Some Factors on Surface Crystallization of Fe-Based Amorphous Alloys with Al and Ti Impurities

Abstract

The effects of quench rate during casting and alloy composition on surface crystallization and the magnetic properties are investigated for amorphous Fe-Si-B alloys containing Al and Ti as impurities. In the presence of these impurities, the amorphous alloys tend to be surface-crystallized. Furthermore, the surface crystallization is more prominent at low quench rates. Also, the alloys of high Fe content (low glass forming ability) are found to have the same tendency. TEM observation of the free side of the ribbons reveals that there is a big difference between Al and Ti in crystallization behavior. These phenomena are supposed to originate from the difference in lattice coherency between α-Fe and the precipitates in which two impurities act as nuclei of crystallization.