Typical local defects were identified in extended ductile amorphous Co-based alloy wires, having 50 – 110 µm in diameter, obtained by Ulitovsky – Taylor in a continuous process of drawing a jet of melt in a glass shell. The studies found that gas pores and necks are local defects of glass-coated wires. The paper analyses the impact of the dissolved in the metal melt gas and glass-coating stress on the drawing process stability and the geometric parameters of the wire. The formation of hidden pores is due to gas expelling and redistribution of gas following the melt stream solidification. It is noted that gas porosity would not result in spontaneous breaks and changes in wire geometry. The characteristic form of a brittle rupture of an amorphous wire was observed upon fracture by bending in the region of gas porosity. It was in the studies revealing that amorphous wire neck formation was caused by high temperature transverse ring cracking of the glass-coating in contact with quenching liquid. Elastic deformation of amorphous wire in the vicinity of neck flows through the mechanism of formation and sliding transverse shear band. It is noted that the longitudinal destruction of the glass shell does not affect the geometric parameters of the amorphous wire. The procedures for local defects eliminating while producing ductile amorphous wires and the possible prospects for the variable diameter wires manufacturing are proposed.
Surface microstructural design to improve mechanical and giant magneto-impedance properties of melt-extracted CoFe-based amorphous wires
