Experimental Investigation of Phase Equilibria in the Nb-V-Hf Ternary System

In this study, the phase equilibria of the Nb-V-Hf ternary system at 1300, 1100 and 1000 °C were experimentally investigated by means of back-scattered electron imaging, electron probe microanalysis, and x-ray diffraction. The results show that one ternary Laves compound with a hexagonal C14 structure is found in the isothermal sections that were studied. The bcc phase forms a large continuous solid solution, and no phase separation occurs at 1000 °C as had been claimed in the literature. As the temperature rises from 1000 to 1300 °C, the bcc structure can be observed in the Hf-V side, and the phase region of C15 reduces.