The method of using measurements of magnetic saturation intensity of annealed iron-nickel alloys for the determination of the equilibrium phase boundaries, as demonstrated by Pickles & Sucksmith, has been extended. The phase diagram of the system has been determined accurately between 525 and 365° C. The mechanism of phase segregation from the single-phase a-state has been studied, where it was found that contrary to the usual case, one of the phases crystallizes out in its equilibrium

more »

... tion whilst the residue of the alloy progressively and uniformly approaches equilibrium composition. It was possible to study and express quantitatively the rate of attainment of equilibrium, and on evidence obtained in this way the view is based that the lower practical limit of temperature where the equilibrium diagram can be studied by annealing experiments has been reached.