| AVS 55th International Symposium & Exhibition | |
| Advanced Surface Engineering | Wednesday Sessions |
| Session SE-WeM |
| Session: | Atmospheric Pressure Treatments and Hard and Nanocomposite Coatings |
| Presenter: | L. Hultman, Linköping University, Sweden |
| Authors: | A. Flink, Linköping University, Sweden M. Beckers, Linköping University, Sweden B. Alling, Linköping University, Sweden J. Bareno, Linköping University, Sweden J. Sjölen, Seco Tools AB, Sweden I. Abrikosov, Linköping University, Sweden L. Hultman, Linköping University, Sweden |
| Correspondent: | Click to Email |
Arc-Evaporated (Ti1-xSix)Ny thin solid films have been studied by analytical electron microscopy, X-ray diffraction, scanning tunneling microscopy, X-ray photoelectron spectroscopy, elastic recoil detection analysis, and nanoindentation. As-deposited films form cubic solid solutions with Si substituting for Ti up to x = 0.09. Si segregation in films with higher Si content, up to x = 0.20, results in a feather-like microstructure consisting of cubic TiN:Si nanocrystallite bundles with low-angle grain boundaries and a very high dislocation density of 1014 cm-2 (corresponding to a cold-worked alloy). Correspondingly, N content in the films increases almost linearly with Si content from y = 1.00 for x = 0 to y = 1.13 for x = 0.20. Upon annealing at 1000 °C, films with Si contents between x = 0.04 and 0.20 develop a metastable crystalline SiNz (1.0 ≤ z ≤ 1.33) tissue phase, which is semicoherent to TiN. These films exhibit retained hardness between 31-42 GPa and are compositionally stable. Thus, superhard TiN-SiNz nanocomposites without amorphous silicon nitride phase can be produced by arc-evaporation and subsequent annealing. At 1100-1200 °C, the films soften due to amorphization of the SiNz tissue phase, followed by recrystallization of the TiN grains, and Si and N diffusion out of the film. Ab-initio calculations performed in parallel to these experiments reveal that c-Si3N4 can be stabilized with D022 or L12 ordered Si vacancies in a ZnS-like structure, in agreement with previous experimental results published by us,1-3 while phonon calculations show that stoichiometric c-SiN is dynamically unstable in the NaCl and ZnS structures.4,5
1Hans Söderberg, Jon Molina-Aldareguia, Lars Hultman, and Magnus Odén, J. Appl. Phys. 97 (2005) 114327.
2Lars Hultman, Javier Bareño, Axel Flink, Hans Söderberg, Karin Larsson, Vania Petrova, Magnus Odén, J. E. Greene, and Ivan Petrov, Phys. Rev. B75 (2007) 155437.
3Hans Söderberg, Axel Flink, Jens Birch, Per O.Å. Persson, Manfred Beckers, Lars Hultman, and Magnus Odén, J. Materials Research 22 (2007) 3255.
4Axel Flink, PhD Thesis “Growth and Characterization of Ti-Si-N Thin Film” Linköping Studies in Science and Technology, Dissertation No. 1190, Linköping, Sweden (2008). www.ep.liu.se.
5B. Alling, E. I. Isaev, A. Flink, L. Hultman, I. A. Abrikosov, submitted.