Thermodynamic Calculation Of Phase Equilibria In The Cu-Mo-X (X: Er, Ni, Si, Th) Ternary System

The Cu-Mo base alloys have widely been used as automotive and electronic materials due to their high thermal and electrical conductivities,low coefficients of thermal expansion,special high-temperature performance,non-magnetic,low gas content,good vacuum and machining properties.In order to improve the alloy properties,optimize alloy compositions and processing,it's necessary to investigate the phase diagrams and thermodynamic properties of the involved systems.In this paper,experimental investigation and thermodynamic calculation were carried out on the phase equilibria of Cu-Mo-X(X:Ni,Si,Th,Er) system as followings:(1) The phase equilibria of the Cu-Mo-Ni ternary system at 1100℃,1200℃and 1300℃and Cu-Mo-Si ternary system at 1100℃and 1200℃have been experimentally determined by using the optical microscope and EDS techniques.(2) The Cu-Th,Mo-Th,Cu-Er and Mo-Er four binary systems and Cu-Mo-X(X:Ni, Si,Th,Er) four ternary systems have been optimized using the CALPHAD method as following:(a) The Cu-Th,Mo-Th,Cu-Er and Mo-Er four binary systems were optimized by using the available experimental information.The calculated phase diagrams and thermodynamic properties agree well with the experimental data.(b) On the basis of experimental phase equilibria data of the ternary systems obtained by this work and lectures,the Cu-Mo-Ni and Cu-Mo-Si ternary systems were assessed and optimized.A set of self-consistent,reasonable and reliable thermodynamic parameters were obtained,which describes the Gibbs free energies of the solution phases and the intermediate phases.The calculated results of Cu-Mo-Ni and Cu-Mo-Si ternary systems are in good agreements with the experimental data.(c) On the basis of the the optimized parameters about Cu-Mo Cu-Th,Mo-Th, Cu-Er and Mo-Er binary systems in this work and literature,a set of Phase diagrams of the Cu-Mo-Th and Cu-Mo-Er ternary systems were extrapolated. The optimized thermodynamic parameters in this work can be applied to build the thermodynamic database of high properties Cu-based alloys.In addition,the calculation results in this work can provide important theoretical guidance on design the Cu-Mo base alloy.