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New Results on the Iron-Nickel Equilibrium Diagram-The Gamma/Gamma-Plus-Alpha Boundary
Published online by Cambridge University Press: 06 March 2019
Abstract
Solid state equilibria in iron-nickel alloys containing 0-65 at % nickel were studied by X-ray diffraction techniques, and the gamma/gamma + alpha boundary has been relocated.
Alloys were prepared by thermal decomposition and hydrogen reduction of mixed-crystal iron—nickel formates and by distilling off mercury from mixed ironnickel “amalgams,” both methods of preparation yielding equilibrium alloys in relatively short time at temperatures below 500°C, Alloys were studied at various temperatures by use of a high-temperature diffraction camera, or at room temperature as quenched from the temperature of preparation.
The study showed that the gamma/gamma + alpha boundary lies at generally higher temperatures than in previous diagrams and is concave downwards instead of upwards. The boundary shows three discontinuities which have been located to lie at approximately (a) 3 at % nickel and 760°C, (b) 35–43 at % nickel and S25°C, and (c) 50 at % nickel and 330°C. These discontinuities indicate the possible existence of three isobaric invariant three-phase equilibria, heretofore, undetected in the iron-nickel system. Further studies covering the entire range of iron—nickel alloy compositions are in progress.
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- Copyright © International Centre for Diffraction Data 1966
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