THEORY AND MODELING OF THE MARTENSITIC-TRANSFORMATION

A status is made of the understanding of the martensitic transformation based on studies of the bcc-hcp model systems. The results of first principle calculations and recent neutron scattering experiments will be compared. Dynamical precursor phenomena are found in the purest available systems. An incomplete softening of elastic constants is observed supporting the mechanism for the martensitic first order transition in terms of a free energy expansion in uniform and in internal strains. The construction of simple analogue spin models is critically discussed and results of Monte Carlo simulations presented. Finally, is the result of studies of the domain growth kinetics after quenches to low temperature discussed. New, slow growth laws appear in the context, where there exist both straight stacking faults and curved soliton domain walls. The models contain several annealable pinning centers, which slow down the growth.