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M: Metallphysik

M 40: Diffusion I

M 40.4: Vortrag

Dienstag, 8. März 2005, 11:15–11:30, TU H2038

Nickel Radiotracer Diffusion in B2 Ordered Ni_50−xFe_xAl₅₀ Alloys — •Sergiy Divinski¹, Frank Hisker¹, Wolfgang Löser², Ulf Södervall³, and Christian Herzig¹ — ¹Institut für Materialphysik, Universität Münster, Germany — ²IFW Dresden, Dresden, Germany — ³Department of Physics, Chalmers University of Technology,Göteborg, Sweden

Ni bulk diffusion was measured in a series of B2 ordered Ni_50−xFe_xAl₅₀ alloys. The ⁶³Ni radioisotope in combination with the serial sectioning technique was applied at higher temperatures and the secondary ion mass spectrometry (the ⁶⁴Ni isotope) was used in a low temperature range. In the temperature interval from 1050 to 1500 K, well-type Arrhenius temperature dependencies were established for all studied compositions. As the Fe content x in the Ni_50−xFe_xAl₅₀ ternary alloys increases, the Ni diffusivity generally increases. The activation enthalpy Q of Ni diffusion changes strongly non-monotonously in the ternary alloys between the binary end-members NiAl and FeAl revealing a pronounced minimum at the Ni₄₀Fe₁₀Al₅₀ composition and a conspicuous maximum around the Ni₂₅Fe₂₅Al₅₀ composition. The latter indicates additional ordering (e.g. of the L2₁ type) in the corresponding alloys.