Effect of continuous extrusion forming on mechanical properties of aged Cu-Ni-Si alloy

Cu -Ni -Si alloy is extensively utilized as the main material for lead frames, and its preparation process and mechanical properties are closely related. In this work, two processing routes were employed to prepare Cu-1.8Ni0.45Si alloys. One (named traditional processing, TP) involves vacuum casting followed by hot rolling, while the other (named short processing, SP) involves downward continuous casting and CONFORM. The variation trend and mechanism of its tensile strength and elongation were analyzed by SEM, EBSD and TEM. The results showed that the tensile properties of Cu-1.8Ni-0.45Si alloy were greatly improved after CONFORM treatment. CONFORM enables Cu-1.8Ni-0.45Si alloy to facilitates enhanced internal deformation energy storage and grain boundary density in the matrix after cold deformation, making it easier for the aging process to further precipitate and grow Ni 2 Si phase. Compared with TP, the tensile strength of the alloy decreases slightly, but the elongation increases significantly.