Importance

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Abstract

The sheath (3) is a material, which includes an aluminium (Al) matrix, in which nanometric aluminium oxide particles (Al₂O₃) are homogenously dispersed, the content of Al₂O₃ is 0.25 to 5 vol. % and the balance is Al. It is preferred that Al₂O₃ originates from the surface layer present on Al powder used as feedstock material for consolidation. The superconductor based on magnesium diboride (MgB₂) core (1) is fabricated by powder-in-tube or internal magnesium diffusion to boron technology, while the tube is the Al+Al₂O₃ composite, which is a product of powder metallurgy. A loose Al powder is pressed by cold isostatic pressing, and then the powder billet is degassed at elevated temperature and under vacuum, and then is hot extruded into a tube. A thin diffusion barrier (2) tube filled up with a mixture of Mg and B powders or Mg wire surrounded with B powder is placed into the Al+Al₂O₃ composite tube under inert gas or vacuum. Such composite unit is cold worked into a thin wire and then annealed at 625-655° C. for 8-90 min, what results in a formation superconducting MgB₂ in a wire's core (1).

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First Claim