Production techniques for discontinuous filament A-15 superconductor wire.

摘要

Around 1977 several groups began to develop a new class of high performance multifilamentary superconducting composites for large scale magnets, in which the individual filaments are not continuous. The special feature of these composites is the long but discontinuous ribbon shaped filaments of Nb(sub 3)Sn or V(sub 3)Ga which are dispersed in a bronze matrix. Despite these discontinuities, critical current density is as good or better than bronze processed wire at magnetic fields up to around 12 T; the strain tolerance is higher; the ultimate tensile strength is better than the bronze wire by roughly a factor of 2. For applications where strength and strain tolerance are critical, these materials are superior; for applications where ac loss within the superconductor must be kept low or where fields above 12 T are necessary with Nb(sub 3)Sn, they are less satisfactory. In the present review, we will try to avoid duplication of details and make reference to the previous reviews where appropriate. In addition, we will present more detailed information with respect to our own work and will present information published or completed subsequent to the previous reviews. Also, the reference list presents a fairly complete listing through early spring 1983 giving the paper titles as an aid to indicate content. Throughout most of this review we will refer the processing steps to Nb(sub 3)Sn-Cu, but it should be realized that essentially identical steps apply to V(sub 3)Ga-Cu materials.