SQUEEZE CASTING OF METAL MATRIX COMPOSITES USING SHORT FIBER PREFORMS

Squeeze casting has become one of the accepted liquid metal routes for efficient and effective manufacture of metal matrix composites using ceramic preforms. This acceptance is based on the fact that squeeze casting produces zero porosity castings and the assumption is made that the use of similar casting parameters also produces zero porosity composites. This paper considers the problem of air entrapment during normal squeeze casting operations for fibre perform squeeze infiltration. It is shown that very high pressures are required to eliminate porosity in poorly vented performs, and that oxide and nitride formation can occur in the matrix phase during infiltration and during subsequent periods of heat treatment.