Production process of grain orientation-controlled Fe–6.5 mass% Si alloy fiber using spinning in gas atmosphere followed by winding in rotating liquid

Abstract

A new process where a melt jet is quenched in gas followed by winding in a rotating liquid, which is a modified process of the in-rotating-water-spinning Process (INROLISP), has been developed in order to make continuous Fe–6.5 mass% Si alloy fiber with primary dendrite arms parallel to the fiber axis, having nearly zero magnetostriction. The molten alloy is ejected from a nozzle through a He gas zone located just under the nozzle, followed by an O 2 gas zone. He gas protects the orifice from plugging with metal oxides. The oxygen in the next zone forms a metal oxide sheath on the jet surface to restrain the jet from breaking up. The straight jet covered with oxide film continuously solidified and caused recalescence. After the recalescence the fiber was wound in a rotating liquid. Without the oxidization zone, such as only He or only NH 3 vapor, the jet was more rapidly cooled but became fractured. In case of CO 2 in the oxidization zone, the jet became fractured and led to short fibers. The capillary breakup length of a jet ( L BU ) can be calculated by L BU = K · V ·( ρ · d 3 / γ ) 1/2 , where V is mean velocity of a jet, ρ the density of the molten alloy, d the diameter of nozzle, and γ the surface tension of the molten alloy. In this work, the coefficient K was estimated as 10–20 from the experimental results for the He zone length and the velocity of the jet. The spinning gap between the nozzle exit and the rotating liquid surface was set 0.2–1.0 m which is longer than the length between the nozzle exit and the start of recalescence. Fibers about less than 100 μm in diameter, longer than 10 m in length, having a large Barkhausen effect were obtained.