Effect of Nano-Cu Particles on the Microstructure and Mechanical Properties of Cu/AZ31 Composites

The trade-off relationship between strength and ductility severely constrains the potential applications of magnesium matrix composites (MMCs). In this work, nano-Cu particle reinforced AZ31 composites achieved simultaneous improvements in strength and ductility. Nano-Cu/AZ31 composites were prepared using a powder metallurgy method combined with hot extrusion. The results showed that the addition of nano-Cu particles refined the grains of the composites, increasing the probability of activation of the pyramidal slip system. The evolution of tiny secondary phases from Cu particles inhibited the dynamic recrystallization (DRX) behavior of the composites. The as-extruded 1 wt% Cu/AZ31 composites exhibited the best mechanical properties, with yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) reaching 223 MPa, 309 MPa, and 13.7%, respectively, representing enhancements of 21.9%, 11.2%, and 83% compared to the AZ31 matrix. The increase in strength originated from grain refinement, mismatch in thermal expansion coefficients, and Orowan strengthening, while the enhancement in ductility was attributed to the initiation of more slip systems and the synergistic effect of nano-Cu particles.