MULTICOMPONENT FE-BASED GLASSY ALLOYS WITH WIDE SUPERCOOLED LIQUID REGION BEFORE CRYSTALLIZATION

The glassy alloy containing 2 at% Ge in the Fe74-xAl5P11C6B4Gex system was found to cause the extension of the supercooled liquid region, Delta T-x(=T-x-T-g) defined by the difference between crystallization temperature (T-x) and glass transition temperature (T-g) to 60 K, though the Delta T-x value of the Ge-free Fe74Al5P11C6B4 glassy alloy is 45 K. The remarkable increase in Delta T-x is attributed to the increase in T-x exceeding the degree of the increase in T-g. The Fe72Al5P11C6B4Ge2 glassy alloy has good bending ductility and ferromagnetism with Curie temperature at 590 K, in addition to the appearance of the wide supercooled liquid region. The crystallization of the glassy alloy containing 2% Ge takes place through a single stage and the crystallized structure consists of alpha-Fe, Fe3P, Fe3C, Fe3B and Fe2B phases. There are no appreciable changes with Ge content in the crystallized structure and the single-stage crystallization process leading to the simultaneous precipitation of the five crystalline phases. The effectiveness of 2% Ge on the increase in Delta T-x is presumably due to the retardation of crystallization caused by the decrease in the formation tendency of Fe3C, Fe3B and F2B phases resulting from the existence of Ge which is soluble to Fe and insoluble to B and C.