Electrical resistivity of stretched and twisted 99.70% pure silver

Samples of anneald pure silver (99·70 wt.%) have been subjected to tensile and/or twisting deformations at room temperature. It has been found that the electrical resistivity () of the stretched silver samples decreases monotonically with the increase of tensile stress. Negative values are obtained for the stress coefficient of resistivity (SCR) both in the elastic and plastic regions, contrary to the twisted samples where positive values are obtained. The resistivity () increases almost linearly with the number of twist turns in the case of unidirectional mode of twist, whereas in the case of the bidirectional one, () increases non-linearly with the number of reversed twist turns. In such case, () obeys a function of exponential type. Moreover, the accompanying axial strain for the bidirectional mode of twist is found to be larger than that for the unidirectional one by approximately one order of magnitude.The authors would like to express their deep thanks to Prof. Dr. H. H. Hassan, Physics Department, Faculty of Science, Cairo Univ., for his critical comments and suggestions.