Plasticity of lead alloy single crystals in the superconducting and normal states at 4.2 K

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Abstract
The flow stress increment ΔSN associated with a transition superconducting-normal has been studied for a number of lead-thallium, -tin, -bismuth, -cadmium single crystals at 4.2 K as a function of solute concentration, deformation, and strain rate. Increasing solute concentrations cause an increase of ΔτSN at the beginning of the deformation, and the stress dependence of ΔτSN is also strongly affected by solute atoms. At small solute concentrations, ΔτSN was found to increase along the deformation curve in a similar way as in pure lead. At higher solute concentrations ΔτSN decreases as the applied stress increases. The dislocation inertial model recently proposed by Granato for the enhanced plasticity of the superconducting state is discussed with respect to solid solution effects. If it is assumed that electronic drag remains the predominant dissipative mechanism for alloys, the model can explain all the observed effects at least qualitatively.