Interaction energy between martensitic variants

Recent approaches to the simulation of stress-assisted or strain-induced martensitic transformation in elastic-plastic materials consider the nonlocal dissipation as part of the thermodynamic description of the process. The nonlocal dissipation depends on the material behavior, the loading stress state, and the microstructure. The nonlocal dissipation and the increment in strain energy are investigated for all possible pairs of martensitic variants in an austenitic crystal for selected loading cases by means of the finite element method. For low magnitudes of the applied tensile stress, the interaction energy does not alter significantly with the orientation of the load axis, whereas for higher loading magnitudes, the orientation plays a major role. For a given load stress state, the 24 possible combinations of two martensitic variants yield a set of interaction energies that cannot be split up simply into two groups corresponding to a high and a low interaction level, as proposed in the literature. Comparing the mechanical driving force for a certain pair of variants with the corresponding interaction energy yields a complicated correlation between the two entities.