Abstract
It has been found that soft magnetic properties such as the coercive force and the permeability of 6.5 mass% silicon-iron ribbons prepared by a rapidly quenching roller method can be improved by annealing at 1373 K in a vacuum atmosphere. In the annealed ribbons, grains have the average size larger than 1 mm, and the ribbon surface is parallel to (100) plane. This paper reports results on the grain growth during annealing and texture formation in the 6.5 mass% silicon-iron ribbons.
In the as-prepared ribbon, non-oriented columnar grains about 10 μm in diameter were observed, which grew from the surfaces to the inner part of the ribbon. When the annealing temperature was around 973 K, the primary recrystallization was formed near the middle part of the ribbon thickness, and the grain size increased with increasing annealing temperature. At the annealing temperature of 1223 K, the grain size became 30-40 μm. Around the annealing temperature, the motive force of the grain growth is the grain boundary energy. However, above 1223 K the surface energy plays an important role in the observed grain growth. When the ribbons were annealed at 1373 K, the grains whose (100) planes were parallel to the ribbon surface grew, and all ribbon surfaces were covered with these grains after 1 hour annealing. When the annealing temperature was kept above 1473 K, the grains with (110) planes parallel to the ribbon surface grew, and all ribbon surfaces became parallel to (110) plane.
