Effects of microelements on the microstructure evolution and properties of ultrahigh strength Cu–Ti alloys

Modern electronics components require copper alloys to have higher strength and ductility for processing and forming. Cu–Ti alloys exhibit excellent mechanical properties while their plasticity is limited. In this work, high ductility Cu–Ti alloys were fabricated and investigated systematically, results indicated that the samples' strength and plasticity can be improved by adding high Ti and Cr content. The crystal relationship between the β′-Cu4Ti and Cu is that: [100] Cu//[011] β'-Cu4Ti, (020) Cu//(21‾1) β'-Cu4Ti. Further increase aging time, metastable β′-Cu4Ti particles started cellular reaction to be β-Cu3Ti phase, which were detected at the grain boundary. The crystal relationship between the β-Cu3Ti and Cu is that: [100] Cu//[011] β-Cu3Ti, (220) Cu//(400) β-Cu3Ti. The hardness, yield strength, elongation of the CuTiCrMg alloy after aging at 450°C for 30 min are 394 HV, 1057 MPa, and 1.6%, respectively. While, those of the CuTiCrMg–Fe alloy are 370 HV, 1160 MPa, and 10%, respectively. The precipitation strengthening is the primary strengthening mechanism. These findings are of great significance for developing Cu–Ti alloys with high strength and high plasticity.