Magnetostriction of Aluminum-Iron Single Crystals in the Region of 6 to 30 Atomic Percent Aluminum

The spontaneous saturation magnetostriction and the forced magnetostriction were measured on slowly cooled single crystals of the ferromagnetic aluminum-iron alloys in the composition range from 6 to 30 atomic percent aluminum. The value of the first constant of spontaneous saturation magnetostriction at 6 atomic percent aluminum is similar to that at 6 atomic percent silicon in iron. At compositions containing larger amounts of aluminum, the first constant becomes very large; however, near 30% aluminum the constant drops and approaches zero. The second constant of spontaneous saturation magnetrostriction is negative below 17% aluminum, reaches a maximum near Fe3Al, and drops near 30% aluminum. Values of the isotropic forced-magnetostriction constant below 25 atomic percent aluminum were found to be slightly higher than that for iron but less than that for silicon iron. Above 25% aluminum the isotropic constant became very large. The anisotropic forced-magnetostriction constants were the largest for the single crystal having 29.6% aluminum; a good fit of the experimental data to the calculated curve was found for this alloy.