Resistance and Thermoelectric Measurements of Cold-Worked Copper and the Resistance Minimum at Low Temperatures

Abstract

Measurements of the change of residual resistance ratio of copper as a function of the percentage reduction in cross-sectional area by cold-working in liquid helium, liquid nitrogen or at room temperature and subsequent ageing treatments show (1) the relative change of the ratio during recovery between 77°K and room temperature to that accompanying recovery and recrystallization at higher temperatures; (2) that there appears to be no recovery process taking place below 77°K; (3) that specimens cold-worked in liquid helium or nitrogen and aged at room temperature have a higher residual resistance ratio than specimens both cold-worked and aged at room temperature.