Magnetization and Magnetostriction in Terbium–Dysprosium–Iron Alloys

Some results of magnetostriction and magnetization measurements are presented on a small representative sample of four specimens from an original study of over one hundred specimens of the Tb-Dy-Fe alloy which we have measured in recent years. The results of these investigations show a progressive improvement in strain amplitude, Δλ, and strain derivative, dλ/dH, of the material. The highest strain amplitude observed to date is Δy = 2.2 × 10−3 and the highest strain derivative is (dλ/dH)max = 0.312 × 10−6 A−1 m. These improvements result mostly from the reduction of the volume fraction of second phase material and an increase in the fractional occupancy of domains oriented initially at right angles to the unique axis of the cylindrical specimens. The initial domain alignment is a result of thermomagnetic treatment of the finished specimens in which the materials are subjected to a magnetic field normal to the axis of the specimens.