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Interfacial reactions exert crucial effect on the performance of soldering joints. Prediction of the first phase formed at the interface between metals benefit the design of electronic packaging. Based on our previous work, a new scheme is developed in this paper, which aims at predicting phase formation of the interface reaction between metals with the same lattice structure. In the new scheme, the conventional principle considering both the thermodynamic and kinetic factors is employed. A criterion is introduced for the case where a spinodal decomposition exists in the starting solution when the local equilibrium assumption is still valid. Another new criterion involving only nucleation driving force and entropy change is proposed for the case where no spinodal decomposition occurs and the assumption of local equilibrium is no longer valid. The validity of these criteria has been confirmed when applied to predict the intermetallic compound (IMC) formed in the binary diffusion couples such as Al/Cu, Al/Pt, Al/Au, and Co/Zn.

Phase relations of Sn–Cu–Ce system are important in understanding metallurgical role of Ce in Sn–Cu based lead-free solder alloys. Thermodynamic assessment of Sn–Cu–Ce ternary system has been done based on experimental data about phase equilibria and thermodynamic properties by using the CALPHAD approach combined with first-principle calculations of formation enthalpy of key compounds. The solution phases (liquid, Fcc_A1, Bcc_A2 and Bct_A5) were treated as substitutional, of which the excess Gibbs energies were modeled by the Redlich–Kister polynomial. Considering its crystal structure and solid solubility range, intermetallic compound Ce11Sn10 was described with a three-sublattice model (Ce)0.429(Sn)0.429(Ce,Cu,Sn)0.142. Other binary and ternary intermetallic compounds were described as stoichiometric phases because of their limited homogeneity ranges. During optimization, Ce–Sn binary system was first assessed; then phase relations in Sn–Cu–Ce ternary system were modeled by combining with the optimized Ce–Cu and Cu–Sn binary systems in literatures. A set of thermodynamic parameters for all known phases were obtained, which can reproduce most experimental data. The Scheil model was used to simulate the process of non-equilibrium solidification for a series of alloys.

Knowledge of phase equilibria of Fe–Ce–Bi is important for understanding respective effects of rare earth, low melting point elements, e.g. Bi, and the interaction between rare earth and low melting point elements in cast iron. By using a CALPHAD approach, the Ce–Bi binary system was assessed on the basis of reported thermodynamic and phase-equilibrium data and then extrapolated to Fe–Ce–Bi ternary system combined with the Fe–Ce and Fe–Bi binary systems assessed in literatures. Meanwhile, the interfacial reaction between Bi and Fe-45 at%–Ce alloy at 773 K was investigated to verify the reliability of thermodynamic calculations. It was clearly observed that a reaction layer containing CeBi 2 , Fe and liquid (Bi) exists in the couple, indicating the reaction path liquid (Bi)/CeBi 2 +Fe/Fe-45 at%–Ce in this couple. The reaction path was further explained using a recently reported model by adopting the thermodynamics assessed herein.

Phase relations in the Mg–Hg–Ga ternary system have been experimentally and thermodynamically studied. At first, the isothermal sections of the Mg–Hg–Ga system in the Mg-rich region at 673 K and 473 K were investigated by using powder X-ray diffraction (XRD) and scanning electron microscope (SEM) with X-ray energy dispersive spectroscope (EDS). A ternary compound Mg21Ga5Hg3 of tetragonal structure was detected and its homogeneity was determined. Then, based on the experimental literature, a thermodynamic assessment of the Mg–Hg–Ga ternary system was carried out by the CALPHAD approach. Consequently, a self-consistent set of thermodynamic parameters describing this system was obtained, which leads to a good fit between the calculated and experimental data.

Diffusional mobility for fcc phase of the Al–Mg and Al–Mg–Zn systems was critically assessed by using the DICTRA software (Diffusion Controlled Transformation). Good agreement was obtained from comprehensive comparisons between the calculated and experimental diffusion coefficients. The developed mobility database enables reasonable prediction of diffusion and solidification behaviours resulting from interdiffusion, such as concentration profile of diffusion couples and solidification curve of the Al–Mg alloys.

The thermodynamic properties of the Nb-Ti system have been evaluated by using a regular solution model to describe the Gibbs energies of various phases including both equilibrium and metastable phases. A set of thermodynamic parameters more consistent with most of the selected experimental data than previous assessments has been obtained. Stable and metastable phase equilibria, T0 loci, metastable chemical spinodal curve of β phase and thermodynamic properties are calculated with the optimized parameters. With the thermodynamic parameters obtained in this work, authors discuss the possible occurrence range of ω phase.

The Au-Ti binary system has been reassessed using the CALPHAD technique. With the set of optimized parameters a calculated phase diagram, which agrees well with all the experimental information including phase diagram and new thermodynamic data, has been obtained. It is shown that further experimental details are required especially for the liquidus and solidus of βTi at high temperature as well as the transformations between TiAu allotropes