Effect of Plastic Deformation on the Electrical Resistivity of Chromium

Abstract

THE presence of a transition in the electrical resistivity and temperature coefficient of resistance of chromium in the region of 40° C. has been reported by several investigators¹. In studying the influence of plastic deformation (at 150° C.) on high-purity chromium an anomaly has been found, in that below the transition temperature the deformed material had a lower resistivity than the annealed. Curves of resistivity versus temperature are shown in Fig. 1, together with the respective temperature coefficients of resistance. No hysteresis was observed in these measurements. A positive deviation in the temperature coefficient of resistance of the deformed material is observed both below and above the transition temperature. A minimum in the curve of resistivity versus temperature for the annealed material (Fig. 1) occurs at 41° C. and is in close agreement with other workers. Particulars of the specimen material are recorded in Table 1. As shown in Fig. 2, a change in the sign occurs, from negative to positive, in the value of Δρ (the difference in resistivity between the deformed and the annealed material) on increasing temperature through the transition region, namely, −40° C. to + 40° C.