Microcrystallography and chemical microanalysis of polycrystalline Nb3Sn superconductors

Abstract

Polycrystalline Nb3Sn is a superconductor with a high superconducting temperature, 18 K. The material can withstand a high magnetic field which makes it especially useful in strong superconducting magnets for magnetically confined fusion reactors and high energy particle accelerators. Several metallurgical factors influence the superconducting properties of Nb3Sn, e.g. grain size, compositional inhomogenities and small amounts of alloying elements. We have used a 100 keV analytical electron microscope (AEM) to detect the characteristic x rays (EDS) in order to study spatial composition variations, and to locate alloying elements in the crystal unit cell using ALCHEMI (Atom Location by Channeling Enhanced Microanalysis).