Berlin 2005 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

DS: Dünne Schichten

DS 17: Harte Schichten und mechanische Eigenschaften

DS 17.1: Hauptvortrag

Montag, 7. März 2005, 13:30–14:15, TU HS110

Mechanisms of mechanical deformation in artificial superlattices and self-organized nanostructured thin films — •Lars Hultman — Thin Film Physics Division, Department of Physics, IFM, Linköping University, S-581 83 Linköping, Sweden

Nanostructured thin films are attractive in that materials can be synthesized for tailored mechanical properties. This presentation gives an overview of mechanical deformation mechanisms in different types of nanostructured materials exhibiting superhardening (nitride superlattices and nanocomposites), extreme elasticity (fullerene-like carbon nitride) or reversible plasticity (MAX-phase ceramics). In TiN/NbN superlattices, glide within the layers is shown to be the dominant deformation mechanism in support of theory for superhardening that presumes plasticity with dislocation hindering at interfaces between phases of different shear modulus. Age hardening of ceramic coatings is introduced for advanced surface engineering with the example of metastable TiAlN. Spinodal decomposition with coherent cubic-phase nm-size domains of TiN and AlN that hinder dislocation glide is demonstrated. Thin films of inherently nanolaminated hexagonal Mn-1AXn-phases are produced (n=1,2,3; M=transition metal; A-group element; X=C/N) such as Ti3SiC2. Ductile mechanical deformation is observed with kink formation and cohesive delamination on the basal planes. CNx compounds are resilient (hard and extremely elastic). They consist of sp2-coordinated basal planes that are buckled from the incorporation of pentagons, but also cross-linked due to the substitutional bonding of N. Carbon nitride can store deformation energy by bending of such fullerene-like units.