Fachbereich 11 - Physik
Institut für Materialphysik
Diffusion in Metals, Intermetallics, Silicides, Quasicrystals and Metallic Glasses

Diffusion Al-Fe intermetallics

Diffusion of several foreign elements (Zn, In, Cr, Mn, Co and Ni) and self-diffusion of iron was studied in the intermetallic phases Fe³Al, Fe²Al and FeAl using the radiotracer method in combination with serial sectioning for diffusion profile determination. The diffusivities of all foreign elements and Fe self-diffusion decreases slightly with increasing Al content. In Fe³Al the ordering transition from the B2 ordered to the disordered A2 structure has only a small influence on the diffusion behaviour: For Fe, In, Zn, Cr and Mn the activation enthalpy is slightly higher in the ordered B2 structure. A correlation was observed between the diffusivities of foreign elements an their site preference deduced from ab-initio calculations in the ordered structure.: The diffusion of foreign elements incorporated preferentially in the Al sublattice is slightly faster than Fe self-diffusion; foreign elements preferentially incorporated in the Fe sublattice diffuse slower that Fe and have higher activation enthalpies.

We studied also interdiffusion in single phase diffusion couples in the Fe-Al system employing electron microprobe analysis. Interdiffusion coefficients were deduced by the Boltzmann-Matano method. Using the Darken-Manning equation, our experimental Fe tracer diffusivities and theoretical values of the thermodynamic factor calculated in cooperation with an israelian group we deduced values for the Al tracer diffusivities, which are not accessible to direct experiments due to the lack of a suitable Al tracer isotope. The results show that Fe and Al diffusion proceed at very similar rates.

Drittmittelgeber:

German-Israel Foundation of Scientific Research and Development (GIF)

Beteiligte Wissenschaftler:

Prof. Dr. S. Dorfman (Technion Haifa, Israel), Prof. Dr. D. Fuks (Ben Gurion University, Beer Sheva, Israel), Dr. S. Divinski, Prof. Dr. H. Mehrer (Leiter), Dipl.-Phys. S. Peteline, Dipl.-Phys. M Salamon, Dipl. Phys. E. M. Tanguep Njiokep

Veröffentlichungen:

Eggersmann, M., H. Mehrer:Tracer diffusion in iron-aluminides, Defect and Diffusion Forum 194 - 199, 467 - 472 (2001)

Salamon, M., S. Dorfman, D. Fuks, G. Inden, H. Mehrer: Interdiffusion and diffusion of Al in iron-aluminides, Defect and Diffusion Forum 194 - 199, 553 - 558 (2001)

Peteline, S., E. M. Tanguep-Njiokep, S. Divinski, H. Mehrer: Diffusion of solute elements in Fe₃Al, Defect and Diffusion Forum 216 -217, 175 - 180 (2003).