Structural Changes Induced By Severe Plastic Deformation Of Fe- and Co-Based Amorphous Alloys

Abstract

The amorphous alloys Fe₈₁Si₇B₁₂, Fe₈₁Si₄B₁₃C₂, Fe₆₄Co₂₁B₁₅, Fe_73.5Cu₁Nb₃Si_13.5B₉, and Fe₅Co₇₀Si₁₅B₁₀ prepared as strips by fast melt quenching on the rotating Cu disc were examined. The strips were 6–12 mm wide and 25–40 μn thick. The structure, coercivity and friction coefficient of these amorphous alloys after plastic deformation by tension, rolling, shear pressure, and dry sliding friction were analyzed. The samples underwent mechanical loading at 293 K in air at rates excluding heating of the material. Coercivity was shown to increase by a factor of ten or more at all types of deformation. The electron microscopic study of the structure of deformed strips revealed the presence of crystalline precipitates 2 to 50 nm in size having a relatively equiaxed shape in the amorphous matrix of the Fe-based alloys and a nearly plate shape in the Co-based alloys. The phases were identified from electron microdiffraction patterns of the alloys.