Production and properties of Co-based metallic-glass-reinforced aluminum matrix composites

Abstract

Cobalt (Co)-based metallic-glass-particulate-reinforced aluminum (Al) matrix composites were prepared by microwave sintering under air atmosphere conditions at a proper temperature that avoids crystallization of reinforcing particles. Composite powders containing 5–20 vol.% metallic-glass reinforcements were prepared by using a high-speed vibrating ball mill, and green compacts were sintered through the microwave-heating method at 500°C for 30 min. Microstructural features were investigated by X-ray diffraction and scanning electron microscopy. Furthermore, the mechanical properties of the samples were evaluated through compression tests and Vickers hardness measurements. Sintering studies showed that the metallic-glass particles interacted with the microwaves during the microwave-heating process over a certain temperature (>500°C) apart from the susceptor heating element and caused excessive heating, which led to overheating of the composite sample in an uncontrollable manner. Therefore, the sintering temperature of the samples was selected to be 500°C. Investigations of the microstructure of the samples with well-distributed reinforcements revealed that there was no brittle intermetallic phase formation between the reinforcement and matrix interfaces. The results showed that the composite samples milled for 2 h exhibited significantly higher compressive strength and hardness values compared with pure aluminum.