2019 Volume 60 Issue 4 Pages 611-615
Ternary Nb–Re–Si alloy samples were melted and pulled simultaneously in a tetra-arc furnace and rapidly water-quenched after heat treatment at 1150°C for 1200 h. The microstructures of the samples that had been water-quenched after heat treatment were observed and the Nb, Re and Si concentrations in the constituent phases were measured using an electron probe microanalyzer (EPMA). In the cross-sectional structure of the obtained alloy samples, the lower portion of the pulled part consists of Nb5Si3 and Nb–Re–Si ternary compound phases. By contrast, the upper portion consists of Nb5Si3 and Nb solid solution phases. The Nb solid-solution phase, Nb5Si3 and Nb–Re–Si ternary compound are in equilibrium. It was found that the solubility limit of Si in the Nb solid-solution phase ranges from 0.6 to 1.7 at%, while the solubility limit of Re in the Nb5Si3 phase is 1.3–2.0 at%. The maximum amount of Re in the Nb5Si3 phase in equilibrium with the Nb solid solution is about 0.9 at%.
This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 82 (2018) 409–414.