NANOCRYSTALLINE IRON-BASED ALLOYS INVESTIGATED BY MOSSBAUER SPECTROMETRY

Nanocrystalline alloys exhibit great fundamental and technological int erests because of their microstructural properties, and their excellen t soft magnetic properties. Fe-57 Mossbauer spectrometry is a well sui table technique to investigate Fe-based nanocrystalline alloys: its lo cal probe behaviour permits to elucidate the nature of hyperfine inter actions at different resonating iron nuclei and to distinguish their i mmediate atomic surroundings. We review on the recent Mossbauer develo pments performed on first FeCuMBSi and then FeCuBSi nanocrystalline al loys. From Mossbauer studies, one can estimate the crystalline (i.e., amorphous) fraction, the Si-content in Fe-Si nanocrystalline grains em erging from amorphous alloys of the first series, the temperature depe ndence of magnetic behaviours of both crystalline and amorphous phases ; finally, we present a novel fitting procedure applied to FeCuBSi nan ocrystalline alloys which result from bcc-Fe crystalline grains embedd ed in an amorphous matrix. In this case, the hyperfine structure is ab le to model the intergranular phase.