Theoretical strength of solids: recent results and applications

We present the results of recent achievements in the field of atomistic evaluation of the theoretical (ideal) strength of solids with emphasis on the ab initio approaches to the synthesis of the theoretical and experimental data. It is shown that the characteristics of fracture toughness (brittleness) of polycrystals are partially inherited from their (perfect) lattices. On the other hand, the response of perfect metallic crystals to triaxial tension in terms of the ultimate strain is qualitatively different from the response typical of the engineering materials. This can be attributed to the plasticity-driven growth and coalescence of microvoids at particles of the secondary phase under triaxial tension. The values of theoretical shear strength computed by using ab initio and/or MD methods are close to the experimental data.