TEM observation and EDX analysis of crystalline phases forming in amorphous Fe73.5Cu1Nb3Si13.5B9 alloy upon annealing

The microstructure and composition of crystalline phases forming in an amorphous Fe73.5Cu1Nb3Si13.5B9 alloy upon annealing have been studied by means of transmission electron microscopy (TEM) and energy disperse X-ray spectra (EDX), respectively. When the alloy is annealed at 450°C, b.c.c. Fe phase, with a grain size of less than 5 nm, precipitates from the amorphous matrix. As the annealing temperature rises, the grain size of the b.c.c. Fe phase increases to about 15 nm. At 600°C, tetragonal Fe3B precipitates, and at 700°C, f.c.c. Fe23B6 appears. The b.c.c. Fe contains about 17 at.% Si, the Fe23B6 phase has about 11 at.% Si and 4 at.% Nb, while in Fe3B there is little Si and Nb.