Tensorial elastic properties and stability of interface states associated with Σ5(210) grain boundaries in Ni3(Al,Si)

Martin Friák; Monika Všianská; David Holec; Martin Zelený; Mojmír Šob

doi:10.1080/14686996.2017.1312519

Tensorial elastic properties and stability of interface states associated with Σ5(210) grain boundaries in Ni₃(Al,Si)

Sci Technol Adv Mater. 2017 May 2;18(1):273-282. doi: 10.1080/14686996.2017.1312519. eCollection 2017.

Authors

Martin Friák^{1

2}, Monika Všianská^{1

2}, David Holec³, Martin Zelený⁴, Mojmír Šob^{1

2

5}

Affiliations

¹ Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
² Central European Institute of Technology, CEITEC MU, Masaryk University, Brno, Czech Republic.
³ Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Leoben, Austria.
⁴ Institute of Materials Science and Engineering, NETME Centre, Faculty of Mechanical Engineering, Brno University of Technology, .
⁵ Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic.

Abstract

Grain boundaries (GBs) represent one of the most important types of defects in solids and their instability leads to catastrophic failures in materials. Grain boundaries are challenging for theoretical studies because of their distorted atomic structure. Fortunately, quantum-mechanical methods can reliably compute their properties. We calculate and analyze (tensorial) anisotropic elastic properties of periodic approximants of interface states associated with GBs in one of the most important intermetallic compounds for industrial applications, Ni₃Al, appearing in Ni-based superalloys. Focusing on the Σ5(210) GBs as a case study, we assess the mechanical stability of the corresponding interface states by checking rigorous elasticity-based Born stability criteria. The critical elastic constant is found three-/five-fold softer contributing thus to the reduction of the mechanical stability of Ni₃Al polycrystals (experiments show their GB-related failure). The tensorial elasto-chemical complexity of interface states associated with the studied GBs exemplifies itself in high sensitivity of elastic constants to the GB composition. As another example we study the impact caused by Si atoms segregating into the atomic layers close to the GB and substituting Al atoms. If wisely exploited, our study paves the way towards solute-controlled design of GB-related interface states with controlled stability and/or tensorial properties.

Keywords: Ab initio calculations; elasticity; grain boundaries; segregation.

Grants and funding

This research was supported by the Academy of Sciences of the Czech Republic through the Fellowship of J. E. Purkyně (M.F.); the Ministry of Education, Youth and Sports of the Czech Republic [projects CEITEC 2020 (LQ1601) (M.F., M.Š. and M.V.), NETME CENTRE PLUS (LO1202) (M.Z.)] as well as by the Czech Science Foundation [projects GA 14-22490S (M.F., M.Š.), GA 16-24711S (M.V.)]. Computational resources were supplied by the Ministry of Education, Youth and Sports of the Czech Republic under the Projects CESNET [project number LM2015042], CERIT-Scientific Cloud [project number LM2015085], and IT4Innovations National Supercomputer Center [project number LM2015070] provided under the program Projects of Large Research, Development and Innovations Infrastructures.