
High-entropy alloys with a single-phase FCC structure are widely employed as structural materials due to their excellent ductility and plasticity. Nevertheless, the strength and oxidation resistance of single-phase FCC alloys remain inadequate. Conventional methods for enhancing strength often compromise plasticity, rendering them unsuitable for engineering applications. This study presents a strategy for the preparation of CoCrNi-based AlxCoCr 0.6 NiV 0.6 alloys, characterized by unequal atomic ratios and high entropy, incorporating aluminum and vanadium. Short-range order was observed in each alloy composition, varying in size and crystal plane families. At an aluminum content of x = 0.85, both FCC and BCC dual phases were present in the alloy. The heterogeneous structure and dual-phase presence significantly enhanced the strength and high-temperature oxidation resistance of the high-entropy alloy. The yield strength of the high-entropy alloy increased from 235 MPa to 974 MPa, while the oxide layer thickness decreased from 37.5 μm to 8.3 μm, representing a reduction of 77 %. This study provides a method for adjusting the cross-scale heterostructures in high-entropy alloys (HEAs) and guides the design of CoCrNi-based HEAs with high strength, high ductility, and excellent antioxidant properties.