The Electrical Resistivity of Copper-Zinc and Copper-Tin Alloys at Low Temperatures

A systematic investigation of the resistivity $\rho$ of the copper-zinc and copper-tin alpha-phase solid solution systems has been made in the temperature range 14.3°K to room temperature. Measurements were taken on both annealed and hard-drawn specimens. For the annealed set, the resistivity varied linearly with the temperature above 70°K and with a higher power of $T$ at low temperatures, approaching a constant value below 20°K. Above 70°K the value of ($\frac{d\rho }{\mathrm{dT}}$) was found to increase linearly with atomic percent solute in variance with Matthiessen's rule. The residual resistivity increased with percent of added solute for both alloy systems, but not in agreement with Nordheim's theory, unless it be assumed that the effective number of free electrons per atom increases with added solute atoms or that the specimens were not true random solid solutions. The cold work produced some unexpected effects. Although the expected increase of resistivity with residual strain occurred in the Cu-Zn alloys, the specimens of zero to three atomic percent tin, which were hard-drawn through a 75 percent reduction and left in the strained state, showed a lower resistivity at low temperatures than did the corresponding annealed, quenched specimens. Possible explanations of this anomolous behavior are discussed.