Synergistic improvement of mechanical properties and electrical conductivity of Cu-Fe alloys by rare earth metals Sc and Y addition

Cu-4.44Fe-0.26Cr-0.4Si-0.29Mg (CFCSM) alloy and Cu-4.73Fe-0.3Cr-0.38Si-0.28Mg-0.2Sc-0.24Y (CFCSM-Re) alloy were designed. After a series of thermos-mechanical treatment, the alloy has excellent overall properties. The CFCSM-Re alloy had an electrical conductivity of 65%IACS, a yield strength of 552 MPa, a tensile strength of 634 MPa and an elongation of 8.12%. The mechanical properties and electrical conductivity of the alloy were improved by the joint addition of Sc and Y. In comparison with the CFCSM alloy, the conductivity, yield strength, and tensile strength of CFCSM-Re alloy have increased by 0.8% IACS, 124 MPa and 116 MPa, respectively. In CFCSM-Re alloy, dual-scale (Fe, Cr)3Si phase and micron scale Cu(Y, Sc) phase were successfully constructed. CFCSM-Re alloys were strengthened by precipitates, which contributed approximately 50% of total strength. Adding Sc and Y inhibited the alloy's softening during annealing treatment, resulting in the alloy having high conductivity, high strength, and high elongation. The combined addition of Y and Sc atoms tended to be distributed in positions including vacancy, dislocation, grain boundary and phase interface. Rare earth metals atoms inhibited the movement of dislocations, rotation of grain boundaries and coarsening of precipitates thus endowing CFCSM-Re alloys with excellent strength, elongation and conductivity.