Phase segregation in the Fe90Zr10 amorphous alloy under heating

A study of the changes in the structure of melt-quenched Fe90Zr10 amorphous alloys by x-ray diffraction, Auger spectroscopy, and transmission electron microscopy is reported. The samples were subjected to isochronous (for 1 h) and isothermal anneals at 100-650 degrees C. It is shown that an amorphous alloy annealed for one hour at 300-500 degrees C crystallizes with formation of a supersaturated solid solution of Zr in alpha Fe and the intermetallic compound Fe3Zr. Isothermal anneal at 100 degrees C for up to 7000 h produces nanocrystallites 110-30 nm in size, with fuzzy interfaces between the grains. An alloy subjected to such an anneal contains two solid solutions of Zr in Fe, having a cubic and a weakly tetragonal lattice. Crystallization taking place during low-temperature anneals is preceded by phase segregation of the alloy within the amorphous state. The lattice periods of the solid solutions have been determined. The possibility of the alloy crystallizing by spinodal decomposition during prolonged annealing is discussed. (C) 1998 American Institute of Physics. [S1063-7834(98)00110-5].