A micromechanical model of phase boundary movement during solid-solid phase transformations (Q5947000)

The authors study the propagation of a thermally induced solid-solid phase transformation front in an elastic-plastic medium. A spherically symmetric configuration is considered: a spherically transformed region, starting from a nucleus of a given radius, is embedded into an elastic-plastic infinite solid. The same mechanical and thermal properties are assumed for both phases. The only significant difference is assumed for thermal expansion coefficients. Any inertia forces are neglected during the sphere growth process. The authors consider a sudden initial cooling. The corresponding heat conduction equation includes two heat sources and a moving heat source front coinciding with transformation front and heating by dissipation in current plastic zone. The Green's function technique is applied for the solution of initial-boundary value problem for heat conduction equation. Resulting integral equation is solved numerically. The authors present some results of parameter study in the case of Fe-Ni alloy. The main conclusion is that most of the transformation happens within a very short time interval at the beginning of the process. After some time, a stationary and not static situation is reached. The kind of kinetics is not comparable to kinetics well-known from the literature.