Regensburg 2000 – scientific programme
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M: Metallphysik
M 6: Struktur und Umwandlung II
M 6.4: Talk
Tuesday, March 28, 2000, 11:00–11:15, H16
Effect of Ti and microstructure on the kinetics of the σ-phase formation in the Fe-Cr alloys — •Stanislaw M. Dubiel1, Artur Blachowski1, Jakub Cieslak1, and Bogdan Sepiol2 — 1AGH University, Al. Mickiewicza 30, PL-30-059 Krakow — 2Universitaet Wien, Strudlhofgasse 4, A-1090 Wien
Results obtained by means of Mössbauer Spectroscopy on the
effect of Ti in a series of Ti-doped quasi-equiatomic Fe-Cr alloys
with two various microstructures will be reported. The samples
with large grains ( 385 µ m) were transformed into the σ-phase
by an isothermal annealing at 973 K and the spectra were recorded
at RT. The samples with small grains ( 31 µ m) were studied
in situ. In both cases the kinetics of transformation could be
well described in terms of the Johnson-Avrami-Mehl equation which
yielded the kinetics parameters n and k. Assuming the k-values
follow the Arrhenius law, the difference in the activation energy,
E, due to the microstructure and Ti-content was determined.
In particular it was found that the transformation: (1) was
faster in the small grain samples with the difference in E
equal to about 8 kJ/mol, and (2) was accelerated by Ti if its
concentration was less than 1.5 at%, and retarded otherwise.