Apparatus for annealing/magnetic annealing amorphous metal in a

Abstract

A method of heat treating an amorphous metal alloy by immersing the alloy in a fluidized bed to heat the alloy to a temperature below its recrystallization temperature. The alloy is maintained in the fluidized bed for a time sufficient to reduce internal stresses While minimizing crystal growth and nucleation of crystallites in the alloy. Then, the alloy is removed from the fluidized bed and cooled. A magnetic field can be applied to the alloy before, during or after heating the alloy in the fluidized bed. The magnetic field is applied for a time sufficient to achieve substantial magnetic domain alignment while minimizing crystal growth and nucleation of crystallites in the alloy. The cooling step is effective to maintain the magnetic domain alignment in the alloy. The cooling step can be performed with a chill bath or a fluidized bed which is cooled by a circulating gas such as nitrogen or air. The alloy can be slowly cooled by convection and radiation after it is removed from the first fluidized bed. An apparatus for magnetic annealing of amorphous metal alloy cores. The apparatus includes a fluidized bed for heating the core, a conveyor for transporting the core and immersing the core in the fluidized bed and at least one winding for applying a magnetic field to the core. The apparatus can include a chill bath and/or a second fluidized bed for cooling the core. A chamber can be provided between the two fluidized beds for slow cooling the core by convection and radiation prior to cooling the core at a faster rate in the second fluidized bed.