Studies of Electron Beam Coevaporated Nb3Sn Composites; Critical Current and Microstructure

The critical current pinning force has been measured as a function of the magnetic field for a variety of microstructures of Nb3Sn. These include Nb3Sn structures with columnar grains, codeposited Nb3Sn-A1203structures with equiaxed grains, and codeposited Nb3Sn-Cu structures with equiaxed grains. The peak in the pinning force is compared with the grain size. For grains or columns larger than 400 X an inverse grain size dependence is found. For smaller grains the pinning force appears to decrease. A possible detrimental effect of copper on Nb3Sn is pointed out. © 1979 IEEE