Auto-organized nanostructures in the Ti-Al-N thin film system
2004 (English)In: SURFACES AND INTERFACES IN NANOSTRUCTURED MATERIALS AND TRENDS IN LIGA, MINIATURIZATION, AND NANOSCALE MATERIALS: Fifth MPMD Global Innovations Symposium / [ed] Mukhopadhyay, SM; Seal, S; Dahotre, N; Agarwal, A; Smugeresky, JE; Moody, N, John Wiley & Sons, 2004, 163-172 p.Conference paper (Refereed)
Age hardening by spinodal decomposition in ceramic thin film systems is reviewed. This is a new concept for advanced surface engineering with applications for wear-resistant coatings in machining processes like high-speed and dry cutting. The reactive arc deposition method with relatively low substrate temperatures is employed to produce supersaturated solid solutions of the material by ion-bombardment-induced mixing of atoms and kinetic limitation to reduce thermodynamically-driven segregation during synthesis. It is shown using electron microscopy, X-ray diffraction, and nanoindentation techniques that Ti1-xAlxN (0 less than or equal to x less than or equal to 1) coatings with compositions in the miscibility gap undergo spinodal decomposition during annealing at temperatures between similar to900 degreesC and 1100 degreesC. As a result, coherent cubic-phase nanometer-size domains form that cause an increase in hardness. These intermediate metastable domains transform into their stable phases TiN and hexagonal wurtzite-structure AlN during further thermal treatment. The findings are corroborated by Ab initio calculations of phase stability and molar volume for competing phases. Activation energies for the processes indicate defect-assisted segregation of Ti and Al. It is inferred that the success of Ti1-xAlxN coatings is not only based on its superior oxidation resistance, but also on its ability for self-adaptation to the thermal load applied during cutting by age hardening. The findings and experimental approach have implications also for other ternary and multinary ceramic systems including the group-III nitride alloys.
Place, publisher, year, edition, pages
John Wiley & Sons, 2004. 163-172 p.
transition metal nitrides; TiAlN; aging; self-assembly; nanocomposite; thin films; spinodal decomposition; hard materials; electron microscopy; nanoindentation
National CategoryEngineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-75420ISI: 000189464100017ISBN: 978-0-87339-566-3OAI: oai:DiVA.org:liu-75420DiVA: diva2:506564
5th Global Innovations Symposium held at the 2004 TMS Annual Meeting Charlotte, NC, USA March 14-18, 2004