Three-dimensional phase field model of proper martensitic transformation

The Phase Field Microelasticity theory is developed for proper multivariant martensitic transformations. The model is based on the exact solution of the elasticity problem in the homogeneous modulus approximation. The model takes into account the transformation-induced coherency strain and provides for the strain compatibility throughout the system. Computer simulations are performed for a dilatationless cubic- --> tetragonal martensitic transformation and for the transformation with parameters corresponding to a martensitic transformation Fe-31%Ni alloy. The development of the martensitic transformation through nucleation, growth and coarsening of orientation variants is simulated at different levels of undercooling. The simulated martensitic structure has a complex polytwinned morphology. Simulation demonstrates that the presence of a non-zero volumetric component in the transformation strain in the Fe-31%Ni system significantly affects the martensitic transformation. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.