Simulating tortuous 3D morphology of microporosity formed during solidification of Al–Si–Cu alloys

A three phase mesoscale model of the formation of microporosity, which solves for solute diffusion limited growth, was extended to multicomponent systems, including eutectic formation. Predictions for binary Al–Cu and Al–Si are compared to ternary Al–Si–Cu system. The three-dimensional morphologies predicted by the mesomodel are compared to X-ray microtomographic observations of as cast microstructures. Owing to the interaction of the pores and the developing solid phases, the microporosity was predicted to have varying degrees of tortuousity as the alloying and processing conditions vary. To enable this comparison to be quantitative, measures of sphericity and tortuousity were developed. A good agreement was found between simulated and experimental results. The effect of changing both composition and solidification parameters is discussed.