Experimental investigation of phase equilibria in the Co–W–Nb ternary system

The phase equilibria in the Co–W–Nb ternary system were experimentally investigated using optical microscopy, electron probe microanalysis and X-ray diffraction on equilibrated alloys. In this study, isothermal sections of the Co–W–Nb ternary system at 1000 °C, 1100 °C and 1200 °C were determined, and no ternary compound was found. Further results show that a Nb-stabilized Co3W phase is stable at 1100 °C, but not at 1200 °C in the Co–W–Nb system. The α Co2Nb and γ Co2Nb phases were identified to possess large solubility of W in the present study. The newly determined phase equilibria of the Co–W–Nb in the present study will provide useful information for the development of cemented carbides and high-temperature structural materials.