Enhancement of Critical Current Densities by the Prebending Strain at Room Temperature for Nb3Sn Wires

概要

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The influence of a repeated bending strain at room temperature on the critical current densitiy of bronze route Nb3Sn wires was investigated. We found that the critical current $I_{\text{c}}$ is significantly increased by applying a repeated bending load (pre-bending treatment) at room temperature. The maximum enhancement of $I_{\text{c}}$ was approximately twice at 16 T for CuNb-reinforced Nb3Sn wires by a 0.5% prebending strain and the critical current density $J_{\text{c}}$ became about 528 A/mm2 at 4.2 K and 16 T. A comparison of the stress dependent $I_{\text{c}}$ values obtained before and after applying prebending treatments for CuNb/Nb3Sn wires indicates that not only the stress dependence of $I_{\text{c}}$ but also the maximum $I_{\text{c}}$ at the axial strain-free state are improved. The improvement of the stress dependent $I_{\text{c}}$ is in agreement with the prediction made based on the calculation using the uniaxial stress/strain distribution model. Moreover, the increase in the maximum $I_{\text{c}}$ may be related to the release of stress/strain states along the radial direction through prebending treatments.
Japan Society of Applied Physicsの論文
2003-10-01