Manufacturing technique of Nb3A1 super-conductive sheet by electrically heated powder rolling

The conventional manufacturing processes of superconductive wires or sheets an complex. Nb3Al is a well-known superconductive material. Nb3Al could be produced from powder directly by an advanced powder rolling technique. The experimental apparatus is composed of a powder rolling mill within a vacuum chamber and a direct current power supply unit. Powder is supplied into the roll gap and heated by applying electricity during rolling. The method is called 'electrically heated powder rolling'. Nb-25.4Al (mol%) powder of which particle size was under 0.15 mm was prepared by plasma melt gas atomizing (PMGA) technique. The powder consists of super-saturated solid solution of Nb and Al. But after electrically heated powder rolling, the existence of Nb3Al (A15) phase was confirmed by X-ray diffraction. The sheet was porous and the thickness was about 0.7 mm. The sheet was re-rolled to the thickness of about 0.5 mm, then pore of the sheet was eliminated. The resistivity of the re-rolled sheet was measured at lower temperature than RT and Tc-(0) of 15 K was confirmed. It is believed that electrically heated powder rolling is effective manufacturing technique for superconductive sheet such as intermetallic compounds. (C) 1999 Elsevier Science B.V. All rights reserved.