Modeling microporosity in aluminum–silicon alloys: a review

Abstract

Advances in the scientific understanding of porosity development in aluminum alloys have led to the evolution of a number of descriptive models over the past four decades, ranging from analytic solutions to highly complex simulations of evolving porosity and microstructure with stochastic nucleation and growth. In this review, published models are categorized according to their approach and include: (i) analytic solutions; (ii) criteria functions; (iii) computational models using Darcy's law; (iv) gas diffusion models; and (v) continuum-stochastic models. The benefits, limitations and effectiveness of each type of model are considered. None of the models reviewed provides accurate predictions over the complete range of conditions found in industrial shape castings, where both shrinkage and gas evolution are major driving forces. An ideal model would incorporate all physical phenomena; however, because of the vast number of material properties and boundary conditions required, an `ideal' model may be too complex to be industrially viable. Therefore, the most productive path for the future development of advanced models is proposed.