The effect of applied pressure on particle-dispersion characteristics and mechanical properties in melt-stirring squeeze-cast SiC p/Al composites

Abstract

The fabrication of metal-matrix composites (MMCs) by casting process is a very promising way of manufacturing near net shape components at relatively low cost. One of these casting processes, the squeeze-casting technique, has characteristics such as fine microstructures as a result of rapid cooling, low porosity and good bonding between the particle and the base alloy. This paper therefore examines, the microstructure and mechanical properties of Al-15%SiC p composite fabricated by the melt-stirring and squeeze-casting method. The correlation between the fabrication conditions and the homogeneous dispersion of particles is investigated for SiC p -reinforced Al composites. The manufacturing parameters in homogeneous mixing are the crucible size, the impeller size, the temperature of the molten metal, the stirring time and the stirring speed in the melt-stirring process. The composite slurry containing SiC p is poured into a pre-heated die, and pressure applied in squeeze casting. The state of dispersion of the reinforcement and the fracture surface are observed by the optical microscope and SEM. The primary product of MMCs billet is prepared under squeeze-casting conditions for applied pressures of 70, 100, and 130 MPa. By assessing observed results systematically, correlation is proposed between the microstructure, the particles behavior, the mechanical properties and the processing parameters for an optimum melt-stirring and squeeze-casting process of MMCs.