Impact of nitrogen vacancies on the high temperature behavior of (Ti1-xAlx)N-y alloys
2016 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 119, 218-228 p.Article in journal (Refereed) Published
Substoichiometric solid solution alloys of cubic (Ti1-xAlx)N-y with x = 0.26, 0.48 and 0.60, and y ranging from 0.93 to 0.75 were grown by cathodic arc deposition. The influence of nitrogen deficiency on their thermal stability was studied by X-ray diffractometry, differential scanning calorimetry, scanning electron microscopy, and atom probe tomography. The nitrogen deficiency did not significantly affect the columnar growth nor the as deposited hardness. At elevated temperatures, alloys with x = 0.48 and 0.60 decompose isostructurally into cubic c-TiN and cubic c-AlN domains, which is consistent with spinodal decomposition. The decomposition is retarded by decreasing the nitrogen content, e.g. the formed isostructural domains in (Ti0.52Al0.48)N-0.92 at 900 degrees C are similar in size to (Ti0.52Al0.48)N-0.75 at 1200 degrees C. The formation of hexagonal w-AlN is shifted to higher temperatures by decreasing nitrogen content. Nucleation and growth of Al-Ti clusters in a Ti rich matrix were observed for the alloys with high Ti content, x = 0.26. These results suggest that nitrogen deficiency reduces the driving force for phase separation. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD , 2016. Vol. 119, 218-228 p.
TiAlN system; Nitrogen vacancies; Spinodal decomposition; Atom probe tomography; Thin films
Metallurgy and Metallic Materials
IdentifiersURN: urn:nbn:se:liu:diva-132334DOI: 10.1016/j.actamat.2016.08.024ISI: 000384778300021OAI: oai:DiVA.org:liu-132334DiVA: diva2:1046208
Funding Agencies|Erasmus Mundus doctoral program DocMASE; Swedish Research Council VR [621-2012-4401]; Swedish Foundation for Strategic Research, SSF via MultiFilms program [RMA08-0069]; Swedish government strategic research area grant AFM - SFO MatLiU [2009-00971]; VIN-NOVA (M - Era.net) [2013-02355(MC2)]; DFG; federal state government of Saarland [INST 256/298-1 FUGG]; AME-Lab (European Regional Development Fund) [C/4-EFRE-13/2009/Br]2016-11-122016-11-012016-11-12