Solute-Vacancy Interactions in Nickel

Abstract

ABSTRACTSolute trapping of vacancies in a Ni host lattice is a first step to understanding how solute additions may effect ordering phase transformation in Ni-based alloys. Minor additions of solutes (<3 wt.%) may not have an appreciable effect on the thermodynamics of phase stability but strong binding between the vacancy and solute may significantly alter the kinetics of phase transformations. In this work vacancy-solute binding energies are calculated for multiple elements (Cr, Fe, Mn, Si, Ti, Nb, Ta, Cu, Al, Mo) in a pure Ni face-centered cubic lattice. These elements are common in corrosion-resistant Ni-based alloys. Binding enthalpies for the first four nearest-neighbor vacancy-solute pairs are reported for all elements. The results of this study show that Si, Ti, Nb and Ta bind to vacancies in the first nearest-neighbor position. Alloys containing these solute additions may experience delayed phase transformation due to vacancy trapping that slows diffusion.