Virtual dilatometer curves and effective Young’s modulus of a 3D multiphase structure calculated by the phase-field method

The multiphase-field method allows for the calculation of 3D grain structures in multicomponent and multiphase materials. As all geometrical information about the individual grains, their phase properties and their crystallographic orientations are known one can apply these structures directly for virtual testing to calculate e.g. the effective Young’s modulus. The elastic stress and strain fields within the grain structure can be also calculated directly within the multiphase-field framework, especially the internal stresses caused by the transformation strain. In this work we expand our previous phase-field model coupled to linear elasticity by adding external stresses as additional boundary conditions. Using this model we calculate the internal stress and strain distribution, the external volume change caused by phase transformation and the response on external load for a 3D grain structure undergoing the austenite to ferrite transformation, all in the elastic limit. From these calculations we derive a virtual dilatometer curve and the effective Young’s modulus which are useful parameters for e.g. finite element calculations on a larger scale.