Fatigue Property Examinations of Conductors for Pulsed Magnets

Cu matrix composites are used as conductors for pulsed magnets that have potential to reach 100 T. The conductors are fabricated by cold drawing that introduces high densities of dislocations or interfaces and internal stress. The density of the dislocation and the interface affects the mechanical properties of the conductors, such as the tensile strength and fatigue endurance at 77 K of the composites. Understanding the performance of the conductors under cyclic loading, i.e. fatigue properties, helps one to make good use of them for pulsed magnets and to manufacture conductors to meet the requirements of the magnets, particularly when the magnetic stress reaches the limit of the mechanical strength of the conductors. The goal of this research is to understand the fatigue properties of a Cu-0.085wt%Ag conductor and to relate such properties to mechanical tensile strength, dislocation densities and interface structures. The fatigue test loading is either in stress-controlled or strain-controlled mode. This work sheds a new light on the correlation between the tensile and fatigue properties at 77 K by consideration of dislocation densities and precipitate in particle strengthened conductors.