Microstructures and mechanical properties of carbon tubes reinforced AZ91D magnesium matrix composites prepared by squeeze casting

Abstract

Carbon nanotubes reinforced magnesium matrix nanocomposites (CNTs/AZ91D) were fabricated by squeeze casting. Microstructure and mechanical properties of 1.0wt.%CNTs reinforced AZ91D nanocomposites at different squeeze pressures were investigated. The results showed that the grain size of the α-Mg matrix decreased and more eutectic β-Mg17Al12 phase appeared with increasing of squeeze pressure. Squeeze pressure had a great influence on the mechanical properties of CNTs/AZ91D nanocomposites, with 75 MPa of which the composite has the optimal comprehensive as-cast mechanical properties. A remarkable increase in tensile strength and ductility was found for the squeeze cast 1.0wt.%CNT/AZ91D composites after solid solution and aging heat treatment, the ultimate tensile strength, yield strength and elongation of which can reach as high to 242 MPa, 155 MPa and 7.3%, respectively. Furthermore, the fracture behavior of the investigated tensile specimens at squeeze casting and heat treatment conditions are analyzed and discussed.