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Materials 2010, 3(3), 1573-1592; doi:10.3390/ma3031573

Influence of Yttrium on the Thermal Stability of Ti-Al-N Thin Films

, 2
, 2
 and 1,*
Received: 5 January 2010; in revised form: 18 February 2010 / Accepted: 3 March 2010 / Published: 4 March 2010
(This article belongs to the Special Issue Advances in Materials Science)
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Abstract: Ti1-xAlxN coated tools are commonly used in high-speed machining, where the cutting edge of an end-mill or insert is exposed to temperatures up to 1100 °C. Here, we investigate the effect of Yttrium addition on the thermal stability of Ti1-xAlxN coatings. Reactive DC magnetron sputtering of powder metallurgically prepared Ti0.50Al0.50, Ti0.49Al0.49Y0.02, and Ti0.46Al0.46Y0.08 targets result in the formation of single-phase cubic (c) Ti0.45Al0.55N, binary cubic/wurtzite c/w-Ti0.41Al0.57Y0.02N and singe-phase w-Ti0.38Al0.54Y0.08N coatings. Using pulsed DC reactive magnetron sputtering for the Ti0.49Al0.49Y0.02 target allows preparing single-phase c-Ti0.46Al0.52Y0.02N coatings. By employing thermal analyses in combination with X-ray diffraction and transmission electron microscopy investigations of as deposited and annealed (in He atmosphere) samples, we revealed that Y effectively retards the decomposition of the Ti1-x-yAlxYyN solid-solution to higher temperatures and promotes the precipitation of c-TiN, c-YN, and w-AlN. Due to their different microstructure and morphology already in the as deposited state, the hardness of the coatings decreases from ~35 to 22 GPa with increasing Y-content and increasing wurtzite phase fraction. Highest peak hardness of ~38 GPa is obtained for the Y-free c-Ti0.45Al0.55N coating after annealing at Ta = 950 °C, due to spinodal decomposition. After annealing above 1000 °C the highest hardness is obtained for the 2 mol % YN containing c-Ti0.46Al0.52Y0.02N coating with ~29 and 28 GPa for Ta = 1150 and 1200 °C, respectively.
Keywords: TiAlN; Yttrium; thermal stability; decomposition TiAlN; Yttrium; thermal stability; decomposition
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Moser, M.; Kiener, D.; Scheu, C.; Mayrhofer, P.H. Influence of Yttrium on the Thermal Stability of Ti-Al-N Thin Films. Materials 2010, 3, 1573-1592.

AMA Style

Moser M, Kiener D, Scheu C, Mayrhofer PH. Influence of Yttrium on the Thermal Stability of Ti-Al-N Thin Films. Materials. 2010; 3(3):1573-1592.

Chicago/Turabian Style

Moser, Martin; Kiener, Daniel; Scheu, Christina; Mayrhofer, Paul H. 2010. "Influence of Yttrium on the Thermal Stability of Ti-Al-N Thin Films." Materials 3, no. 3: 1573-1592.

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