Thermomechanical Behavior of the HL-LHC 11 Tesla Nb3Sn Magnet Coil Constituents during Reaction Heat Treatment

The knowledge of the temperature induced changes of the superconductor volume, and of the thermo-mechanical behaviour of the different coil and tooling materials is required for predicting the coil geometry and the stress distribution in the coil after the Nb3Sn reaction heat treatment. In the present study we have measured the Young's and shear moduli of the HL-LHC 11 T Nb3Sn dipole magnet coil and reaction tool constituents during in situ heat cycles with the dynamic resonance method. The thermal expansion behaviours of the coil components and of a free standing Nb3Sn wire were compared based on dilation experiments.Comment: 6 pages, 12 figures, presented at MT25 conferenc

Hardness and Tensile Strength of Multifilamentary Metal-matrix Composite Superconductors for the Large Hadron Collider (LHC)

Conventional indentation hardness measurements to obtain load independent Vickers hardness values for the different phases in multifilamentary superconducting (SC) wires are described. The concept of composite hardness is validated for a binary metal-matrix metal-filament Nb-Ti/Cu composite wire. The tensile materials properties of the individual wire components are estimated from their indentation hardness. The potential and limitations of this approach are critically discussed, based on a comparison with tensile test results obtained for wires and extracted Nb-Ti filaments

Tensile Properties of the Individual Phases in Unreacted Multifilament Nb3_{3}Sn Wires

The room temperature elastic and plastic properties under uniaxial tensile loading of the different phases of an un-reacted, internal-tin process, Nb$_{3}$Sn wire have been determined by tensile tests of whole wires and of extracted Ta, Nb and Nb alloy filaments, as well as by indentation hardness measurements in metallographic wire cross sections

Sphaeroguss als Werkstoff fuer Behaelter zur Befoerderung, Zwischen- und Endlagerung radioaktiver Stoffe. Untersuchung zu alternativen Eignungsnachweisen Zusammenfassender Abschlussbericht 1989-1992

The project was intended to further enlarge the pool of safe data giving proof of the suitability and qualification of the GGG-40 nodular cast iron to serve as a material for transport and storage casks for radioactive materials, and to present these data ready for acceptance by international standards. Preparatory work achieved a harmonization of methods and criteria applied for testing that have been adopted by the IAEA. The fracture safe design of the CASTOR VHLW prototype cask made of nodular cast iron has been proven for extreme load conditions. Tests for brittle fracture sensitivity of the material revealed good resistance of the material even in the area of the yield strength point and with artificial crack-type flaws at this spot. The cask stood the 14 m-drop test onto two hard objects and the resulting, extraordinary bending strain. Accompanying materials tests enhanced the information on the connection between chemical composition of the microstructure and the mechanical strength of the nodular cast iron. The tests included various casting methods (sand casting, die casting) in the manufacturing process, and the effects of transformation processes in the microstructure as a result of thermal treatment. The statistical evaluation of single test results within the framework of quality assurance tests for the qualification of transport and storage casks for radioactive materials has been supported by mechanical and fracture-mechanical analyses in 24 samples of nodular cast iron. (orig./HP)Entsprechend der Zielsetzung des Vorhabens stand die weitere Etablierung des Werkstoffes Sphaeroguss (GGG-40) im Bereich der Transport- und Lagerbehaelter fuer radioaktive Stoffe im internationelen Rahmen im Vordergrund. Es gelang eine weitgehende fachliche Uebereinstimmung hinsichtlich der Bewertungsmethoden und -kriterien zu erzielen und auf IAEA-Ebene zu etablieren. Die ausserordentliche Belastbarkeit eines Prototypbehaelters aus Sphaeroguss (CASTOR VHLW) konnte unter extremen Beanspruchungssituationen nachgewiesen werden. So war selbst bei Spannungen im Bereich der Material-Streckgrenze und vorhandenem rissartigen Fehler an dieser Stelle keine Sproedbruchneigung des Werkstoffes erkennbar. Den entsprechenden 14 m-Fall auf zwei harte Widerlager mit daraus folgender hoher Biegebeanspruchung ueberstand der Behaelter unbeschadet. Mittels begleitender Werkstoffuntersuchungen wurde die Kenntnisse ueber die Zusammenhaenge zwischen der chemischen Zusammensetzung der Gefuegeausbildung und den mechanischen Eigenschaften von Sphaeroguss erweitert. Dabei wurden unterschiedliche Giessverfahren (Sand- und Kokillenguss) in der Herstellung und die Auswirkungen von Umwandlungsprozessen im Gefuege infolge von Waermebehandlungen diskutiert. Die statistische Auswertung von Einzelergebnissen im Rahmen der Qualitaetssicherung bei der Begutachtung von Transport- und Lagerbehaeltern fuer radioaktive Stoffe wurden durch mechanische und bruchmechanische Untersuchungen an 24 Werkstoffen aus Gusseisen mit Kugelgraphit ergaenzt. (orig./HP)SIGLEAvailable from TIB Hannover: F94B877+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Temperature induced degradation of Nb-Ti/Cu composite superconductors

The degradation mechanisms of state-of-the-art Nb-Ti/Cu superconductors are described, based on in-situ synchrotron X-ray diffraction measurements during heat treatment. A quantitative description of the Nb-Ti/Cu degradation in terms of critical current density, Cu stabiliser resistivity and mechanical composite strength is presented. In an applied magnetic field a significant critical current degradation is already observed after a 5-minute 400 °C heat treatment, due to variations of á -Ti precipitate size and distribution within the Nb-Ti alloy filaments. A strong degradation of the strand mechanical properties is observed after several minutes heating above 550 °C, which is also the temperature at which the formation of Cu-Ti intermetallic phases is detected. Several minutes heating at 250 °C are sufficient to increase the RRR of the strongly cold work strands inside a Rutherford type cable from about 80 to about 240. Heating for several minutes at 400 °C does not cause a significant conductor degradation in self-field and, thus, leaves enough temperature margin for the electrical interconnection of Nb-Ti/Cu conductors with common low temperature solder

Tensile properties of the individual phases in superconducting multifilament Nb3Sn wires

International audienc