An isothermal section of the Mg-Nd-Gd ternary system at 723 K was established by diffusion triple technique and electron probe microanalysis （EPMA）. Mg3Gd and Mg3Nd form a continuous solid solution （Gd,Nd）3Mg, and a continuous solid solution （Gd,Nd）Mg is also formed between MgGd and MgNd. Mg7Gd, Mg5Gd, Mg2Gd, Mg41Nd5, （Gd,Nd）3Mg and （Gd,Nd）Mg are found in the ternary system. In these intermetallic phases, Mg7Gd has been reported to be a metastable phase in previous literatures. The solubilities of Mg, Gd and Nd in all the phases were detected. Furthermore, four three-phase equilibria, α（Mg）＋Mg7Gd＋Mg41Nd5, Mg7Gd＋Mg5Gd＋Mg41Nd5, Mg5Gd＋Mg41Nd5＋（Gd,Nd）3Mg and （Gd,Nd）3Mg＋（Gd,Nd）Mg＋Mg2Gd, were identified in the isothermal section.
Based on the available experimental data,the Bi-Ni binary system was optimized thermodynamically by the CALPHAD method.The solution phases,including liquid,fcc_A1（Ni） and rhombohedral_A7（Bi）,were described as substitutional solution phases,of which the excess Gibbs energies were expressed with the Redlich-Kister polynomial.The intermetallic compound,BiNi,was modeled using three sublattices（Bi）（Ni,Va）（Ni,Va） considering its crystal structure（NiAs-type） and the compatibility of thermodynamic database in the multi-component systems,while Bi3Ni was treated as a stoichiometric compound.Finally,a set of self-consistent thermodynamic parameters formulating the Gibbs energies of various phases in this binary system were obtained.The calculated results are in reasonable agreement with the reported experimental data.
