MICROSTRUCTURE OF DIFFERENTLY ANNEALED NANOCRYSTALLINE FE72.7CU1NB1.8MO2SI13B9.5 ALLOY

The microstructure of differently annealed nanocrystalline Fe72.7Cu1Nb 1.8Mo2Si13B9.5 alloy was investigated by using Mossbauer spectroscopy and transmission electron microscope. The specimens were isochronally annealed at temperatures between 480 degrees C and 600 degrees C for 0 .5 h. The experimental results show that the microstructure mainly con sists of the nanoscale bcc alpha-Fe(Si) grains and the residual amorph ous matrix phase. A trace paramagnetic phase was found for annealing a bout above 500 degrees C. The volume fraction of alpha-Fe(Si) grain in creases with increasing annealing temperature, whereas the average siz e of grain is almost unchanged above 480 degrees C up to 580 degrees C . The calculated thickness of the intergranular layer of the residual amorphous matrix clearly decreases with increasing annealing temperatu re.