Generation of a transverse field for annealing amorphous alloys (abstract)

Abstract

In amorphous alloys, the direction and magnitude of the magnetic field during annealing has a profound effect on the induced magnetic properties. Some applications require the annealing field to be at right angles to the ribbon being annealed. Only cumbersome methods exist for generating a field other than along the length of the ribbon. The purpose of this paper is to demonstrate a new and improved method for generating a field 30°–90° away from the long axis of the ribbon. Two sheets of electrical steel are bent into a square tube such that one of the sides is inside the annealing furnace with the edge of the tube along the length of the furnace. The two sheets of steel are separated by a spacer to permit an amorphous ribbon to be passed between the sheets. The steel sheets are lap-joined outside the furnace and enclosed in a coil. Magnetic field is set up in the electrical steel by means of dc current in this coil. The field strength in the steel is adjusted by means of the electrical current and the direction by twisting the whole tube. The amorphous alloys have a much lower coercivity and a much higher permeability than common electrical steel, thus, the induced field will cover the required range and the magnetic flux will be transferred to ribbon during annealing.