Energy loss, anisotropy, magnetoresistivity and recovery in aluminum strained at 4.2 K

High purity aluminum is often considered and sometimes used as the stabilizing material for practical composite superconductors. Such material has a residual resistivity ratio (
RRR = \partial273
K/
\partial4.2
K) in the range 1000 - 5000 when fully annealed. An understanding of how the RRR will change during conductor use is necessary for optimum system design. We have investigated the effects of cyclic plastic strain at 4.2K and annealing to room temperature on the RRR and magnetoresistance of aluminum covering a wide purity range. Measurements of mechanical hysteresis energy loss, anisotropic resistivity and strain induced magnetoresistance are reported. We describe selected experiments and discuss the implications of results on conductor operation.