Cooling rate-dependent microstructure and mechanical properties of AlxSi0.2CrFeCoNiCu1−x high entropy alloys

Abstract The influence of cooling rate on microstructure and mechanical properties of the Al x Si 0.2 CrFeCoNiCu 1− x high entropy alloys (HEAs) were investigated. The alloys were prepared by arc melting (the I x alloys) and injection casting assisted by liquid nitrogen (the R x alloys). Both the phase structure of I x and R x alloys evolved from FCC to FCC + BCC dual-phase, and finally to a BCC phase with an increase in the Al content, and the microstructure transformed from columnar dendrite to equiaxed grain correspondingly. The x range of the R x alloys with dual-phase structure is smaller than that of the I x alloys. The R x alloys also exhibited smaller grain size and spinodal decomposition plate than the I x alloys. Additionally, because of the microstructure refinement and/or phase structure change, both the hardness and yield stress of R x alloys were higher than the I x alloys. The maximum increase rate presented when x  = 0.6, and the minimum one presented when x  = 0.4.