Microstructure control of particle reinforced metal matrix composites fabricated by low-pressure infiltration process

Abstract

Process parameters to control the microstructure of particle reinforced MMC in the low pressure infiltration process (LPI process), have been investigated. The mixed powder of reinforcement particle and pure aluminum particle in various volume fraction was employed to control the volume fraction of the reinforcement particles in PRMMC. The Al-12 mass%Cu alloy melt was forced to infiltrate into the mixed powder layer by applying a certain pressure of argon gas on the melt surface. The pressure required to infiltrate remarkably increased from 0.05 to 0.5 MPa with a decrease in the particle size from 100 to 20 μm, indicating that the pressure at the advancing melt surface decreased due to the resistance based on a capillary force and a friction force between melt and particle. In the microstructure of PRMMC obtained, the reinforcement particles were homogeneously distributed and a linear relationship was obtained between the volume fraction of reinforcement particle in the mixedowder and the observed area fraction. It was found that a homogeneous particle distribution and accurate control of the volume fraction of reinforcement particles could be attained in the LPI process.