Simulation of hetero-phase system solidification as in an example AZ91/SiC composite

摘要

A macro model was applied for the simulation of the solidification of composites, based on AZ91 alloy and reinforced by silicon carbide particles. A phenomenon of a composite transition from a liquid to a solid state is, in this model, treated - in simplification - as an equilibrium process. The amount of a solidified composite is a temperature function. However, one should realize, that the volumetric participation of solidified composite is related to a grain nucleation. Due to various kinds of separation surfaces, e.g. casting mould walls, silicon carbide, the heterogeneous nucleation occurs during the composite solidification. Constituents of composites have different thermo physical properties. To simulate solidification process of composite the model in which thermo physical properties are approximated with formulas that permit to calculate them as average from metal matrix and particles properties, is applied. In this model composite is treat as alloy with thermo physical parameters that depends on temperature and volume fraction of SiC particles.