Study on pore characteristics of irregular and regular particle preforms and their effects on molten aluminum flow

Particle-reinforced aluminum matrix composites (PAMCs) are considered promising materials for electronic packaging, transportation and aerospace. The pore characteristics of preforms are critical factors for performance of PAMCs, yet they have not been comprehensively investigated. In this study, preforms of irregularly and regularly shaped particles with different volume ratios between particles and pore-forming agents were fabricated. Both types of preforms were inspected with a high-resolution three-dimensional X-ray micro-computed tomography (3D μ-CT) scanner. 3D pore network models of preforms were extracted from μ-CT data and the pore characteristics were quantitatively analyzed. Furthermore, the micro-scale infiltration simulations of molten AlSi12 alloys into preforms were conducted. Results indicated that increasing starch content intensified pore formation and particle agglomeration, leading to increasing porosity in both preforms while reducing pore distribution homogeneity. Compared with irregularly shaped particles, the regularly shaped particles reduced spatial separation and promoted more homogeneous pore distribution of preforms. During infiltration, the liquid-phase pressure loss was minimal in the preforms. While at free surface, the liquid-phase pressure was lower, resulting in slower liquid-phase velocity.