Abstract
An isothermal section of the Co-Nb-Ni system was studied at 1200 ‡C with alloys annealed for 288 h (12 days) using XRD and metallography. Phase boundaries of several phase regions were determined through elemental analysis of phases in equilibrium using a scanning electron microscope. Niobium solubility in fcc Co-Ni alloys was found to be ~9 at. % Nb. Alarge extension of the Co2Nb phase region (from ~21 at.% Nb to ~36 at.% Nb and up to ~55 at. % Ni) was found. A continuous series of solid solutions exists for the Μ phase. The Μ-phase region appears to be narrow, ~6 at.% Nb wide. The NbNi3 and Co3Nb phase boundaries were not determined, but there are indications that they extend from the binaries by about 15 at. % Co and 10 at. % Ni, respectively. Existence of a phase or phases at~67 at.% Nb was detected. However, inconsistency of phase relations indicates that these phases may arise due to inability to attain proper phase equilibrium at this high Nb content.
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Gupta, K.P. The cobalt-niobium-nickel system. JPE 18, 419–425 (1997). https://doi.org/10.1007/BF02647697
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DOI: https://doi.org/10.1007/BF02647697