The role of orientation on the shock response of single crystal tantalum
J. C. F. Millett, Philip Avraam, G. Whiteman, David J. Chapman, S. Case
Abstract
The response of single crystalline tantalum to one-dimensional shock loading has been investigated as a function of crystalline orientation to the loading axis. Results show that this has a significant effect, particularly on the Hugoniot elastic limit (HEL). [100] and [111] HELs are near identical with the [110] HEL having the lowest strength. This is contrary to predictions obtained by applying the Schmid factor analysis, where the ordering was expected to be (highest strength first) [111], [110], with the [100] orientation being the softest. Adopting a more appropriate model based on uniaxial strain conditions, as was previously done successfully for FCC aluminum and copper, did not rationalize our observations. We show that a non-Schmid effective stress model, incorporating twinning/anti-twinning asymmetry, has much greater success in reproducing the experimental relative HELs magnitudes. Using this model, we make a quantitative estimation of the magnitude of non-Schmid effects and compare these to equivalent low temperature, quasi-static estimates from the literature.