An X-ray analysis of the nickel-aluminium system

Source abstract

Abstract An X-ray analysis of the nickel-aluminium system has been made. A comprehensive series of powder photographs were taken of slowly cooled alloys, and in addition some quenching experiments were made on the nickel-rich alloys. In several important particulars the results differ from the phase-equilibrium diagram published by Gwyer (1908) (fig. 1a). This diagram has therefore been modified in the direction indicated by our work (fig. 1b). The solid solution of aluminium in nickel shown by Gwyer has been found to contain a miscibility gap at room temperatures. The α-phase, which is a face-centred cubic solid solution of aluminium in nickel, extends to 89 atomic % of nickel at room temperatures. The α'-phase, which is a facecentred cubic solid solution closely corresponding to the composition Ni3Al, has a superlattice (Westgren and Ekman 1930), nickel atoms occupying centres of cube faces and aluminium atoms cube corners. Quenching extends the range of the α-phase until in alloys quenched from 1100° there is no break between the α and α' structures.