Effect of the Order‐Disorder Transition on the Electrical and Magnetic Properties of $Fe3Al$

Over a range of compositions in the vicinity of the composition, $Fe3Al$⁠, the Fe–Al system undergoes an order‐disorder transition (at $T = To$⁠) which is of second order. This is followed by a ferromagnetic transition at a lower temperature. We have measured both the electrical resistivity and magnetic susceptibility in a large temperature interval which embraces both transitions. An anomaly occurs in the electrical resistivity in the vicinity of the order‐disorder transition which has the general character of the anomaly predicted for an ideal localized antiferromagnet. The anomaly is characterized by a monotonically decreasing resistivity with increasing temperature in the vicinity of $To$ and a divergence in the temperature derivative of the resistivity at $To$⁠, and can be explained as arising from a combination of superzone‐induced gap effects and concentration fluctuations. An anomaly is observed in the magnetic susceptibility in the vicinity of $To$ which reflects a changing spin‐spin exchange interaction in the vicinity of $To$⁠.