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 properties of a disordered FePd alloy. Samples with a nominal composition of Fe21Pd79 were produced from 99.99% Fe ingot and 99.95% Pd ingots by melting in an induction furnace in an Ar atmosphere. The disordered γ phase is obtained at room temperature by quenching in ice water from 1273 K. The stability of the disordered phase and its evolution during thermal treatments have been investigated by X-ray diffractometry. The presence of the order phase has not been detected. However, differential thermal analysis measurements indicate the existence of a thermally activated process at around 673 K that could be associated with the annihilation of the quenched-in vacancies. These atomic rearrangements also cause detectable changes in the macroscopic magnetic properties, i.e. increases in the Curie temperature of the alloy and the saturation magnetisation.