A Review of the Modelling of Semi-Solid Processing from an Experimentalist’s Point of View

Semi-solid processing of metallic alloys and composites utilises the thixotropic behaviour of materials with non-dendritic microstructure in the semi-solid state. Modelling of die fill leads to more effective die design to avoid defects. Here approaches to modelling are summarised. They can be categorised as one phase or two phase and as finite difference or finite element. Although many workers have qualitatively compared their predictions with experimental results (usually obtained through interrupted filling), there is little quantitative data. There are no direct comparisons of the capabilities of various software packages to model die fill accurately. In addition, the modelling depends on rheological data. This is sparse, particularly for the increasingly complex two-phase models. Direct flow visualisation can provide useful insight and avoid the effects of inertia in interrupted filling experiments.