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Evolution of mechanical properties and corrosion resistance of Al0.6CoFeNiCr0.4 high-entropy alloys at different heat treatment temperature

2020; Elsevier BV; Volume: 244; Linguagem: Inglês

10.1016/j.matchemphys.2020.122700

1879-3312

Shuai Wang, Yuhong Zhao, Xiaotao Xu, Cheng Peng, Hua Hou,

Advanced materials and composites

The non-equiatomic Al0.6CoFeNiCr0.4 HEA with dual FCC + BCC structure was fabricated by arc-melting under high-purity argon atmosphere, and the mechanical behavior and corrosion resistance of these HEAs with heat temperature range of 550 °C–850°Cfor 24 h were investigated. By increasing the ageing temperature, the crystalline phase of these HEAs transformed from FCC + disordered BCC to FCC + disordered BCC + order B2 phase, and then to FCC + order B2 phase.The spherical B2 was firstly observed in the aged- 650°CHEA, and disordered BCC disappeared in aged-850°CHEA. The ageing hardening occurred at aged-650 °C, because of the growth of disordered BCC phase (α-Fe) and precipitation of spherical B2 phase (AlNi). Additionally, it can be found that the proper spinodal decomposition of FCC phase (Fe–Cr) can optimize mechanical properties of alloys, while excessive spinodal decomposition will cause the negative effect. The aged-750°Cdisplay an excellent mechanical properties of high strength and compress ductility due to the presence of proper spinodal decomposition and spherical B2 phase precipitation. When these HEAs were immersed in the 3.5 wt% NaCl solution, the corrosion resistance of these HEAs are gradually decrease with the Volume fraction of B2 phase increase, suggesting that crystalline phases with higher amount of Al element are prone to be corroded by Cl-ion.