Effects of powder ratio and annealing temperature on mechanical properties of Cu/Al composites with core-shell structure

Al-based composites reinforced by Cu particles have been fabricated by powder extrusion method. Effects of Cu content and annealing temperature on the mechanical properties of the composites were studied. The results show that the mechanical properties of the composites are affected by the powder ratio and the diffusion degree between Cu particles and Al matrix, the strengthening mechanism is the synergistic strengthening, which results from the interaction of load transfer, dislocation strengthening and solid solution strengthening. Annealing significantly affects the mechanical strength of the samples with Cu content less than 5 wt%. After annealing at 510 °C for 0.5 h, the tensile strength of 2 wt%Cu and 5 wt%Cu samples increases by 41% and 76%, respectively, compared with that of as-extruded sample. In addition, the annealed samples hold good ductility and the elongations are greater than 15%. However, for samples with Cu content more than 10 wt%, the effect of annealing on the tensile strength seems to be weak, while the plasticity decreases rapidly with an increase of annealing temperature. Suitable powder ratio and annealing temperature can improve mechanical properties of the samples effectively. The tensile strength of 5 wt%Cu sample annealed at 510 °C for 0.5 h is up to 262 MPa, and its elongation is 15.3%.