Processing of Al-based MMCs by indirect squeeze infiltration of ceramic preforms on a shot-control high pressure die casting machin

Abstract

The feasibility study on the production of Al-based metal matrix composites via indirect squeeze pressurised liquid metal infiltration of ceramic preforms on a shot-control commercial die casting machine and the related processing optimisation are briefly summarised. It has been demonstrated that under optimised processing conditions high quality composite castings can be repeatably produced. The criteria for the selection of optimal processing parameters are the same as those previously established for direct squeeze casting. That is, preform preheat and melt superheat should be adjusted to preclude premature melt solidification before and during infiltration; infiltration speed should be controlled to avoid permanent deformation of the ceramic preform; the maximum pressure available on the die caster should be deployed to minimise non-infiltration defects; the gating system should be designed to ensure feeding of the solidification shrinkage in the composite casting.