Deformation mechanisms of TRIP–TWIP medium-entropy alloys via molecular dynamics simulations

•Less Shockley partial dislocations (SPDs) are observed as the grain size decreases, which may be due to the transformation from intragranular to intergranular evolutionary mechanisms within a nanoscale range.•Stacking faults are markedly suppressed as the average grain size decreases.•The interaction of cluster defects with the SPDs produces a promoting effect on the nucleation of stacking faults.•Dislocation nucleation rate seems to be increased as a linear relationship following the increase in the grain sizes.