Atomistic insights on the deformation mechanisms of amorphous/crystalline dual-phase high entropy alloys under nanoindentation

Abstract

The amorphous/crystalline (A/C) dual-phase nanostructured model is an effective method to improve the mechanical properties of high entropy alloys (HEAs). However, the deformation mechanism of the dual-phase HEAs during nanoindentation is still unclear. Here, the effect of the amorphous layer position and thickness on the deformation behavior and mechanical properties of the A/C dual-phase CoCrFeMnNi HEAs under nanoindentation is investigated by molecular dynamics simulation. The results show that the amorphous phase has a significant impact on the mechanical behavior of the HEAs, and the amorphous layer plays a role in absorbing dislocations and hindering their continued movement. The embedding position of the amorphous layer has almost no effect on the elastic deformation of the HEAs. However, during the plastic deformation stage, as the insertion position of the amorphous layer in the HEAs moves downwards, the nanoindentation force of the HEAs shows an obvious increasing trend, which promotes deformation strengthening. The results also indicate that the amorphous layer thickness affects its ability to absorb dislocations, and the dislocation lengths in the HEA with smaller amorphous phase thickness are significantly higher than those in the models with larger amorphous phase thickness.