Physics of microporosity formation in casting alloys - sensitivity analysis for Al-Si alloys

The problem of microporosity (microshrinkage) formation in casting alloys continues to be of interest in spite of the many computational models proposed. This is because of the complexity of the problem that involves many material and process variables intertwined in complex physics. This paper introduces two models for the growth of a gas pore in the mushy zone of a solidifying alloy. While the models ignore important contributors to the problem, such as fluid transport and stress, they capture the physics that connects the main variables of the process: initial gas content, temperature/fraction solid, cooling rate, temperature gradient, applied pressure and melt purity (pore nucleation). The models have been used to conduct a sensitivity analysis of the process for the particular case of Al-Si alloys.