Search

The comment (Joubert, 2022) regarding the controversial "NiW" phase detected in our previous study (Tang et al., 2022) was clarified in this work. Our previous conclusion about the presence of the "NiW" phase in the Ni-V-W ternary phase diagram is drawn without considering the contamination of C. In this work, alloys with a composition of Ni 49 V 1 W 50 (at. %) were equilibrated at 1100 and 900 °C and characterized. The result showed that the NiW phase observed in the previous work (Tang et al., 2022) was actually Ni 6 W 6 C carbide, which resulted in misinterpretation of ternary phase constitutions in our previous studies about Ni-V-W (Tang et al., 2022) and Mo-Ni-W (Tang et al., 2020) systems. A new thermodynamic modeling of the Mo-Ni-W ternary system is performed by excluding the presence of "NiW" phase, and this set of parameters can describe the experimental results reasonably. [ABSTRACT FROM AUTHOR]

Phase equilibria in the Ni-V-W ternary system have been experimentally investigated. The phases and their compositions of Ni-V-W alloys annealed at 900 and 1100 °C were studied via X-ray diffraction (XRD) and electron probe micro-analysis (EPMA) measurements. The isothermal section measured at 1100 °C showed a three-phase region of fcc + bcc + (σ). Two three-phase regions [fcc + bcc + (σ) and WNi 4 + WNi + bcc] were detected in the samples annealed at 900 °C. No ternary compounds were detected in the present work. The solubility of V in the Ni-W binary compounds, i.e. WNi 4 , WNi, W 2 Ni, at 900 °C was found to be extremely small (maximum 1.12 at. % V). The solubilities of W in (σ) at 900 and 1100 °C were found to be 2.14 at. % and 3.17 at. %, respectively. The complete isothermal sections at 900 and 1100 °C of the Ni-V-W system were then constructed, which are needed for a thermodynamic optimization of the ternary system. • The isothermal section of the Ni-V-W system at 900 and 1100 °C were established. • The solubility of W in (σ) increases with the increase of temperature. • No ternary compounds were detected in the Ni-V-W system at 900 and 1100 °C. [ABSTRACT FROM AUTHOR]

In this work, the isothermal section at 900 °C, a liquidus projection and invariant reaction temperatures in the Mo–Ni–W ternary system were established using X-ray diffraction (XRD), Differential Scanning calorimeter (DSC) and electron probe micro-analysis (EPMA). Based on the experimental phase diagram data from the present work and the literature, the Mo–Ni–W system was assessed by means of the CALPHAD (CALculation of PHAse Diagrams) method. The liquid, fcc-(Ni), bcc-(Mo) and bcc-(W) phases were described with a regular solution model. The sub-lattice models were used to express Gibbs energies of the intermediate phases of MoNi 3 , MoNi, (Mo, W)Ni 4 , WNi and W 2 Ni. The present modeling covers the entire composition and an extensive temperature ranges of the Mo–Ni–W ternary system, and a set of self-consistent thermodynamic parameters were finally obtained. Comprehensive comparisons between the calculated and measured phase diagram data show that most experimental information is satisfactorily accounted for by the present thermodynamic description. Scheil solidification simulations for a few representative as-cast alloys were performed. It was found that the solidified microstructures can be reasonably described by the Scheil simulation. The liquidus projection and reaction scheme of the Mo–Ni–W system were generated by the presented modeling. [ABSTRACT FROM AUTHOR]

Thermodynamic descriptions of the Al–Co–W, Al–Ni–Ta and Co–Ni–W ternary systems are the foundation for developing thermodynamic database and material design for the Ni-based alloys. In the present work, the Al–Co–W, Al–Ni–Ta and Co–Ni–W systems were optimized based on the reliable experimental data by means of the CALPHAD method. The liquid, γ (Fcc_A1) and β (Bcc_A2) phases were described as substitutional solution model, and the γ' (Fcc_L12), B2 (Bcc_B2), μ (Co 7 W 6) and Ni 3 Ta phases were described with sublattice models. The Co 3 W phase was treated as a stoichiometric compound due to the limited homogeneity range in the Al–Co–W system and described as (Co, Ni) 3 W in the Co–Ni–W system. The self-consistent thermodynamic parameters for the Al–Co–W, Al–Ni–Ta and Co–Ni–W systems were obtained. Comprehensive comparisons between the calculated results and measured phase equilibrium data show that most experimental information is satisfactorily accounted for by the present thermodynamic description. [ABSTRACT FROM AUTHOR]