Dresden 2003 – scientific programme

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M: Metallphysik

M 32: Intermetallische Phasen II

M 32.2: Talk

Wednesday, March 26, 2003, 16:45–17:00, IFW B

Nickel and Iron Tracer Diffusion in B2 Ni₄₀Fe₁₀Al₅₀ Ternary Alloy — •S. Divinski¹, F. Hisker¹, Y.-S. Kang², W. Löser³, U. Södervall⁴, and Chr. Herzig¹ — ¹Institut für Materialphysik, Universität Münster, Münster, Germany — ²Dep. Metallurgy and Materials Science, Hanyang University, Ansan, Korea — ³IFW Dresden, Dresden, Germany — ⁴Dep. Physics, Chalmers University of Technology, Göteborg, Sweden

The B2 binary alloy NiAl is a structural material for high-temperature applications. However, poor ductility at room temperature and insufficient creep resistance limits its industrial application. Addition of 10% of Fe was shown to improve the creep resistance. This finding was related to a minimum in the diffusion coefficient [1].

In the present work, Ni and Fe bulk diffusion in Ni₄₀Fe₁₀Al₅₀ ternary alloy is investigated by means of radiotracer measurements (⁶³Ni and ⁵⁹Fe) and SIMS analysis (⁶⁴Ni) in an extended temperature interval from 1000 to 1550 K. The results show that Ni and Fe diffuse in Ni₄₀Fe₁₀Al₅₀ faster than in stoichiometric NiAl and the activation enthalpy of Ni diffusion is remarkably smaller in Ni₄₀Fe₁₀Al₅₀ (∼250kJ/mol) as compared to stoichiometric NiAl (∼290kJ/mol). Moreover, the activation enthalpy of Ni diffusion in Ni_50−xFe_xAl₅₀ ternary alloys was found to reveal a minimum for ternary compositions with about 10% Fe addition. The diffusion mechanism and the controversial behavior of the creep resistance and the self-diffusivity in the NiFeAl ternary alloys is discussed.

[1] G. Sauthoff: Intermetallics (VCH Verlagsgesellschaft mbH, Weinheim, New York) 1995