Effect of Mg on microstructure and properties of Cu-Ni-Fe-P alloy with high strength and high conductivity

The effect of Mg element on microstructure, strength, conductivity and softening temperature of the Cu-Ni-Fe-P alloy was investigated in details by TEM, EBSD and XRD. The results showed that Cu-0.3Ni-0.3Fe-0.16 P-0.1Mg alloy with high strength and high conductivity was obtained. The tensile strength, microhardness and electrical conductivity of the Cu-Ni-Fe-P-Mg alloy were 692 MPa, 215 HV and 65.2 %IACS, respectively by 90% coldrolling(90 %CR) + aging at 450 degrees C for 4 h + 60 %CR. The microstructure analysis indicated Mg element refined the size of grains and (Ni, Fe)2P precipitation phase thus improving the strength of Cu-Ni-Fe-P alloy. The strengthening contributions for Cu-Ni-Fe-P(-Mg) alloys were mainly the precipitation strengthening and dislocation strengthening. In addition, the Cu-Ni-Fe-P-Mg alloy had an excellent softening temperature, as the Mg element delayed the recrystallization of deformed structures because of inhibiting the coarsening of precipitates.