REINFORCEMENT REDISTRIBUTION IN AL-SIC COMPOSITES UNDER CYCLIC DEFORMATIONS

Aluminum-silicon carbide particle composites were subjected to large s train, cyclic deformations at elevated temperatures. The initial micro structure of the composites consisted of distinct elongated clusters o f reinforcements oriented in the extrusion direction. After repeated c ycles where the material was deformed and subsequently returned to its original shape at elevated temperatures, the distribution of particle s throughout the matrix generally became more uniform, although in som e cases small round clusters of reinforcements were observed. Finite e lement calculations suggested that under cyclic deformations, a micros tructure with either a uniform distribution of particles or tight clus ters of particles with a cluster aspect ratio of unity minimizes the s train energy density of the system. The results may provide insight fo r the development of thermo-mechanical processing methods to produce m etal-matrix composites with improved mechanical properties. (C) 1997 A cta Metallurgica Inc.