Formation and migration of thermal vacancies in Ni75Al25−xFex quasi-binaries with different superstructure stabilities: “order–order” kinetics study

Long-range ordering (LRO) kinetics in quasi-binaries Ni75Al25−xFex (0⩽x ⩽15) was investigated by means of isochronal residual resistometry (REST). The effect has been analyzed within the Schulze–Lücke formalism, which yielded separate estimation for vacancy formation EF and migration EM energies being components of the overall activation energy EA for “order–order” kinetics. It has been found that the previously reported decrease of the activation energy for ordering with increasing Fe content is due to a decrease of the vacancy formation energy. The effects of Fe admixture on ordering kinetics are discussed in terms of recent computer simulations.