Molecular dynamics simulation of chemical short-range order strengthening in FCC FeNiCrCoAl x alloys

Chemical short-range order (CSRO) has been regarded as a possible strengthening method for multi-principal element alloys (MPEAs). In our work, Molecular Dynamics (MD) simulation method was used to study the strengthening effect and micro mechanism of CSRO on FCC FeNiCrCoAl x alloys under uniaxial tension. The results demonstrate that the strengthening effect of CSRO is consistent with the change of Al content. CSRO increases the stacking fault energy of FCC FeNiCrCoAl x alloys, reduces the twinning tendency of the alloy, and forms a stacking fault network and Lomer-Cottrell lock that hinder dislocation slip. Besides, CSRO also increases the critical shear stress required for the first Shockley partial dislocation emission. The strengthening effect of CSRO is significant at room and low temperatures. However, although CSRO alloy still has higher yield strength at high temperatures, there is no denser fault network and Lomer-Cottrell lock at the plastic stage.