Effects of vacuum sintering, hip and hp treatments on the microstructure, mechanical and electrical properties of Cr70Cu30 alloys

Abstract

The aim of this paper is to study and produce Cr70Cu30 alloys via vacuum sintering, hot isostatic pressing (HIP) and hot pressing (HP) of powder metallurgy technology. The experimental results show that a lower density of Cr70Cu30 alloys is produced after vacuum sintering, owing to the many pores existing in the sintered Cr70Cu30 alloys, which are not completely removed by HIP treatment. Conversely, the HP treatment of Cr70Cu30 alloys at 1000°C 60MPa for 1 h achieves the optimal density (97.82%), lower apparent porosity (0.65%) and higher international annealed copper standard (IACS) value (22.78%). Moreover, it also obtains the highest hardness (HRB 68.7) and transverse rupture strength (TRS) value (843 MPa). The results indicate that the closed pores can be effectively eliminated and that the mechanical properties of Cr70Cu30 alloys are obviously improved by HP treatment. Meanwhile, the Cr70Cu30 alloys also have an improved microstructure and electrical conductivity. © 2013 The Japan Institute of Light Metals.