Electronic origin of structure and mechanical properties in Y and Nb alloyed Ti-Al-N thin films
2011 (English)In: International Journal of Materials Research - Zeitschrift für Metallkunde, ISSN 1862-5282, Vol. 102, no 6, 735-742 p.Article in journal (Refereed) Published
Ti(1-x)A(x)N thin films are industrially well established protective coatings, whose beneficial mechanical properties are mainly based on the formation of a metastable microstructure and local composition during film synthesis. Alloying of a transition metal (TM) to Ti(1-x)Al(x)N is a promising approach to reach yet higher oxidation and corrosion resistance in high-temperature environments, while maintaining a high intrinsic hardness and elasticity, being essential for a good wear performance. In order to study the effect of alloying with Y and Nb on the structure and mechanical properties of the industrially preferred cubic (c) Ti(1-x)Al(x)N system, quaternary Ti(1-x-z)Al(x)Y(z)N and Ti(1-x)Al(x)Nb(z)N films were deposited by means of plasma-assisted reactive magnetron sputtering and investigated using X-ray diffraction, transmission electron microscopy and nanoindentation. It is shown that Y addition to c-Ti(0.42)Al(0.58)N changes its structure towards single phase wurtzite (w) Ti(0.36)Al(0.55)Y(0.09)N, with deteriorated mechanical properties. In contrast, by the addition of Nb the structure remains cubic up to the studied composition of c-Ti(0.35)Al(0.57)Nb(0.08)N and the film hardness increases from 30.1 to 39.5 GPa. Ab initio studies show that the effect of Y and Nb alloying on structure and mechanical properties of quaternary Ti(1-x-z)Al(x)TM(z)N is not only correlated with strain increase due to lattice mismatch, but rather the changed electronic configuration.
Place, publisher, year, edition, pages
Hanser , 2011. Vol. 102, no 6, 735-742 p.
Ti-Al-N; Ti-Al-Y-N; Ti-Al-Nb-N; Ab initio; Electronic structure
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-69868DOI: 10.3139/146.110520ISI: 000292525800018OAI: oai:DiVA.org:liu-69868DiVA: diva2:433341