The Effects of Extrusion Ratio on Microstructure and Mechanical Properties of Hybrid Micron SiC and Carbon Nanotube Reinforced AZ61 Composite

Abstract

A hybrid micron SiC and carbon nanotube (CNT) reinforced AZ61 composite is fabricated by powder metallurgy method and then extruded at different extrusion ratios (λ = 16, 36, and 56, respectively) at 350 °C. The effects of the extrusion ratio on the microstructural evolution and mechanical properties are studied systematically. The results reveal that both the porosity and average grain size of the composite reduce with extrusion and with an increase in the extrusion ratio. The basal texture of the composite is formed during hot extrusion and further enhanced with the increase in the extrusion ratio. These changes in microstructural features lead to an effective enhancement of the overall mechanical properties. Particular emphasis is placed on interrelating the effects of the porosity with the strength of the composites. In addition, an empirical expression is successfully proposed to describe the relationship between the porosity and the strength.