Novel particulate reinforced tin for tubular Nb3Sn multifilamentary superconductors

A novel technique is under development for the production of a tubular core Nb₃Sn composite superconductor using an inexpensive, easily fabricated core material. Initial experiments on the tin rich core material have included several different combinations of pure Sn, pure Cu, Sn4 wt%Cu, Sn8 wt%Cu, SiO₂, and Al₂O₃ blended powders, which were hydrostatically compacted, and then consolidated by room temperature angular extrusion. The resulting consolidates are characterized by density, hardness, metallography, and compression testing. Of the mixtures tested, the best core material is a blend of rapidly solidified Sn8 wt%Cu powder plus 6.9 weight percent nanosized SiO₂ particles. This particulate reinforced tin has a flow stress of (124 MPa)18 ksi and sufficient ductility to be conventionally extruded through a reduction ratio of four. A stronger tin alloy core material should be possible by powder metallurgy processing improvements.