Study Of The Microstructure And Properties Of The Low Concentration Of Cu-ni-si Alloy

Cu-1.50Ni-0.34Si and Cu-1.50Ni-0.34Si-0.05Mg-0.03P-0.2Zn alloys have been prepared using medium frequency induction furnace. The micro-hardness and electrical conductivity of two alloys under different heat treatment conditions were measured, and the microstructure of alloy was examined by using Optical Microscopy (OM) and Transmission Electron Microscopy (TEM). The main conclusion remarks are as follow:1. The best uniform heat treatment for Cu-1.50Ni-0.34Si alloy is 900℃for 2h, the best solution quenching treatment is 800℃for 1h. After 8h aging at 450℃, the micro-hardness and related electrical conductivity of the solid solution alloy can be 175HV and 53%IACS。2. The research obtained the process technology of Cu-1.50Ni-0.34Si alloy:hot rolling and on-line quenching. Under the condition of final rolling at 650℃, its combination properties after aging can be equivalent to quenching after solution at 800℃.3. Higher the aging temperature is, shorter the time need for Cu-1.50Ni-0.34Si and Cu-1.50Ni-0.34Si-0.05Mg-0.03P-0.2Zn alloy to achieve hardness peak value and lower the peak value, while higher the electric conductivity will be. The best aging temperature for both alloys are 450℃, since the alloys present high hardness and excellent electric conductivity in a wide range of time.4. With the increases of cold deformation, the peak hardness will increase and the Cu-1.50Ni-0.34Si alloy can easily be over aging. Small amount of P-Mg-Zn addition can significantly increase the strength, decrease the electrical conductivity and delay the overaging time of the alloy.5. Double cold rolling and double aging treatment can accelerate aging process of alloy, but cannot improve the combination properties of Cu-1.50Ni-0.34Si. While the micro-hardness and related electrical conductivity of Cu-1.50Ni-0.34Si-0.05 Mg-0.03P-0.2Zn alloy can be improved to 220HV and 45%IACS by adopting 40% cold rolling+ pre-aging 16h at 450℃+80%cold rolling+15min aging at 450℃.6. During aging, precipitated phase of Cu-1.50Ni-0.34Si alloy is plated 8-Ni2Si. In the early stage,δ-Ni2Si particles coherent with matrix. As the aging prolonged, the particles grow and become incoherent. The oriental relationship between matrix andδ-Ni2Si precipitates was that: (001)m//(100)ppt, [110]m//[001]ppt, the habit plane being{110}m.7. Activation energy of Cu-1.50Ni-0.34Si and Cu-1.50Ni-0.34Si-0.05Mg-0.03P-0.2Zn alloy which went through quenching after hot rolling is 64.90kJ/mol and 81.42 kJ/mol. Addition of Mg-P-Zn increases the activation energy and delays the aging process of Cu-1.50Ni-0.34Si alloys.