A Mechanism of Removal of a Glass Envelope from a 'Thick' Amorphous Co-Alloy Wire Prepared by the Ulitovsky-Taylor Method

摘要

Optical and scanning electron microscopy are used to study a mechanism of removal of a glass envelope from a "thick" (D = 96 μm) amorphous wire prepared from a model Co alloy by the Ulitovsky-Taylor method. It is shown that the mechanism of destruction and removal of the glass envelope during pulling of the wire through a cylindrical tool with a hard rough coating is determined by the type and level of stresses that act in the amorphous metal core. The stresses that occur in the longitudinal direction owing to the difference in the linear expansion coefficients of the metal and the glass provide an easy chipping of long (5-15 wire diameters) fragments of the glass envelope. The local stresses induced by the bending of the wire even in the elastic region contribute to the effective destruction of the remaining small fragments of the glass envelope along the directions of the preferred formation of shear bands. High bending stresses arising from the plastic deformation of the amorphous metal core increase the efficiency of removal of the glass envelope, but lead to a decrease in the mechanical and magnetic properties of the metal core owing to the nucleation and propagation of a network of shear bands.