An Investigation of Parameters Involved and Defects in the Fabrication of Al–SiC Nanocomposite Using Hot Extrusion Technique

Abstract

In the present work, some parameters including temperature, pressure, boundary conditions (lubricant and friction), and also defects during hot extrusion technique (HET) of specimens were studied and their reasons were analyzed. The nanocomposite powders were prepared by a powder metallurgy route consisting of mechanical milling, cold pressing, and HET. Micron-sized Al with different amounts of SiC nanoparticles, 0, 1.5, and 3 vol%, were used to fabricate the specimens. The physical and mechanical properties of the extruded samples such as density, microhardness, tensile strength, and also the microstructure of the materials were evaluated. It was found that by increasing the nanoparticle contents, microhardness and tensile strength increased and ductility declined. The right and appropriate design of die, using foil or aluminum cans, proper lubricant, and extrusion rate were important parameters to be controlled to obtain minimum defects. The results showed that the temperature of 550 °C was more appropriate towards achieving superior tensile strength than at 500 °C and better surface finish than at 500 and/or 600 °C.