Special quasirandom structure method in application for advanced properties of alloys: A study on Ti0.5Al0.5N and TiN/Ti0.5Al0.5N multilayer

  • Tasnádi, Ferenc
  • Wang, Fei
  • Odén, Magnus
  • Abrikosov, Igor A.
Abstract:
Abstract The special quasirandom structure (SQS) approach is a successful technique for modelling of alloys, however it breaks inherently the point symmetry of the underlying crystal lattice. We demonstrate that monocrystalline and polycrystalline elastic moduli can scatter significantly depending on the chosen \{SQS\} model and even on the supercell orientation in space. Also, we demonstrate that local disturbances, such as vacancies or interfaces change the \{SQS\} configuration in a way, that significantly affects the values of the calculated physical properties. Moreover, the diversity of local environments in random alloys results in a large variation of the calculated local properties. We underline that improperly chosen, generated or handled \{SQS\} may result in erroneous theoretical findings. The challenges of the \{SQS\} method are discussed using bulk Ti0.5Al0.5N alloy and TiN/Ti0.5Al0.5N multilayer as model systems. We present methodological corrections for the mindful application of this approach in studies of advanced properties of alloys.
Year:
2015
Type of Publication:
Article
Keywords:
Modelling alloys
Journal:
Computational Materials Science
Volume:
103
Pages:
194 - 199
ISSN:
0927-0256
DOI:
http://dx.doi.org/10.1016/j.commatsci.2015.03.030