Enhancing ductility of AL6061 + 10 wt.% B4C through equal-channel angular extrusion processing

Additions of high modulus particles to aluminum alloys offer the potential to develop a high stiffness, lightweight composite. Powder metallurgy was used to create a metal matrix composite of aluminum alloy 6061 and 10 wt.% boron carbide particles. Characterization of the as-fabricated material showed the presence of agglomerates of B4C particles and some residual porosity. Evaluation of the mechanical properties showed little improvement to the elastic modulus, low tensile strength and no significant amount of ductility. The material was processed by equal-channel angular extrusion (ECAE) using a variety of parameters, e.g., temperature, number of passes through the die, route, intermediate anneal, etc. Subsequent microstructural characterization revealed a redistribution of the B4C particles. ECAE processing also eliminated residual porosity and improved the elastic modulus as well as other mechanical properties. The biggest improvement was observed in the elongation to fracture which increased to >10%.