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MM: Metall- und Materialphysik
MM 8: Symposium Modern Metallic Materials Design II
MM 8.2: Talk
Monday, March 27, 2006, 15:00–15:15, IFW B
Computer simulation of the field evaporation in TiAl with additions of Nb — •Torben Boll1, Talaat Al-Kassab1, Yong Yuan2, and Zhi-Guo Liu2 — 1Institut für Materialphysik der Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen — 2Laboratory of Solid State Microstructures, Nanjing University, Hankou Road 22, Nanjing 210093, China
The formation of an image in the field ion microscope and subsequently the field assisted evaporation of the upper most surface atoms from the atomic layers as originated in the tomographic atom probe were simulated. As a model system we have selected the ordered structure of the γ-TiAl-phase with a L10-unit cell containing various additions of Nb. For the first time in such a computer modeling next neighbor (NN)-binding energies have been used. The effect of site occupation and concentration of Nb on the process of field evaporation and its influence on the TAP- and FIM-results were investigated as well. Further algorithms were developed to explore the vicinity around selected species and hence to analyze the degree of order based on TAP results. These processes were tested on experimental as well as on simulated data. In this contribution the computer model will be presented and discussed. In particular the focus will be emphasized on the approach to estimate NN-binding energies and order parameters by comparing the simulations with experimental data.