Mechanical properties of magnetic Fe-based and Co-based amorphous wires and microwires

In this paper we present measurements of the mechanical properties of magnetically soft Fe-based and Co-based conventional amorphous wires (CAW) and glass-covered amorphous microwires (GCAW) in the as-quenched state, before and after cold rolling, and after annealing for internal stresses relief. The tensile strength (sigma) varies between 2000 MPa and 3400 MPa, strongly depending on CAW diameter and annealing temperature. The Young modulus (E) is following a descendant trend, decreasing with the diameter decrease. The increase of tensile strength (sigma) and elongation (epsilon) values after cold-rolling and post-annealing is caused by the release of the internal stresses induced during the preparation. Tensile strengths up to 3900 MPa are achieved for Fe-based GCAW, depending very strongly on the microwires diameter, but mostly on the glass cover thickness. a reaches the maximum value of 3150 MPa for a Co-based microwire having the glass cover of 9 mu m and the total diameter of 43 mu m, but increases even more after the glass removal (3350 MPa). This behaviour is attributed to the structural disorder and the specific magnetic domains structure in Fe-based and Co-based CAW and GCAW. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim