Characterization of Oxygen-rich Ti2AlC Thin Films
Independent thesis Advanced level (degree of Master), 20 points / 30 hpStudent thesis
In this Thesis Ti-Al-C thin films deposited by cathodic arc at 700, 800 and 900 °C were investigated with respect to composition, structure and mechanical properties. The highest growth temperature resulted in close to single crystalline Ti2AlC MAX phase.
A high oxygen incorporation of 7-12 at.% was detected in all the films, likely originating from residual gas and the Al2O3 substrate. It was evident that the characteristic nanolaminated MAX phase structure was retained upon deflection from the ideal MAX phase stoichiometry.
Hardness and elastic modulus of the sample grown at 900 °C were 16 and 259 GPa, respectively, as determined by nanoindentation using a Berkovich tip. Nanoindentation measurements with a cube corner tip were also performed on all three samples in order to extract elastic moduli.
Analysis of loading-unloading curves and SPM images revealed no relation between pop-in events and pile-ups around the residual imprints, indicating that other mechanisms than formation of kink bands may be responsible for formation of pile-ups. This was also confirmed by cross-sectional TEM investigation of an indent: Ti2AlC MAX phase deformed without kinking and delamination, as opposed to the observations in single crystalline Ti3SiC2 films. Several possible reasons for the different deformation mechanism observed are discussed.
These results are of importance for the fundamental understanding of the origin of material characteristics, and serve as an initial study initiating further investigations of the influence of defects on MAX phase properties.
Place, publisher, year, edition, pages
2008. , 53 p.
Ti2AlC, MAX phases, nanoindentation, mechanical properties, deformation
IdentifiersURN: urn:nbn:se:liu:diva-15059ISRN: LITH-IFM-A-EX--08/2019--SEOAI: oai:DiVA.org:liu-15057DiVA: diva2:37748
2008-09-26, Röntgen, IFM, LiU, 10:15 (English)
Rosen, Johanna, Dr.Giuliani, Finn, Dr.
Hultman, Lars, Prof.