Microstructure and properties of high-strength Cu-Ni-Si-(Ti) alloys

The tradeoff between the strength and the fracture elongation in the high-strength Cu-Ni-Si alloy became a hot research topic recently. Cu-Ni-Si-(Ti) alloys were fabricated in a vacuum induction melting furnace to study the effects of titanium on the microstructure and mechanical properties of Cu-Ni-Si alloys with different thermo-mechanical treatments. After homogenization at 900 degrees C for 4 h, hot-rolled by 80%, solution treatment at 970 degrees C for 2 h, cold-rolled by 50%, and finally aged at 450 degrees C for 180 min, the studied Cu-10Ni-Si-2Ti alloy achieved the hardness of HV 252.4, electrical conductivity of 23.6% IACS, tensile strength of 764.4 MPa, yield strength of 622.26 MPa, fracture elongation of 10.4%, and strength-elongation product of 7.95 GPa%, which are less than those of the studied Cu-10Ni-2Si alloy. The addition of Ti contributed to refining the microstructure, suppressing the decreasing trend in mechanical properties after peak hardening, and arousing a primary substructure strengthening mechanism rather than the precipitation strengthening in Cu-Ni-Si alloys. These findings provide essential understandings of the effects of the Ti on Cu-Ni-Si system alloys, and the designed Cu-Ni-Si alloys with high-strength and fracture elongation could fulfill some requirements of the electronic and electrical industry.