Decomposition and phase transformation in TiCrAlN thin coatings
2012 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 30, no 6Article in journal (Refereed) Published
Phase transformations and mechanisms that yield enhanced high temperature mechanical properties of metastable solid solutions of cubic (c)-(TixCryAlz)N coatings are discussed in this paper. Coatings grown by reactive arc evaporation technique with metal composition range y<17 at. % and 45<z<62 at. % are studied and compared with the parent TiAlN material system. The coatings exhibit age hardening up to 1000 ºC which is higher compared to what is observed for TiAlN. In addition, the coatings show a less pronounced hardness decrease when hexagonal (h)-AlN is formed compared to TiAlN. The improved thermal stability is discussed in terms of a lowered coherency stress and a lowered enthalpy of mixing due to the addition of Cr, which results in improved functionality in the working temperature range of 850-1000 ºC of for example cutting tools. Upon annealing up to 1400 ºC the coatings decompose into c-TiN, bcc-Cr and h-AlN. The decomposition takes place via several intermediate phases, c-CrAlN, c-TiCrN and hexagonal (β)-Cr2N. The microstructure evolution investigated at different stages of spinodal decomposition and phase transformation is correlated to the thermal response and mechanical hardness of the coatings.
Place, publisher, year, edition, pages
American Vacuum Society , 2012. Vol. 30, no 6
IdentifiersURN: urn:nbn:se:liu:diva-80179DOI: 10.1116/1.4757953OAI: oai:DiVA.org:liu-80179DiVA: diva2:546051
On the day of the defence day the status of this article was: Manuscript2012-08-222012-08-222014-09-18Bibliographically approved