Effects of heat treatment on the microstructure, wear behavior and corrosion resistance of AlCoCrFeNiSi high-entropy alloy

Abstract

The effects of heat treatment on the microstructure, wear behavior and corrosion resistance of AlCoCrFeNiSi high-entropy alloy were investigated. Results indicate that the phase composition of as-cast alloy includes disordered body-centered cubic (BCC) solid solution phase, ordered BCC phase (B2), Cr3Si and (Cr, Ni, Si)-phase. The system exhibits a good thermal stability and no phase transition occurs after heat treatment except the change of diffraction peak intensity and the appearance of weak peak. After heat treatment, the dendrites of B2 phase turns into discontinuous spherical particles, the BCC interdendrite region narrows, and the short rod-like precipitation Cr3Si phase is transformed into long needle-like microstructure. The highest compression fracture strength and strain are 1752 MPa and 11.8 % at 1150-2 h, which are 36 % and 19 % higher than the as-cast alloy, respectively. At 1150-2 h, the highest microhardness (1004.3 HV0.5) and lowest friction coefficient (0.115) are obtained, which are 1.2 times and 3.4 times better than that of as-cast alloy. A mixed mechanism of abrasive and oxidative wear are occurred during friction and deformation. Heat treatment of 1100–2 h possesses the optimal corrosion resistance with the Ecorr and Icorr of −330.776 mV and 637.587 nA due to the appearance of weak passivation phenomenon.