On the Interaction Energy of Interstitial Atoms and Solute Atom Pairs with the Magnetization

Abstract

A method has been devised to determine the magnitude and sign of the interaction energy with the magnetization of interstitial atoms and solute atom pairs in iron. By applying a uniaxial stress to the specimen, a known amount of interstitials or solute atom pairs can be distributed over a given class of sites, and the magnetic anisotropy energy induced in this way is compared with the one obtained by conventional annealing under magnetic field in the absence of stress. The induced anisotropy energies are measured either from the magnetization curve or by means of a magnetic-torque magnetometer. The data obtained for C in α-iron show that the magnetic interaction energy is positive, i.e., the tetragonally distorted cells occupied by the interstitials tend to have their tetragonal axis aligned at right angle with the magnetization, thus confirming a previous result of De Vries et al. obtained from magnetostriction aftereffect. Some preliminary results are also given for aluminum solute atom pairs in a Fe-Al alloy.