Study On Aging And Thermal Deformation Behavior Of CuNiSi Series Alloys

With the high competitive performance and widely application prospect, CuNiSi alloys being excellent candidates for lead frame materials used in large-scale integrated circuit.In this paper, the effects of cold deformation, aging temperature, and aging time on the structure and properties of CuNiSi alloy with trace alloy elements were studied. The results showed that the integration performance can be improved by combination cold deformation and aging. For example, the microhardness and electrical conductivity of CuNiSi alloy were 172HV and 28%IACS respectively when it was aged at 500℃for 0.5h. And the microhardness and electrical conductivity of CuNiSi alloy achieved 229HV and 32%IACS respectively when it was aged at 500℃for 0.5h after deforming for 60%. Besides, the effects of microelement P, Ag on the properties of CuNiSi alloy were also researched. The results showed that P can enhance the microhardness of CuNiSi effectively, but the electrical conductivity increase slightly, and Ag can increase the microhardness of CuNiSi, but the effect of Ag doesn't as clear as P, moreover Ag can improve the electrical conductivity of CuNiSi. Besides, two stages aging was researched, the research indicated two stages aging can enhance the integration performance of alloy obviously. For instance, The CuNiSi allloy's tensile strength, electrical conductivity and soften temperature have respectively achieved 724MPa,50%IACS and 455℃after 40%+450℃+40%+420℃.The transformation of CuNiSi series alloys aged in different range time was investigated used transmission electron microscope (TEM). It can be found that there was a common phase precipitated Ni2Si in CuNiSi series alloys, and there wasn't other phase besides Ni2Si in CuNiSiAg alloy, but it had Ni3P phase except Ni2Si phase for CuNiSiP alloy.The flow stress behavior of CuNiSiP and CuNiSiAg alloy during thermal compression deformation was studied by isothermal compression test at Gleeble- 1500D thermal-mechanical simulator. The results showed that the dynamic recrystallization was controlled by strain rate and deforming temperature. The higher the temperature, the quicker dynamic recrystallization, and the less strain rate, the quicker dynamic recrystallization, too. The microstructure was strongly depended on the deformation temperature and deformation velocity. The thermal deformation activation energy of CuNiSiP and CuNiSiAg alloys (QCuNiSiP=485.6KJmol-1, QCuNiSiAg=312.3KJmol-1) was counted by Arrhenius hyperbolic sine function, flow stress equation and dynamic recrystallization grain size model of CuNiSiP and CuNiSiAg alloys were established.