Relationship and mechanism between microstructure and property of C70250 copper alloy strip prepared by temperature controlled mold continuous casting

Temperature controlled mold continuous casting (TCMCC) technology was used to fabricate the C70250 copper alloy strips. The influences of solidification microstructure on mechanical and electrical properties of C70250 copper alloys were systematically studied, and the relevant influencing mechanism was discussed. The results show that the microstructure of TCMCC C70250 copper alloy has a large number of fine dispersed Ni2Si phases, small angle grain boundaries and columnar grains with strong [001] orientation. The tensile strength, elongation and electrical conductivity of the C70250 copper alloy are 328 MPa, 40.4% and 24.3% IACS, respectively, which are obviously higher than the properties of the C70250 copper alloys prepared by conventional cold mold casting methods. The tensile strength of TCMCC C70250 copper alloy strip significantly increases due to the dislocation plugging inside the grains, which caused by strong pinning effect of Ni2Si phases during room temperature tensile. Straight small angle grain boundaries and columnar grains with strong [001] orientation significantly reduce the hindering effect of grain boundaries on dislocations. The deformation between and within grains is more uniform, and it is not easy to form high strain concentration, which leads to the increase of plastic deformation ability. The scattering effects of solute atoms and transverse grain boundaries on electrons are significantly reduced due to the precipitated Ni, Si atoms and the high orientation of columnar grain structure, which contributes to the improvement of the electrical conductivity.