Operational nucleation in martensitic transformations

Operational nucleation in martensitic transformations is accessible to measurement and governs the reaction kinetics. In essence, it involves the growth start-up of preexisting embryos, and is not concerned with the origin of such embryos. Another important feature is the fast chain-of-events triggered-off after the growth is initiated, leading to the sudden formation of observable martensitic plates. The model of operational nucleation and subsequent growth presented here provides a plausible explanation of the fine-scale phenomena, and permits calculation of the aspect ratio (or growth path) adopted by the advancing particle. E. C. Bain had a long-standing interest in the nature of martensitic nucleation. By strange coincidence, this was the subject of my last conversation with him.