Ni-Cr-N 三元系における 1273K の平衡等温断面図の実験的決定

概要

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An isothermal section of the equilibrium phase diagram in the ternary Ni-Cr-N system was experimentally determined at 1273K. Binary Ni-Cr alloys with chromium concentration from 20 to 79 mass% were nitrided in pure nitrogen gas under various pressures between 10 and 96kPa at 1423 or 1523K. The ternary Ni-Cr-N alloys prepared by the nitriding were equilibrated at 1273K for time varying between 2.0×10^6 and 3.7×10^7s. The concentration of nickel and chromium of each phase in the equilibrated alloys was determined by conventional electron probe microanalysis. Nitrogen in solid solution phases and nitrides was analyzed by a refined method of electron probe microanalysis, which has been recently established by the present authors. A nitride with the metal-atom arrangement of β manganese, which is designated as a π phase, was found to be in equilibrium with a nickel-rich fcc-γ phase, a chromium-rich bcc-α phase, and a di-chromium nitride, which is designated as an ε phase. The chemical compositions of the π and ε phases observed in the present work led to the formulae of Cr_<12>(Ni_<0.94-0.75>Cr_<0.06-0.25>)_8N_<3.9-4.2> and (Cr_<0.99>Ni_<0.1>)_2 N_<0.80-0.97>, respectively. The π phase became unstable above 1473K. This explains a previous unsuccessful attempt to make the Ni-Cr-N ternary π phase by replacing molybdenum in Mo_<12>Ni_8N_4 with chromium.
社団法人日本鉄鋼協会の論文
1991-09-01