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MM: Fachverband Metall- und Materialphysik

MM 26: Liquid and Amorphous Metals I

MM 26.3: Vortrag

Mittwoch, 27. Februar 2008, 14:30–14:45, H 0107

Diffusion of ³²P, ⁵⁷Co and ¹⁰³Pd in the glass-forming Pd₄₃Cu₂₇Ni₁₀P₂₀ alloy and its relation to viscosity — •Alexander Bartsch¹, Klaus Rätzke¹, Andreas Meyer², and Franz Faupel¹ — ¹Technische Fakultät, Univ. Kiel, Kaiserstr.2, 24143 Kiel — ²Institut für Materialphysik im Weltraum, DLR Köln

Since the development of bulk metallic glasses there has been considerable research effort on these alloys. Due to the high stability against crystallisation the undercooled melt between melting temperature and caloric glass transition temperature is now accessible so that recent theories can be tested.

In general, the Stokes-Einstein equation is well accepted in the equilibrium melt of these alloys. In the supercooled melt a decoupling of diffusivity and viscosity around the critical temperature of the mode coupling theory is observed [1]. Now the ³²P, ⁵⁷Co and ¹⁰³Pd diffusion were measured in a temperature range from 573 K up to 800 K in the Pd₄₃Cu₂₇Ni₁₀P₂₀ alloy using the radiotracer technique. We found that P and Co have similar diffusivities and compared them to viscosity data using SE equation [2]. This shows that the mobility of P and Co do not determine the viscosity in the supercooled state. Based on ongoing experiments with ¹⁰³Pd we now can give an overview on the relation between diffusion and viscosity of all constituents of the alloy.

[1] V. Zöllmer, K. Rätzke, F. Faupel, A. Meyer, Phys. Rev. Lett., 90, 195502-1 (2003).

[2] A. Bartsch, K. Rätzke, F. Faupel, A.Meyer, Appl. Phys. Lett. 89, 121917 (2006)