Synergetic effect of Si addition on mechanical properties in face-centered-cubic high entropy alloys; A First-principles study

Tsuru, Tomohito   ; Lobzenko, I.   ; Wei, D.*

High-entropy alloys (HEA) have been receiving increased attention for their excellent mechanical properties. Our recent study revealed that Si-doped face-centered cubic (FCC) HEAs have great potential to improve both strength and ductility. Here, we carried out first-principles calculations in cooperation with Monte Carlo simulation and structural factor analysis to explore the effect of Si addition on the macroscopic mechanical properties. As a result, Si addition increased the local lattice distortion and the stacking fault energy. Furthermore, the SRO formation in Si-doped alloy caused highly fluctuated SF energy. Thus, the heterogeneous solid solution states in which low and high SF regions are distributed into the matrix were nucleated. This unique feature in Si-doped FCC-HEA induces ultrafine twin formation in Si-doped alloys, which can be a dominant factor in improving both strength and ductility.