Experimental Determination of Vacancy Formation Energies in Multicomponent Systems

Abstract

‘Sluggish diffusion’ is probably the most debated aspect of the high entropy alloys in the literature over the past decade but there is almost complete absence of data on the energetics of lattice defects such as vacancies in these alloys. The present work reports the measurements of the enthalpies of vacancy formation $({\Delta H}_{f}^{v})$by residual resistivity technique for binary Fe−45.3 at. pct Ni, ternary Fe−16 at. pct Cr–19 at. pct Ni, quaternary equiatomic Fe–Ni–Cr–Co, and quinary equiatomic Fe–Ni–Cr–Co–Mn alloys. It is observed that the enthalpy of vacancy formation increases from the studied binary to quinary alloys. A qualitative analysis is presented for understanding the role of the binary enthalpies of mixing $({\Delta H}^{\text{mix}})$ of constituent elements on the enthalpy of vacancy formation. It is discerned that ${\Delta H}_{f}^{v}$ is governed more by the type of constituent elements rather than mere number of components.