Influence of atomic rearrangements on the magnetic properties of a thermally treated disordered Fe21Pd79 alloy

In this work, we present the effect of thermal aging on the magnetic proper ties of a disordered FePd alloy. Samples with a nominal composition of Fe21 Pd79 were produced from 99.99%. Fe ingot and 99.95% Pd ingots by melting in an induction furnace in an Ar atmosphere. The disordered gamma phase is ob tained at room temperature by quenching in ice water from 1273 K. The stabi lity of the disordered phase and its evolution during thermal treatments ha ve been investigated by X-ray diffractometry. The presence of the order pha se has not been detected. However, differential thermal analysis measuremen ts indicate the existence of a thermally activated process at around 673 K that could be associated with the annihilation of the quenched-m vacancies. These atomic rearrangements also cause detectable changes in the macroscop ic magnetic properties, i.e. increases in the Curie temperature of the allo y and the saturation magnetisation. (C) 2001 Elsevier Science B.V. All righ ts reserved.