Shape Deforming Phase Transition in Solids: Energetics and pseudoelasticity

Abstract

Martensitic transformations are shape-deforming phase transitions which can be induced in certain alloys as a result of changes in the imposed strains, stresses or temperatures. The interest in these alloys, which undergo a shape-deforming phase transition from a high temperature phase (austenite) to a low temperature phase (martensite), stems in part from their applicability as elements in active structures. In the present text we outline three recent theories concerning the energy transfers that accompany and determine the martensitic phase change. In §1 we will thus mention the pseudoelastic hysteresis in shape-memory wires and the corresponding treatment of (Leo et al .,1993; Bruno et al .,1995). In §2 we will present some aspects of the discussion of (Bruno et al. ,1996) on equilibrium configurations in polycrystalline martensites. In §3 finally we will describe a computation (Bruno, 1997) which explains typical microstructural lengthscales observed in single-crystalline martensites as resulting from an interplay between elastic energies and dissipative mechanisms.

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