Abnormal indentation behavior of amorphous/crystalline dual-phase Mg alloys: A molecular dynamics simulation

The effect of Y concentration, model size, and indenter radius on the solid-state amorphization and mechanical behavior of the amorphous/crystalline (MgCu)_100-xY_x/Mg dual-phase Mg alloys under nanoindentation is investigated by molecular dynamics simulation. The results indicate that the plastic deformation of the alloys with lower Y concentration is mainly dominated by dislocation slip, while that of the alloys with higher Y concentration is mainly solid-state amorphization. It is worth noting that when the Y concentration in the amorphous phase exceeds a critical value, the abnormal phenomenon occurs in the stage of plastic deformation, that is, the indentation force of the alloys decreases with increasing indentation depth. The results show that the alloys containing high Y concentrations in the amorphous phase exhibit solid-state amorphization near the indenter, which is attributed to the presence of Y atoms promoting a significant increase in the temperature of the amorphous phase during indentation.