Effect of Composition and Processing on the Activity of Some Magnetostrictive Materials

The dynamic magnetostrictive properties of a number of magnetic materials were determined as a function of composition and processing. The materials investigated include nickel, 2V‐Permendur, a cobalt‐nickel alloy, several Ni‐Fe and Al‐Fe alloys, and a group of ferrites represented by the formula Ni1−x−yCoxFe2+yO4 with 0.00≤x≤0.04 and 0.00≤y≤0.08. The parameters measured were: electromechanical coupling coefficient k, reversible permeability μr, dynamic magnetostrictive constant λ, Young's modulus E, and stress sensitivity λμr.The stress sensitivity of both the Al‐Fe alloys and the cobalt‐substituted nickel ferrous‐ferrites is sensitive to cooling rate. Ordered Al‐Fe samples containing approximately 12.0% aluminum were more stress sensitive by a factor of six than were disordered samples of the same compositions. Disordering was accomplished by quenching from above the ordering temperature (approximately 600°C). When 6% of the nickel in cobalt‐substituted nickel ferrite was replaced by divalent iron, the ...