Characterisation of single crystal Ta with respect to strain rate

Results will be presented from compression experiments on single crystal tantalum in lattice orientations [100], [110], [111] and [-149] across a wide range of strain rates between 10^-3 s^-1 and 10⁴ s^-1. Experiments utilised a screw driven load frame and minimised split Hopkinson pressure bar, complementing previous data obtained via gas gun plate impact. All orientations demonstrated a Strain Rate Sensitivity (SRS) with log-linear variation in the flow stress with respect to the strain rate between 10^-3 and 10³ s^-1 and a sharp increase in the SRS near 10⁴ s^-1 except [110]. Large variations in flow stress between the various orientations was also observed. Post-shock characterisation of recovered plate impact loaded samples between 6 and 23 GPa will also be presented. Micro-pillar compression tests were utilised in combination with scanning electron microscope (SEM) imaging to the determine Schmid factor slip systems present and the critical resolved shear stress across the different crystal orientations. The extent to which the micro-pillar data relates to differences seen between the crystal orientations in prior shock loading velocimetry and uniaxial stress compression tests will be discussed. © Crown Owned Copyright 2022/AWE.