Electrical resistivity of Fe-Rich FePd alloys between 77 and 1250 K

Abstract

Electrical resistivity (ϱ) of FePd alloys containing 0.5, 1.0, 3.0, 7.9, 10.0, and 11.9 at% Pd is studied with increasing and decreasing temperatures (T) between 77 and 1250 K. Special attention is given to anomalies due to the magnetic phase transition, the α–γ transition, and the metastable phase which exists in higher concentration Pd samples. The Curie temperature (TC) is determined from the maximum in the dϱ/dT vs. T curves which rise gently towards a maximum and then drop sharply above this maximum. The α–γ transition exhibits hysteresis in the electrical resistivity. It is found that the temperature region for the a-y transition can be slightly affected by the heating and cooling rates. The metastable phase in higher concentration Pd alloys is observed from an irreversible shift in the electrical resistivity data for FePd samples containing 7.9, 10.0, and 11.9 at% Pd. The experimental results are described from the viewpoint of the metallurgical phase diagram and the electronic structure of the FePd system. The d2ϱ/dT2 analysis suggests that the critical exponent λ+ is practically independent of Pd concentration in Fe-rich FePd system.