Strain Resistivity at 4.2 K in Pure Aluminum
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Strain induced resistivity increases are examined in pure aluminum under conditions of uniaxial tensile and compressive stress at 4. 2 K. Metal studied has an annealed residual resistivity ratio (RRR equals rho //2//7//3//K/ rho //4//. //2//K) covering the range 150-7100, is in some cases work hardened prior to testing, and is strained to levels below 10%. Resistivity is monitored during strain by eddy current coils located directly over strain gages bonded to centimeter diameter specimens. We find strain-resistivity to be slightly dependent on purity and similar for tension and compression. For all cases the empirical expression DELTA rho equals A ( epsilon //p)**B holds for plastic strains ( epsilon //p) above about 0. 1% where A and B are constants. Values of B group around 1. 5 for annealed metal and decrease to near 1. 15 for the work hardened cases examined.