FE-57 MOSSBAUER STUDY OF METASTABLE-304 STAINLESS-STEEL FILM WITH BCCSTRUCTURE

The metastable 304 stainless steel film with BCC structure, fabricated by using a vapour quenching method, is strongly ferromagnetic. The ef fect of the local environment on the hyperfine parameters, and the inf luence of the heat treatment and pressure on stability in the metastab le phase, were studied by means of conventional and high-pressure Fe-5 7 Mossbauer spectroscopy. Each non-iron nearest-neighbour atom (Cr, Ni and Mn) of Fe atoms decreases the hyperfine field by an average of ab out 2.3 T and the isomer shift by about 0.01 mm s(-1). Moreover, each non-iron next-nearest-neighbour atom is estimated to reduce the hyperf ine field by an average of about 1.2 T. It is found that the transform ation from the metastable sec state to the FCC State begins near 500 d egrees C and is completed near 800 degrees C. No FCC phase appears und er a pressure smaller than 36 kbar. In both cases, however, the magnet ization direction of the sample is observed to reorientate, and shows a stronger tendency to the out-of-plane after annealing and under pres sures up to 8 kbar, while it is closer to the in-plane under pressures larger than 8 kbar.