抄録
Recent developments on fabrication techniques of the in-situ processed multifilamentary Nb3Sn conductors are reviewed. This process is one of possible methods which can be used to minimize the problems associated with the bronze process. The technical possibility of the in-situ process was first shown by Tsuei, who used Cu-Nb or Cu-Nb-Sn alloys which were subsequently drawn to wires. Thereafter, many investigations have been carried out on the development of the fabrication techniques, and the improvement on the superconducting properties of the in-situ processed conductors. Recently, large Cu-Nb ingots with high homogeneity have been successfully cast by consumable electrode arc-melting at Ames laboratory, and this casting technique offers a prospect of the in-situ processed conductor for practical applications. Furthermore, several types of in-situ processed multistrand wires have been fabricated by means of the internal tin diffusion method.
In this paper the melting and casting techniques of Cu-Nb ingot and its transformation into multifilamentary Nb3Sn conductors are discussed in terms of the morphology and drawability of the ingots. In addition, the characteristic features of superconducting properties of the in-situ processed conductors are presented with the evidence of a strong dependence of the superconducting critical current, flux-pinning and electromagnetic coupling on the microgeometry in the conductors.
