Experimental Determination And Thermodynamic Assessments Of Phase Equilibria In Some Co-V Based Alloys

Co-V based alloys are the new potential magnetic materials,due to their excellent magnetic and mechanical properties.In order to improve the alloy properties, optimize alloy compositions and processing,it is necessary to investigate the phase diagrams and thermodynamic data in the Co-V based alloys.In this paper,experimental determination and thermodynamic assessments on the phase equilibria of the Co-X(V,Er),V-X(Er,Ge,Pt) binary systems and Co-V-X(Pt, Ta,B,Er) ternary systems were carried out.Major research contents are listed as follows:(1) The phase equilibria of the Co-rich side in the Co-V binary system and Co-V-Pt ternary system have been experimentally determined by using the optical microscopy (OM),electron probe microanalysis(EPMA),and X-ray diffraction(XRD).(2) The phase equilibria of the ternary Co-V-Ta system at 1300℃,1200℃and 1100℃have been experimentally determined by using the optical microscopy(OM), electron probe microanalysis(EPMA),and X-ray diffraction(XRD).(3) The phase equilibria of the Co-X(V,Er) binary systems have been thermodynamically optimized based on the available experimental data.A set of self-consistent and reasonable thermodynamic parameters is obtained for each binary system,which describes the Gibbs energies of the solution phases and the intermediate phases.(4) The phase equilibria of the V-X(Er,Ge,Pt) binary systems have been thermodynamically optimized based on the available experimental data.A set of self-consistent and reasonable thermodynamic parameters is obtained for each binary system,which describes the Gibbs energies of the solution phases and the intermediate phases.(5) On the basis of experimental data obtained by this work and previous reports, the phase equilibria of the Co-V-X(Pt,Ta,B,Er) ternary systems have been calculated and optimized.The calculated results are in good agreements with the experimental data.The obtained thermodynamic parameters of each system in this work can be applied to establish the thermodynamic database of Co-V based alloys.In addition, the calculation results in this work can provide important theoretical guidance on designing high properties Co based alloys.