PHASE SEGREGATION IN THE FE90ZR10 AMORPHOUS ALLOY UNDER HEATING

A study of the changes in the structure of melt-quenched Fe90Zr10 amor phous alloys by x-ray diffraction, Auger spectroscopy, and transmissio n electron microscopy is reported. The samples were subjected to isoch ronous (for 1 h) and isothermal anneals at 100-650 degrees C. It is sh own 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 cub ic and a weakly tetragonal lattice. Crystallization taking place durin g low-temperature anneals is preceded by phase segregation of the allo y within the amorphous state. The lattice periods of the solid solutio ns have been determined. The possibility of the alloy crystallizing by spinodal decomposition during prolonged annealing is discussed. (C) 1 998 American Institute of Physics. [S1063-7834(98)00110-5].