Estimation of interdiffusivity of the NiAl Phase in Ni–Al binary system

Abstract Interdiffusivity of the NiAl phase in Ni–Al binary system has been estimated as a function of composition in NiAl phase formed on pure nickel using the vapor–solid technique. The calculated results indicate that interdiffusivity in as-formed NiAl phase shows a minimum at about 48 at.% Al, deviating slightly from the stoichiometry. The fact can be explained by the concentration dependence of the thermodynamic factor and the creation of Al-vacancies on the Ni-rich side of stoichiometry. It is observed that activation energy for interdiffusion in the as-formed NiAl phase is particularly sensitive to the presence of constitutional vacancies, which is probably related to the lattice parameter of NiAl phase.