Correlation of thermal models with microstructural effects in continuous MMC wire production

A recently developed continuous pressure infiltration process at Northeaste rn University has successfully produced completely infiltrated metal matrix composite (MMC) wires showing high mechanical strength. Thermal models are developed for two key regions (the entrance and middle orifices) of the hi gh-pressure infiltration apparatus to identify heat transfer conditions tha t relate to process limitations and resulting MMC microstructure. For compo sites composed of 2024-aluminum alloy with alumina fiber reinforcement, exp erimental measurement of resulting grain size and solute segregation are co mpared for two processing velocities. At lower pulling velocity, the overal l average matrix grain diameter (3.92 mu m) is larger than that measured at higher pulling velocity (1.84 mu m). Segregation is notably higher at lowe r pulling velocities. Predictions from thermal models correlate with micros tructural observations, and are utilized to determine a maximum processing velocity for improved process control. (C) 1999 Elsevier Science S.A. All r ights reserved.