In-situ x-ray scattering study of the cubic to hexagonal transformation of AlN in Ti1-xAlxN
2014 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 73, 205-214 p.Article in journal (Refereed) Published
In the present work, we have studied the decomposition of arc evaporated Ti0.55Al0.45N and Ti0.36Al0.64N during heat treatment in vacuum by in-situ synchrotron wide angle x-ray scattering primarily to characterize the kinetics of the phase transformation of AlN from the cubic NaCl-structure to the hexagonal wurtzite-structure. In addition, in-situ small angle x-ray scattering measurements were conducted to explore details of the wavelength evolution of the spinodal decomposition, thus providing information about the critical size of the c-AlN rich domains prior to the onset of the h-AlN transformation. We report the fractional cubic to hexagonal transformation of AlN in Ti1-xAlxN as a function of time and extract activation energies between 320 and 350 kJ/mol dependent on alloy composition. The onset of the hexagonal transformation occurs at about 50 K lower temperature in Ti0.36Al0.64N compared to Ti0.55Al0.45N where the high Al content alloy also has a significantly higher transformation rate. A critical wavelength for the cubic domains of about 13 nm was observed for both alloys. Scanning transmission electron microscopy shows a c-TiN/h-AlN microstructure with a striking morphology resemblance to the c-TiN/c-AlN microstructure present prior to the hexagonal transformation.
Place, publisher, year, edition, pages
Elsevier, 2014. Vol. 73, 205-214 p.
IdentifiersURN: urn:nbn:se:liu:diva-106506DOI: 10.1016/j.actamat.2014.04.014ISI: 000337853100020OAI: oai:DiVA.org:liu-106506DiVA: diva2:716465
On the day of the defence date of the thesis the status of this article was Manuscript.2014-05-092014-05-092015-06-01Bibliographically approved