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Structure and failure of Fcc/Bcc heterophase boundaries in metals

: Hashibon, A.; Elsässer, C.; Gumbsch, P.

Sigl, L.S. ; Plansee AG, Reutte:
17th Plansee Seminar 2009. International Conference on High Performance P/M Materials. Vol.3 : Reutte, Austria May 25-29,2009
Reutte: Plansee, 2009
Plansee Seminar <17, 2009, Reutte>
International Conference on High Performance P/M Materials <2009, Reutte>
Fraunhofer IWM ()
ab initio; molecular dynamic; thin film; thermal stability; wetting; tantalum; copper

The atomistic structure, thin-film stability, and mechanical failure processes at fcc/bcc heterophase boundaries are studied in the Cu-Ta model system by ab initio density functional theory (DFT) calculations and molecular dynamics (MD) simulations. For thin films, Cu is found to dewet from Ta, leaving a single stable semi-coherent monolayer of Cu on Ta. For bulk systems, the first Cu layer at the interface is found to exhibit a distinct, mixed fcc-bcc structure from the rest of the fcc Cu. This layer facilitates the transition from the bcc to the fcc crystal structures across the interface. Mechanical failure under tensile stress is found to occur above this first Cu interface layer.