Jean-Francois Croteau¹, Eureka Pai Kulyadi², Chaitanya Kale³, Di Kang², Derek Siu⁴, Thomas R. Bieler², Philip Eisenlohr², Kiran Solanki³, Elisa Cantergiani¹, Nicolas Jacques⁵, Daniel Balint⁴, Paul Hooper⁴, Said Atieh⁶; ¹I-Cube Research, ²Michigan State University, ³Arizona State University, ⁴Imperial College, ⁵ENSTA Bretagne, ⁶CERN

An investigation of the mechanical properties of differently oriented high-purity niobium single crystals deformed in tension at strain rates between 10^-4 to 10³ s^-1 is presented. Specimens were cut from a large grain niobium disk used for the manufacturing of SRF cavities. The strain rate sensitivity and the associated activation volume are presented for a specific orientation. Different crystallographic tension directions exhibit significantly different softening and hardening behaviors and elongation at fracture. Such anisotropy is reduced at high strain rates. The effect of early necking, adiabatic heating and the activation of multiple slip systems on the tensile split Hopkinson results is discussed. An attempt is made to explain the differences in flow stress based on crystal orientation evolution during deformation.