The present study is to determine the Frank-Kasper phases in the Co-Nb-Ni system. Frank-Kasper phases, also called topological close packed ... Show moreThe present study is to determine the Frank-Kasper phases in the Co-Nb-Ni system. Frank-Kasper phases, also called topological close packed (TCP) phases are one of the largest groups of intermetallic compounds. They are classified into several phases: A15, Laves, σ, µ and the M, P, R phases. In the 1200°C-isothermal section of the Co-Nb-Ni system, the µ phase and Laves phases exist over large composition ranges. In this study, the Co-Nb-Ni ternary system was investigated using optical microscopy(OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and differential scanning calorimetry (DSC). The experimental results were compared with literature data and thermodynamic calculations. XRD was used to identify the Frank-Kasper phases. In comparison with previous investigations, the large extensition of µ phase in the Co-Nb-Ni system was verified. In addition, the small phase (~67at. % Nb) shown in the alloys with ~50at. % Nb is the unstablized impurity phase. On the other hand, according to the results of experiments and thermo-calc, C15 phase was found instead of C14 phase compared with Gupta's study. Show less
The present study is to determine the Frank-Kasper phases in the Co-Nb-Ni system. Frank-Kasper phases, also called topological close packed ... Show moreThe present study is to determine the Frank-Kasper phases in the Co-Nb-Ni system. Frank-Kasper phases, also called topological close packed (TCP) phases are one of the largest groups of intermetallic compounds. They are classified into several phases: A15, Laves, σ, µ and the M, P, R phases. In the 1200°C-isothermal section of the Co-Nb-Ni system, the µ phase and Laves phases exist over large composition ranges. In this study, the Co-Nb-Ni ternary system was investigated using optical microscopy(OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and differential scanning calorimetry (DSC). The experimental results were compared with literature data and thermodynamic calculations. XRD was used to identify the Frank-Kasper phases. In comparison with previous investigations, the large extensition of µ phase in the Co-Nb-Ni system was verified. In addition, the small phase (~67at. % Nb) shown in the alloys with ~50at. % Nb is the unstablized impurity phase. On the other hand, according to the results of experiments and thermo-calc, C15 phase was found instead of C14 phase compared with Gupta's study. Show less
