Effect of consolidation parameters and heat treatment on microstructures and mechanical properties of SiCp/2024 Al composites

Abstract

The aim of this paper was to investigate the effect of vacuum hot pressing sintering temperature, sintering time and pressure on the properties of SiCp/2024Al composites. The microstructures and mechanical properties were tested by scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and a mechanical testing machine. The results indicated that increasing hot pressing temperature decreased the number of pores and increased the density and interfacial bonding strength, and improved the mechanical properties of the composites. The composite fabricated at 580°C exhibited the optimum tensile strength, excessive hot pressing temperature easily produced micro-cracks, and the liquid aluminum extrusion and the reduction of Al2 Cu phase. Prolonged sintering times had an adverse effect on the strength of the composite. A hot vacuum pressure needed to be higher than 60 MPa to achieve densification of composites above 99%. Solution treatment plus aging of the composites resulted in a significant improvement in strength and hardness. The higher the sintering temperature, the shorter the time taken to achieve the hardness peak.

Keywords

• mechanical properties
• metal-matrix composites (mmcs)
• powder metallurgy
• sintering
• vacuum hot pressing