Netted structure of grain boundary phases and its influence on electrical conductivity of Cu–Ni–Si system alloys

Abstract

Cu–Ni–Si alloys with four different Cu contents were fabricated by means of smelting. Subsequently, isothermal aging and hot rolling followed by aging treatment were carried out. The microstructure and phase composition were characterised by optical microscope, transmission electron microscope and X-ray diffractometer. Electrical conductivity was measured by using an eddy current based technique. The results show that the electrical conductivities of as cast Cu–Ni–Si alloys decrease obviously with a decline in Cu content. Isothermal aging is favourable to enhance the electrical conductivities of Cu–Ni–Si alloys with higher than 90Cu content rather than that with <90Cu content containing an integrated netted structure of grain boundary phases. The electrical conductivities of as rolled Cu–Ni–Si alloys can obviously be increased by subsequent aging treatment. The above results suggest that the disintegration of the integrated netted structure at the grain boundary is a promise to achieve high electrical conductivity for Cu–Ni–Si alloys.