MICROMECHANICS-BASED MODELING OF 2-WAY MEMORY EFFECT OF A SINGLE-CRYSTALLINE SHAPE-MEMORY ALLOY

A micromechanics-based Helmholtz free energy is obtained. Then, in the framework of irreversible thermodynamics, a kinetic relationship, a m artensitic nucleation criterion and the reorientation criterion of mar tensitic variants are obtained. These relationships are valid for a th ree-dimensional proportional or non-proportional mechanical loading or a combination of mechanical and thermal loading. The two-way memory e ffect is simulated and compared quantitatively with experimental resul ts. This simulation is based on the assumption that mechanical dissipa tion of active variants decreases during cycling (training). Copyright (C) 1997 Acta Metallurgica Inc.