Coarsening of skeletal microstructures: Re-examination of data on Pseudo-Skeletal γ′ precipitate coarsening in binary Ni-Al Alloys

Skeletal microstructures are dispersed contiguous phases, morphologically complex and frequently characterized using the average area per unit volume, S–1, which has units of length and is measurable using stereological methods. Results published nearly two decades ago on the kinetics of coarsening of γ′ precipitates in binary Ni-Al alloys are re-examined. The microstructures in those alloys were palpably non-skeletal. S–1 was measured as a function of time to obtain data on the variation of the rate constant for coarsening as a function of γ′ volume fraction. An unfortunate error was made in the conversion of units which negates all the conclusions of that investigation. Re-analysis of those data demonstrates that the equations describing skeletal coarsening kinetics cannot be trusted to provide useful quantitative information on coarsening of non-skeletal microstructures and the role of elastic energy engendered by coherent, misfitting γ′ precipitates.