J. Phys. IV France 110 (2003) 153
Observation of the shear failure mode in nanostructured titanium under quasistatic uniaxial compression at 300-4.2 KE. D. Tabachnikova1, V. Z. Bengus1, K. Csach2, J. Miskuf2, V. V. Stotyarov3 and R. Z. Valiev3
1 Institute for Low Temperature Physics & Engineering, ASU, Lenin's Ave., Kharkov 61103, Ukraine
2 Institute of Experimental Physics, SAS, Watsonova 47, Kosice 04353, Slovakia
3 Ufa State Aviation Technical University, Ufa 450000, Russia
Nanostructured Ti (100 -300 nm average grain size), processed by severe plastic deformation through equal channel angular pressing of commercially pure Ti rods after quasi-static compression (at 0.0004 s -1strain-rate) of prismatic (2 2 7mm) samples has at low temperatures (77 and 4,2K) yield stresses two times larger than the initial CP-Ti, failure stresses ranging from 1.4 to 2.4 GPa. The shear failure phenomenon has been observed at 77 and 4,2K. Nanostructured Ti is absolutely thermomechanically unstable against catastrophic plastic shear under low temperature straining. The catastrophic plastic shear spreads through the whole section of the sample with a velocity close to the transverse sound velocity and has a dynamical character. It is supposed that the micro mechanism of the shear failure of nanostructured Ti consists in extending of the catastrophic shear by grain boundary dislocations.
© EDP Sciences 2003