Changes in magnetostriction of polycrystalline Tb-Dy-Fe casting alloys after annealing

A study investigated the changes that occur in the structure and magnetostrictive properties of polycrystalline Tb-Dy-Fe casting alloys after annealing. The alloys formed a columnar structure along the thermal flow direction during casting, and the Laves phases tended to show a [110] orientation parallel to the columnar structure. The magnetostriction of the alloys under a condition of compressive prestress changed substantially as a result of annealing, and a pronounced increase in magnetostriction was observed at annealing temperatures above 750/spl deg/C. After annealing, magnetostrictive properties reflected changes in magnetocrystalline anisotropy and the saturation magnetostrictive coefficient due to differences in the Tb/Dy ratio. Annealing had the effect of homogenizing the alloys and easing lattice distortion of the Laves phases.