Evolution of microstructure and properties of CuCr50 alloy prepared by liquid phase sintering coupled with complementary copper infiltration

CuCr alloy has become the preferred contact material in the field of environmental protection vacuum switches because of its good mechanical and electrical properties, and the development of preparation technology of highly dense and homogeneous CuCr alloy has become one of its research directions. In this paper, the concepts of liquid phase sintering and complementary copper infiltration are coupled to prepare CuCr50 alloys, which are subjected to secondary treatment using solid solution as well as aging heat treatments, to observe the evolution of the microstructure and properties of CuCr50 alloys. It is found that CuCr50 alloy can be prepared stably by liquid phase sintering coupled with complementary copper infiltration. The average particle size of the Cr-rich phase in CuCr50 alloy is 48.9 mu m after liquid phase sintering, solid solution treatment and aging treatment, and the uniformity of the distribution of the Cr-rich phase is improved compared with the billet and sintered state. At this time, the density of the CuCr50 alloy is 7.94 g<middle dot>cm-3, the electrical conductivity is 22.77 MS<middle dot>m-1, and the hardness reaches 113.2 HB. Compared with the requirements in the national standard GB/T 26867-2011, the density, conductivity, and hardness are increased by 0.51%, 42.3%, and 41.5%, respectively. The peak of the density of states at energies around -5 eV on the total density of states diagram is contributed by the superposition of the 3d orbitals of Cu and the 3d orbitals of Cr, which is a reason for the stable existence of the CuCr50 alloy.