STUDY OF THE THERMOMECHANICAL BEHAVIOR OF SINGLE- AND POLYCRYSTALLINE AMF

The present work describes the thermomechanical behavior of shape memory alloys (SMAs) associated with martensitic transformations. After a brief history of AMFs the thermoelastic properties of these materials are reviewed the various fields of application proving their economic viability are presented and the microstructural aspects of martensitic transformation are detailed. A micromechanical model of the behavior of these materials was then developed. This modeling adapted to the scale of the microstructure description and based on a relatively simple description of the transformation mechanism has made it possible to take account of intra- and intergranular interactions in the expression of the thermodynamic potential established via Gibbs theory. Heterogeneity between the two phases has been neglected and the basic element of the transformation is the deformation associated with the formation of a martensite variant whose volume fraction represents the internal variable involved in defining the potential. Finally the numerical results obtained are discussed.