Growth and physical properties of epitaxial metastable Hf1 - xAlxN alloys deposited on MgO(001) by ultrahigh vacuum reactive magnetron sputtering
2007 (English)In: Surface & Coatings Technology, ISSN 0257-8972, Vol. 202, no 4-7, 809-814 p.Article in journal (Refereed) Published
Epitaxial metastable Hf1 - xAlxN alloys with 0 ≤ x ≤ 0.50 were grown on MgO(001) substrates at 600 °C by ultrahigh vacuum reactive magnetron sputtering from Hf and Al targets in 90% Ar + 10% N2 discharges at 7 mTorr. X-Ray diffraction and cross-sectional transmission electron microscopy show that Hf1 - xAlxN alloys are single crystals with the B1-NaCl structure. Rutherford backscattering spectroscopy investigations reveal that all films are slightly overstochiometric with N / (Hf + Al) = 1.05 ± 0.05. The relaxed lattice parameter decreased linearly from 0.4519 nm with x = 0 to 0.4438 nm with x = 0.50, compared to 0.4320 nm expected from the linear Vegard's rule. We find a metastable single phase field that is remarkably broad given the large lattice mismatch (≃ 9%) between the two alloy components. Alloying HfN with AlN leads to an increase in hardness (≃ 30% to 32.4 ± 0.7 GPa), as well as nanostructured compositional modulations due to the onset of spinodal decomposition. © 2007 Elsevier B.V. All rights reserved.
Place, publisher, year, edition, pages
2007. Vol. 202, no 4-7, 809-814 p.
IdentifiersURN: urn:nbn:se:liu:diva-39622DOI: 10.1016/j.surfcoat.2007.05.079Local ID: 50348OAI: oai:DiVA.org:liu-39622DiVA: diva2:260471