Internal stress distribution in DC joule-heated amorphous glass-covered microwires

As known, the magnetic properties of AGCMs are determined by the radial, azimuthal and axial internal stresses induced during both the preparation process and the Suitable thermal treatments of these microwires. In this paper we have proposed a theoretical model in order to determine the total internal stresses induced during the dc joule-heating thermal treatment (heating-crystallization-cooling). In this view (i) we have started from the internal stress values obtained in the preparation process, (ii) we have considered the supplementary axial tensile stresses due to the mechanical drawing of the microwire during the preparation process and (iii) we have taken into account the difference between the thermal expansion coefficients of metal and glass. We have found that (i) the maximum value of the axial stresses obtained after the thermal treatment is bigger than that obtained in the preparation process., the difference being about 450 MPa, (ii) the maximum values for the azimuthal and radial stresses decrease by congruent to 220 and congruent to 210 MPa respectively, (iii) the dimensions of the cylindrical inner core increase significantly (by congruent to 13%), which involves an increase of the degree of magnetic order in the AGCMs and consequently leads to the appearance of a large Barkhausen effect (LBE) in low axially applied magnetic fields and (iv) the reduced remanence increases from 0.90 to 0.95.