Strength and elastic deformation of natural and synthetic diamond crystals shock compressed along [100] J.A series of magnesium single crystals, from 0.2 to 3 mm thick, were shock loaded in directions parallel and perpendicular to the c-axis of the hexagonal closed packed (hcp) structure and at 45 to the c-axis. Shock compression along the c-axis is associated with the largest Hugoniot elastic limit (HEL) for this material. Microscopic observation of recovered c-cut samples demonstrated intense twinning with a greater density of twins near the impact surface. The low-energy basal slip was activated by shock loading along the inclined direction and has the smallest HEL. In all cases, we observe the decay of the elastic precursor wave and growth of the HEL with increasing temperature. For the inclined shock compression after the HEL, two plastic waves were found where the stress level of the first plastic wave depends on the peak shock stress. Finally, the largest spall strength was along the transversal direction and the smallest in the off-axis direction. The fracture surface of the sample of transversal orientation contains numerous groves oriented along the base planes of the crystals. V C 2014 AIP Publishing LLC. [http://dx.

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Specimens with V and U shaped notches made of austenitic high nitrogen corrosion resistant 05Kh20G10N3AMF steel are subjected to impact tests in the temperature range from +20 to -196°C, and stress-strain diagrams are recorded. The test data are used to estimate impact toughness KCV and KCU, dynamic fracture toughness J id at the stage of crack nucleation, and crack propagation energy A p . The microrelief of the fracture surfaces is studied. As compared to forging, quenching from 1100°C is found to increase the impact toughness and the dynamic cracking resistance of the steel during impact loading and to decrease the ductile-brittle transition temperature. The steel is shown to exhibit the cold brittleness behavior characteristic of bcc materials. A model is proposed for the formation of cleavage facets in austenitic steels. It is based on easy slip along lattice planes under the low shear stress at a notch tip and the development of fracture at a stress lower than the yield strength of the material.

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