Nanoindentation into a bcc high-entropy HfNbTaTiZr alloy—an atomistic study of the effect of short-range order

Abstract

The plastic response of the Senkov HfNbTaTiZr high-entropy alloy is explored by means of simulated nanoindentation tests. Both a random alloy and an alloy with chemical short-range order are investigated and compared to the well understood case of an elementary Ta crystal. Strong differences in the dislocation plasticity between the alloys and the elementary Ta crystal are found. The high-entropy alloys show only little relaxation of the indentation dislocation network after indenter retraction and only negligible dislocation emission into the sample interior. Short-range order—besides making the alloy both stiffer and harder—further increases the size of the plastic zone and the dislocation density there. These features are explained by the slow dislocation migration in these alloys. Also, the short-range-ordered alloy features no twinning plasticity in contrast to the random alloy, while elemental Ta exhibits twinning under high stress but detwins considerably under stress relief. The results are in good qualitative agreement with our current knowledge of plasticity in high-entropy alloys.

First-principles calculations of mechanical properties of TiZrNbTaMo series biological refractory high-entropy alloys

“…High-entropy alloys (HEAs) 1,2 break the traditional concept of single-principal element design by focusing on configurational entropy rather than mixing enthalpy. This approach creates multi-principal metallic materials with excellent mechanical, physical, and chemical properties, expanding the potential for new material development [3][4][5] . In biomedical implant materials, HEAs have a hardness similar to bone, higher specific strength, better corrosion and wear resistance.…”