ON THE KINEMATICS OF INCOHERENT PHASE-TRANSITIONS

Incoherent phase transitions are far more difficult to treat than thei r coherent counterparts. The interface, which appears as a single surf ace in the deformed configuration, is represented in its undeformed st ate by a separate surface in each phase. This leads to a rich but deta iled kinematics, one in which defects such as vacancies and dislocatio ns are generated by the moving interface. We introduce an incoherency tensor that measures the stretching and twisting of one phase relative to the other. We show that incoherency is completely characterized by the incoherency tensor, the vacancy production, and the slip between phases.