THERMODYNAMICS AND HYSTERESIS BEHAVIOR OF THERMOELASTIC MARTENSITIC TRANSFORMATIONS

This work reviews different approaches to the thermodynamics of the martensitic transformation in shape-memory alloys developed in the last years, and attempts to give a general unified version in terms of an energy balance which not only considers equilibrium situations but includes as well the possibility of dissipative effects. The thermoelastic transformation is studied in a quasistatic continuous formalism which results from the assumption that the characteristic relaxation times between thermoelastic equilibrium states are comparatively negligible. The analysis reveals the role of different energy contributions (chemical, elastic and dissipative) in the transformation, and the possibility of their evaluation from calorimetric measurements. Concerning hysteresis, we review the memory properties of partial cycles common to this whole class of systems, and present a number of recent approaches developed to model these properties.