A statistical mechanics approach describing martensitic phase transformation

International audienceA novel theoretical approach modeling martensitic phase transformation is demonstrated in the present study. The generally formulated model is based on the block-spin-approach and on renormalization in statistical mechanics and is applied to a representative volume element which is assumed to be in a local thermodynamic equilibrium. Using fundamental physical properties of a shape memory alloy (SMA) single crystal as input data the model predicts the order parameter "total strain", the martensitic phase fraction and the stress assisted transformation accompanied by pseudoelasticity without the requirement of evolution equations for internal variables and assumptions on the mathematical structure of the classical free energy. In order to demonstrate the novel approach the first computations are carried out for a simple one-dimensional case. Results for total strain and martensitic phase fraction are in good qualitative agreement with well known experimental data according to their macroscopic strain rearrangement when phase transformation occurs. Further a material softening effect during phase transformation in SMAs is predicted by the statistical physics approach