Insight into the deformation behavior of niobium single crystals under uniaxial compression and tension at the nanoscale

Size-dependent deformation behavior of niobium single-crystalline samples 200–900 nm in diameter is investigated by in situ compression and tension testing. Stress–strain curves in compression show discrete plastic flow associated with dislocation escapes at the surface. In tension, plastic flow is more continuous with pronounced strain hardening, and fracture occurs at the low true strain of ∼3%. Transmission electron microscopy analysis of the same 100 nm nanopillar before and after deformation provides insights into dislocation activity during compression deformation.