A three-phase simulation of the effect of microstructural features on semi-solid tensile deformation

A direct finite-element microstructure model for prediction of the deformation behavior of semi-solid metallic alloys is presented. The 2D model geometry is based on a modified Voronoi tessellation. and includes rounded corners to approximate an equiaxed-globular grain structure, liquid surrounding the grains, and micro-porosity. An elasto-plastic empirical constitutive equation is derived for the solid grains. while the liquid is approximated as a perfectly plastic material with a very lose yield stress. The resulting three-phase model was used to investigate the effects of fraction solid. porosity, and grain size on the constitutive behavior of a semi-solid aluminium alloy, AA5182. The model predictions were validated against experimental data at high fraction solid. These simulations reveal a strong correlation between semi-solid grain size and yield stress. and between porosity and strain localization. The application of direct finite-element simulations is shown to be an effective technique for examining the effects of microstructure phenomena on the macro constitutive behavior of semi-solid materials. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.