Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2018)
    Thin Films Wednesday Sessions
       Session TF-WeM

Invited Paper TF-WeM8
Self-organized Nanostructure Formation in Functional Nitride Alloy Thin Films – Playing Games with Physical Metallurgy

Wednesday, December 5, 2018, 10:20 am, Room Naupaka Salons 4

Session: Nanostructural and Surface Morphological Evolution: Experiment and Theory
Presenter: Lars Hultman, Linkoping University, Sweden
Correspondent: Click to Email
This presentation reviews a multitude of tricks that can be used to promote self-organized nanostructuring in materials. These are used to enhance mechanical and electronic properties for transition metal and group-III nitride alloy thin films prepared by physical vapor deposition. The structural design is obtained by surface- and bulk-driven phase transformation in metastable TiAlN, ZrAlN, HfAlN, TiSiN, MoVN, VWN, and InAlN model systems, and analyzed by XRD, HREM, FIB, APT, and phase field modeling. Ab initio calculations are employed to assess phase stability and decomposition behavior from lattice mismatch and electronic band structure effects. The concept of age hardening in transition metal nitride alloys is reviewed for isostructural model systems. Spinodal decomposition is thus established for TiAlN by the formation of cubic-phase nm-size domains in a checker-board-pattern of TiN and AlN at temperatures corresponding to cutting tool operation. 2-D-nanolabyrinthine structuring in ZrAlN is obtained from with intergrowth of non-isostructural phases c-ZrN/w-AlN: {110}║{11-20} interfaces. Superhardening in TiN/Si3N4 nanocomposites takes place due to Si segregation forming a few-monolayer-thick SiNx tissue phase, which is a vacancy-stabilized cubic-SiNx layer. A hardness maximum at 34 GPa – short of ultrahard - is observed in TiN/SiNx(001) superlattices at the epitaxial-to-amorphous thickness-limit for the SiNx layers. Thermodynamically-driven Si segregation in c-Ti1-xSixN is proven in atom probe tomography on the sub-nm scale using 15N isotopic substitution to resolve mass spectral overlap between Si and N. For InxAl1-xN, we report curved-lattice epitaxial growth of nanospirals with controllable chirality as well as core-shell nanorod formation. Finally, the possibility to intercalate atomic layers of Au in non-Van-der Waals nanolaminated Ti3SiC2 (MAX phase) is demonstrated.