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M: Metallphysik
M 26: Postersitzung
M 26.6: Poster
Donnerstag, 25. März 1999, 15:00–19:00, Aula
Aluminum and Silicon Diffusion in Fe–Cr–Al–Alloys — •A. Heesemann1, E. Schmidtke1, F. Faupel1, J. Kl"ower2, and A. Kolb–Telieps2 — 1Technische Fakult"at der Christian–Albrechts–Universit"at zu Kiel, Lehrstuhl f"ur Materialverbunde, Kaiserstra"se 2,
24143 Kiel — 2Krupp VDM GmbH, Plettenberger Stra"se 2, 58778 Werdohl
Interdiffusion of Al86.4Si13.6 and
Fe79.03Cr19.03Al1.14Si0.8 alloys
(Crofer 18TM)
was studied by means of electron microprobe analysis, scanning electron
and optical microscopy, as wall as X–ray analysis. Formation of intermetallic
phases during interdiffusion was only observed for Al concentrations
cAl>30 at%.
Effects of deviations from the Boltzmann–Matano and the thin–film
geometry on the resulting diffusivities were assessed numerically.
The results are of general interests for diffusion measurements
involving samples of given geometry as in many industrial
applications.
The tracer diffusivities of Al, Si, in Fe79.03Cr19.03Al1.14Si0.8 turned to be quite similar and close to the Fe diffusivity. They are somewhat smaller than in pure Fe. The intrinsic diffusion coefficient of Al exhibits a small increase with increasing Al concentration up to cAl<20 at% mainly due to a corresponding increase in the thermodynamic factor. Interdiffusion at high Al concentrations proved to be much faster and is hence not rate limiting.