Effect of WN content on toughness enhancement in V1–xWxN/MgO(001) thin films
2014 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 32, no 3, 030603- p.Article in journal (Refereed) Published
The authors report the growth and mechanical properties of epitaxial B1 NaCl-structure V1-xWxN/MgO(001) thin films with 0 ≤ x ≤ 0.60. The Gibbs free energy of mixing, calculated using density functional theory (DFT), reveals that cubic V1-xWxN solid solutions with 0 ≤ x ≤ 0.7 are stable against spinodal decomposition and separation into the equilibrium cubic-VN and hexagonal-WN binary phases. The authors show experimentally that alloying VN with WN leads to a monotonic increase in relaxed lattice parameters, enhanced nanoindentation hardnesses, and reduced elastic moduli. Calculated V1-xWxN lattice parameters and elastic moduli (obtained from calculated C11, C12, and C44 elastic constants) are in good agreement with experimental results. The observed increase in alloy hardness, with a corresponding decrease in the elastic modulus at higher x values, combined with DFT-calculated decreases in shear to bulk moduli ratios, and increased Cauchy pressures (C12–C44) with increasing x reveal a trend toward increased toughness.
Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. Vol. 32, no 3, 030603- p.
IdentifiersURN: urn:nbn:se:liu:diva-106347DOI: 10.1116/1.4867610ISI: 000335965300003OAI: oai:DiVA.org:liu-106347DiVA: diva2:715531