The effects of elastic stress on coarsening in the Ni-Al system Original Research Article

The effects of elastic stresses on the kinetics of coarsening were investigated. The coarsening of γ′ particles in Ni-Al alloys was quantified by measuring the γ-γ′ interfacial area per volume, instead of a characteristic average particle size. This allowed the kinetics of coarsening to be measured meaningfully at very long times when most particles do not have an equiaxed shape. It was found that the interfacial area per volume follows a t−1/3 rate law, with no change in the exponent or the rate constant even at long coarsening times when elastic energy is a significant contribution to the total energy of the system, and the microstructure is not self-similar. The coarsening rate constant was found to vary with volume fraction as predicted by theory in the absence of elastic stress, in contrast to previous experimental results which quantify coarsening kinetics using an average particle radius.