Axial and bending strain effects in Ag and AgNiMg/Bi-2212 wires
Abstract The effects of axial tensile and bending strains on the critical current densities of Ag and AgNiMg/Bi-2212 wires produced by the powder-in-tube method have been studied. At T = 4.2 K and B = 12 T the critical current densities of the investigated single and multicore wires exceeded 150 and 80 A mm −2 (2 μV cm −1 offset criterion), respectively. The observed degradation of the critical current density due to strain effects is irreversible and can be attributed to the formation of microcracks within the superconducting core. In the case of Ag/Bi-2212 wires the axial tensile strain values ε 0.8 leading to a 20% reduction of the critical current density at 4.2 K and 12 T are around 0.2% for both single and multicore wires with seven filaments, whereas the ε 0.8 values for AgNiMg/Bi-2212 single and multicore wires exceed 0.5 and 0.8%, respectively. The bending strain experiments reveal a reduced sensitivity to strain effects for Ag/Bi-2212 wires with a larger fraction of Ag in the conductor cross-section. Bending at elevated temperatures has been found to affect the critical current density of Ag/Bi-2212 monocore wires at lower strain levels than axial tensile strains applied at 4.2 K. The strain leading to an irreversible reduction of the critical current density seems to be determined mainly by the residual thermal strains. Finally, results of mechanical properties of the composite wires at 4.2 K are presented. The Young's modulus of the composite wires is nearly the same for the two sheath materials, whereas the yield strengths σ 0.2 are very different. For Ag and AgNiMg/Bi-2212 single core wires, the average σ 0.2 values at 4.2 K are 46 and 89 MPa, respectively.
원문보기 무료다운로드 유료다운로드
- 원문이 없습니다.
유료 다운로드의 경우 해당 사이트의 정책에 따라 신규 회원가입, 로그인, 유료 구매 등이 필요할 수 있습니다. 해당 사이트에서 발생하는 귀하의 모든 정보활동은 NDSL의 서비스 정책과 무관합니다.
NDSL에서는 해당 원문을 복사서비스하고 있습니다. 아래의 원문복사신청 또는 장바구니 담기를 통하여 원문복사서비스 이용이 가능합니다.