Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 50: Topical Session Modern Atom Probe Tomography IV - Thin Films and Structural Materials

MM 50.2: Vortrag

Donnerstag, 29. März 2012, 12:00–12:15, H 0107

Phase Separation in Immiscible Copper-Tantalum Alloy Films — •Claudia M. Mueller¹, Stephan S.A. Gerstl², Alla S. Sologubenko¹, and Ralph Spolenak¹ — ¹Laboratory for Nanometallurgy, Dept. of Materials, ETH Zurich, Switzerland — ²EMEZ Center for Electron Microscopy, ETH Zurich, Switzerland

Phase separation in binary alloys of immiscible elements is investigated on the copper-tantalum system. The alloys are prepared by co-sputtering followed by annealing to induce phase separation. Local Electrode Atom Probe (LEAP) Tomography in combination with Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) is used to study the evolution of phase separation. Results show that in the amorphous copper-tantalum alloys phase separation is coupled to the crystallization of the individual phases. Phase separation starts with the formation of Cu-rich clusters in the still amorphous matrix at temperatures lower than 400^∘C; the clusters contain up to 10 at% Ta and have a FCC structure with (111) texture. At 600^∘C the amorphous matrix crystallizes into a β-Ta structure with up to 7 at% Cu dissolved within. It is observed that GBs between Ta nanograins in this sample are enriched with Cu. The amount of Ta that is dissolved in the Cu phase decreases during annealing. The atomic distributions of Cu and Ta in the respective Ta-rich and Cu-rich phases will be discussed in terms of cluster formation and phase growth.