Mechanical properties and electrical conductivity of oriented-SiC-whisker-reinforced Al2O3/Cu composites

Oriented SiC whisker-reinforced Al2O3/Cu composites were fabricated by powder metallurgy and hot extrusion. The microstructure of the composites was characterized by scanning electron microscopy. The mechanical properties and electrical conductivity of the composites were measured. The results indicated that the SiC whiskers aligned along the extrusion direction, and the nano Al2O3 particles were uniformly dispersed in the Cu matrix with ideal interfacial bonding. Particle and whisker hybrid reinforcement significantly enhanced the mechanical properties. The yield strength and elongation of (1 vol.%SiCw + Al2O3)/Cu composites were 6% and 15.6% higher than those of the Al2O3/Cu composites, respectively. The experimental yield strength was consistent with the theoretical value associated with different strengthening mechanisms. The main strengthening mechanisms were fine grain strengthening, Orowan strengthening and load transfer strengthening. The electrical conductivity of all the composites was higher than 82.8% IACS; however, the SiC whiskers led to electrical conductivity anisotropy. In general, the electrical conductivity of composites is related to the volume fraction and type of reinforcement. Therefore, the influence of the hybrid composition on the electrical conductivity was studied, and an analytical model for the electrical conductivity of hybrid-reinforced copper matrix composites was established, including the characteristic parameters of the particles and whiskers. The model and presented findings can provide a design basis for hybrid-reinforced composites.