Stress-strain curves for niobium crystals deformed at temperatures below ambient

Niobium crystals, with a wide range of orientations, have been deformed at temperatures where slip takes place on the anomalous (011) plane. A strong orientation dependence of the axial yield stress was observed in both tension and compression; at 77 K the stress-strain curves were serrated. Both the yield stresses and the stress-strain curves were affected by the surface condition of the test specimens.