Berlin 2008 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 23: Poster session
MM 23.37: Poster
Dienstag, 26. Februar 2008, 14:45–18:00, Poster B
Stress impact on reactive diffusion in nano-structures of spherical symmetry — •Constantin Buzau Ene1, Guido Schmitz2, Carsten Nowak1, Talaat Al-Kassab1, and Reiner Kirchheim1 — 1Universität Göttingen, Institut für Materialphysik, Friedrich-Hund Platz 1, D-37077 Göttingen — 2Universität Münster, Institut für Materialphysik, Wilhelm-Klemm-Str.10, D-48149 Münster
Al/Cu/Al and Cu/Al/Cu triple layers with approximately 10 nm single layer thickness are deposited on curved substrates of 25 nm radius and investigated by atom probe tomography. The first reaction product is found after 5 min thermal treatment at 110°C. Surprisingly, the reaction rate depends significantly on the deposition sequence of the metals. Thus, the thickness of the product formed at the interfaces at which Cu is deposited on top of Al is approximately 1.5 to 2 times thicker than that of the opposite stacking sequence. This asymmetry may be explained by stress induced by excess volume of the reaction product. Due to the specific geometry, compressive and dilatational stress is produced on opposite sides of the product layer, even in the case of semi-coherent or incoherent interphase boundaries. The resulting stress gradient leads to additional driving force to the transport of vacancies which accelerates or decelerates the reaction rate in dependence on the stacking sequence of the layer material. By quantitative analysis, the level of induced stress can be quantified from the modified growth rates.