Enhanced Micromechanical Modelling of Martensitic Phase-Transitions Considering Plastic Deformations

Abstract
The purpose of this contribution is the presentation of a micromechanical model for martensitic phase transformations which can be applied to a wide range of materials like shape memory alloys (SMA), TRIP-steels (TRansformation Induced Plasticity) and piezoceramics. One of the key-features of the model is the consideration of several martensitic variants in addition to the parent phase austenite based on crystallographic theories. According to a specifically chosen microstructure, a fluctuation field is superimposed to the local, homogeneous deformations. These fluctuations implicate several additional internal variables which are partially supposed to minimize the microscopic energy density. Furthermore, the variables assumed to be ’dissipative’, like the volume fractions of martensite, are determined by evolution laws. Another focal point of our work is the combination of martensitic phase transformations and plasticity. As a first step towards a complete micromechanical description of this problem, we make use of a phenomenological approach for plasticity here. The results of our computations reveal significant differences of the single-crystalline behavior to the well-known macroscopic material response, which is indeed verified by experimental studies.