The control of engineering magnetostriction in metallic glasses

Measurements of the field and magnetization dependence of magnetostriction as a function of thermal treatment and specimen surface finish are reported for an iron-rich metallic glass. If surface oxidation is avoided the magnetostriction for any field is increased after annealing. Maximum engineering magnetostrictions of the order of 40 p.p.m. are presented. Standard samples of METGLAS 2605SC (Fe₈₁B_13.5Si_3.5C₂) 5 cm*1 cm * 35 mu m, and special production samples 5 cm*1 cm*25 mu m were prepared from the edges and centre of 2.5 cm wide strip. The surfaces of the special samples away from the casting substrate were particularly smooth. All heat treatments were performed in air. In some cases the samples were placed onto a large preheated aluminium plate; in other cases they were introduced to the furnace on a cold plate of aluminium which slowed the sample heating rate. Cooling of the samples was at an estimated rate of 100 K/s, again in air.