A MODEL OF PHASE TRANSITION FROM AUSTENITE TO MARTENSITE IN SINGLE-CRYSTAL NIMNGA ALLOYS

摘要

A model is presented for the description of shape memory effect due to thethermoelastic martensite transformation induced by temperature,stress and magneticfield in ferromagnetic NiMnGa alloys.A cosine model on the basis ofthermodynamic principle is developed to describe the structural distortion of thelattice in the complex coupled field.The magnetic-field-induced stress is introducedand the equivalence principal is employed for the mechanical and magnetoelasticdeformation to represent the reorientation of the martensitic variants.Thecomparison between the theoretical and experimental results shows that the theoryprovides a good quantitative description of the material peculiar behavior.