Improved strength-ductility synergy in a novel CrCoNiFe/Cu composite via metallurgical bonding interfaces

The CrCoNiFe high entropy alloy particle reinforced Cu matrix composites with up to 20 wt% reinforcements were successfully fabricated through rapid electrical current hot-pressed sintering. The results demonstrate that the addition of CrCoNiFe particles into Cu matrix can effectively refine the grain size of Cu matrix and benefits to form a metallurgical bonding interfacial diffusion layer (CrCoNiFeCux), which ultimately improves the strength-ductility synergy of the CrCoNiFe/Cu composites. The relative density increases from 97.3 % to 99.1 %, the microhardness increases from 60.3 HV0.1 to 113.8 HV0.1, the ultimate tensile strength increases from 208 MPa to 335 MPa and the softening temperature improves from 660 degrees C to 730 degrees C but electrical conductivity decreases from 97.8 % to 32.3 % IACS when the CrCoNiFe reinforcement content in the composites increased from 0 to 20 wt%. The as-produced CrCoNiFe/Cu composites possess good ductility with tensile elongations of > 30 %. The strengthening mechanism analysis reveals that the geometrically necessary dislocations strengthening mechanism contribute predominantly to the improvement of yield strength.