Nonlinear elastic properties of the polycrystalline refractory metals at Megabar pressures: Theoretical approach

• Published in: Materials & design Vol. 139; pp. 1 - 6
• Main Authors: Krasilnikov, O.M., Lugovskoy, A.V., Vekilov, Yu.Kh, Lozovik, Yu.E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 05-02-2018
• Subjects: Ab initio; High pressure; Lamé constants; Metals; Nonlinear elasticity; Properties modeling; Properties modeling; Ab initio; Lamé constants; Nonlinear elasticity; Metals; High pressure
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2017.10.012

We present the theoretical technique for the calculation of nonlinear elastic properties of polycrystals in the presence of hydrostatic pressure. For the isotropic aggregates of single-crystal grains with cubic or hexagonal structures at given pressure we define the Lamé constants and express them through the second and third order single-crystal elastic constants. We present the calculated third order Lamé elastic modules of polycrystalline W, Mo and Ru in the pressure range of 0–600GPa. The results agree with available experimental data. The obtained values can be used for the prediction of properties for these materials at high pressures and finite deformations. We show, that the methodology can be effectively used with ab initio calculations techniques to obtain the data on elastic properties of practical importance.
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•The technique for the calculation of linear and nonlinear elastic constants of polycrystals at high pressures is proposed.•The technique was applied to practically important metals Mo, W and Ru in the pressure range of 0-600 GPa.•The new data, Lamé constants of second and third order with full account of pressure and deformation effects were obtained.