THE STUDY OF PHASE-TRANSFORMATIONS IN NANOCRYSTALLINE MATERIALS

The structure of ferromagnetic amorphous alloys Fe73.5X1Nb3Si13.5B9, with X = Cu, Au, Pt, Pd, has been investigated by TEM, resistometry, dilatometry and magnetic measurements. Nanocrystalline grain formation is observed in these alloys upon crystallization. Ultrafine grains are preserved in alloys with additives which are insoluble in b.c.c.-Fe (Cu, Au), thus forming, together with niobium, a relatively stable interfacial barrier around the grains preventing their growth. In alloys with additives soluble in b.c.c.-Fe, grain sizes increase upon prolonged annealing.