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MM: Metall- und Materialphysik
MM 8: Symposium Modern Metallic Materials Design II
MM 8.1: Talk
Monday, March 27, 2006, 14:45–15:00, IFW B
Investigation of the phase boundary and site occupation of atoms in pure and doped TiAl/Ti3Al intermetallic by means of the tomographic atom probe (TAP) — •Torben Boll1, Talaat Al-Kassab1, Yong Yuan2, and Zhi-Guo Liu2 — 1Institut für Materialphysik der Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — 2Laboratory of Solid State Microstructures, Nanjing University, Hankou Road 22, Nanjing 210093, China
Dual-phase TiAl/Ti3Al alloys consisting of a lamellar structure, comprising γ-phase plus a small amount of α2-phase, with addition of 1 and 5at.%Nb were prepared. The samples were investigated by means of the field ion microscopy (FIM), the tomographic atom probe (TAP) and supporting TEM, HRTEM analysis. The influence of Nb-alloying on the variation of the field evaporation and microstructural parameters in the γ-phase as studied by FIM and TAP will be reported in this contribution. A new data treatment approach based on TAP results was developed to evaluate the site occupancies in such ordered structures. The Nb-atomic site occupancies, as well as any clustering and/or ordering of Nb atoms will be reported. In addition, computer modeling and simulation of the field evaporation behavior of the different species including the next neighbor interaction in a FIM specimen are performed for the first time. From these simulations, a structural order parameter and binding energies for the different species can be estimated. A comparison of the results, obtained with this model, to the experimental data will be presented and discussed for the site occupancy of Nb in these alloys.