PHASE RELATIONS IN NIOBIUM-GALLIUM SYSTEM

Niobium-gallium alloys and diffusion couples were studied in the composition range 0-70 wt.% Ga by metallography, thermal analysis, electron microprobe, and X-ray diffraction. Five intermetallic compounds were identified; their tentative formulae, modes of formation, and melting or decomposition temperatures are as follows: 1. (A) Nb3Ga peritectic 1900 ° ± 20 °C 2. (B) Nb3Ga2 congruent about 1800 °C 3. (C) NbGa peritectic 1490 ° ± 20 °C 4. (D) Nb2Ga3 peritectic 1280 ° ± 10 °C 5. (E) NbGa3 peritectic 1240 ° ± 10 °C. A eutectic reaction occurs between the first two compounds at 1750 ° ± 25 °C and 25 wt.% Ga. The solubility of Ga in Nb decreases from 12 wt.% at 1900 °C to about 7 wt.% at 1600 °C. © 1968.