EXAFS analysis of grain boundaries in nanocrystalline Fe sub 85 Zr sub 7 B sub 6 Cu sub 2 alloys

• Published in: Journal of alloys and compounds 1998-06, Vol.286 (1-2), p.103-107
• Main Authors: Sobczak, E, Swilem, Y, Nietubyc, R, Dluzewski, P, Slawska-Waniewska, A
• Format: Article
• Language: English
• ISSN: 0925-8388

Nanocrystalline Fe sub 85 Zr sub 7 B sub 6 Cu sub 2 alloys were obtained from the formerly amorphous Fe sub 85 Zr sub 7 B sub 6 Cu sub 2 alloy by a heat treatment at several temperatures ranging from 480 deg C to 600 deg C. The ultrafine nanocrystalline structure of bcc-Fe grains with a grain size of 3-15 nm diameter embedded in an amorphous matrix was established using transmission electron microscopy. X-ray absorption spectra at the Fe K-edge for Fe sub 85 Zr sub 7 B sub 6 Cu sub 2 amorphous and nanocrystalline alloys and metallic Fe foil were measured using synchrotron radiation. Fourier analysis of extended x-ray absorption fine structure (EXAFS) for alloys was performed and two models of grain boundaries in nanocrystalline Fe sub 85 Zr sub 7 B sub 6 Cu sub 2 alloys were proposed. The heat treatment of alloys at temperatures of 480 deg C and 500 deg C creates simple boundaries between crystalline grains and amorphous matrix, while the heat treatment at higher temperatures from 540 deg C to 600 deg C can produce boundaries in the form of Fe-free interfaces with thickness of about 0.3 nm. A model of an Fe-free interface being a barrier for grain growth can explain the nanocrystallization phenomenon of Fe sub 85 Zr sub 7 B sub 6 Cu sub 2 alloys.