Enhancement of the critical current of multifilamentary Nb/sub 3/Sn conductors by tensile stress
The critical current I/sub c/ and the strain epsilon within multifilamentary Nb/sub 3/Sn conductors subjected to a uniaxial tensile stress were measured. I/sub c/ increases with increasing epsilon and passes through a maximum I/sub c m/ at a strain epsilon/sub m/. The ratio I/sub c m//I/sub c/ is a function of epsilon-epsilon/sub m/ only and independent of conductor type. As the ratio ..gamma.. of the cross-sectional area of the conductor taken up by Nb/sub 3/Sn to that of bronze decreases, epsilon/sub m/ increases. For ..gamma..=0.06, the smallest value used, epsilon/sub m/=0.9% and I/sub c m//I/sub c/sub 0/=1.4 at 4.4 T (I/sub c/sub 0/: initial value of I/sub c/). This effect occurs because the coefficient of thermal expansion is greater for bronze than for Nb/sub 3/Sn. The resulting pressure to which the Nb/sub 3/Sn is subjected at 4.2 K reduces I/sub c/. Initially, an externally applied axial stress reduces the pressure upon the Nb/sub 3/Sn and produces an increase in I/sub c/. Further increase of the stress exerts a resultant tensile stress upon the Nb/sub 3/Sn and brings about a reduction in I/sub c/. The technical applicability of the conductor is improved by the internal compressive stress since less degradation in I/sub c/ occurs at high tensile loads when compared to the case of a stress-free conductor.
- Research Organization:
- Research Laboratories, Siemens AG, D-8520 Erlangen, Federal Republic of Germany
- OSTI ID:
- 7099072
- Journal Information:
- J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 48:9; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Tensile strain / transverse compressive stress effects in Nb{sub 3}Sn multifilamentary wires with CuNb reinforcing stabilizer
Influence of tensile stresses on the superconducting temperature of multifilamentary Nb/sub 3/Sn composite conductors
Related Subjects
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
CRITICAL CURRENT
CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
FILAMENTS
NIOBIUM ALLOYS
NIOBIUM BASE ALLOYS
PHYSICAL PROPERTIES
PRESSURE DEPENDENCE
STRAINS
STRESSES
SUPERCONDUCTIVITY
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TIN ALLOYS
TRANSITION TEMPERATURE
TYPE-II SUPERCONDUCTORS