Influence of heat treatment on magnetostrictions and electrical properties of (Fe1Co1)76Mo8Cu1B15

The investigation of magnetostriction of (Fe1Co1)(76)Mo8Cu1B15 metallic glass upon structural changes has been performed on samples with different thermal history. The samples have been annealed for 0.5 h at different temperatures ranging from 573 to 973 K. Measurements of saturation magnetostriction lambda(S), volume magnetostriction omega and forced magnetostriction partial derivative omega/partial derivative H have been performed using direct capacitance method. For the set of annealed samples, the temperature dependence of lambda(s) exhibits local maximum at 828 K. Above 828 K, there is a decrease of lambda( s) by about 1/3 of its maximal value. The dependence of the value of partial derivative omega/partial derivative H on the annealing temperature exhibits local minima at 573 and 923 K and local maximum at 678 K. These extremes in lambda(S) and partial derivative omega/partial derivative H are related to the changes in CSRO and TSRO, to relaxation processes and to internal stresses. The transformation process has been monitored by temperature dependencies of electrical resistivity. Amorphous samples crystallized after annealing at temperatures above 678 K into nanocrystalline supersaturated solid solution bcc-Fe(Co, Mo) and above 873 K into B24Fe84Mo8, CoMoB and traces of B2Mo2Fe and tetragonal Fe3B. As-quenched samples exhibit the Curie temperature at around 600 K, in the vicinity of the glass transition temperature. At room temperatures, the ribbon exhibits isotropic characteristics. Thermal treatment induces magnetic anisotropy formed in the direction parallel to the ribbon axis during relaxation annealing while during crystallization its direction becomes perpendicular to the ribbon axis. Remanence appears after heat treatment above 920 K. (C) 2008 Elsevier B.V. All rights reserved.