Nickel self-diffusion in the B₂-compounds NiAl and (Ni,Fe) Al

The intermetallic compound NiAl is one of the most prominent high temperature alloys suitable for advanced technical applications. The compound displays an attractive combination of physical and mechanical properties including high melting point, low density and good oxidation and corrosion resistance. The knowledge of diffusion characteristics and fundamental understanding of diffusion mechanisms are of great importance to the research and design of industrial NiAl-based materials.

Nickel self-diffusion was therefore investigated in dependence on temperature and composition in NiAl single crystals and in selected (Ni,Fe) Al alloys using the radiotracer isotope ⁶³Ni and the enriched isotope ⁶⁴Ni for SIMS analysis of the bulk diffusion profiles. Applying embedded-atom calculations and Monte Carlo simulation the vacancy properties were calculated in this compound, which forms constitutional vacancies and antisite defects, depending on the alloy composition. Probable diffusion mechanisms were calculated and discussed.

Drittmittelgeber:

Deutsche Forschungsgemeinschaft, Alexander von Humboldt-Stiftung

Beteiligte Wissenschaftler:

Dr. S.V. Divinski, Dr. St. Frank, Prof. Dr. Chr. Herzig (Leiter), Dipl.-Phys. F. Hisker, Dr. U. Södervall (Chalmers University of Technology)

Veröffentlichungen:

Divinski, S.V., St. Frank, Chr. Herzig, U. Södervall: The Ni self-diffusion in NiAl: an experimental investigation of the temperature and composition dependencies and atomic simulation of diffusion mechanisms, Sol. State. Phenom. 72, 203 (2000)

Divinski, S., Chr. Herzig: On the six-jump cycle mechanism of self-diffusion in NiAl, Intermetallics, 8, 1357 (2000)

Frank, St., S. V. Divinski, U. Södervall, Chr. Herzig: Ni tracer diffusion in the B2-compound NiAl: influence of temperature and composition, Acta mater., 49, 1399 (2001)

S. V. Divinski, St. Frank, U. Södervall, Chr. Herzig: Tracer measurements of Ni self-diffusion and atomistic calculations of diffusion mechanisms in NiAl, Mat. Sci. Forum, in print

Dissertation:

St. Frank: "Volumen- und Kornprenzendiffusion in geordneten Phasen des Systems NiAl" (1999)