Influence of Lattice Scattering on Mathiessen's Rule in Dilute Binary Magnesium Alloys

Abstract

Measurements and analysis of resistivity as a function of temperature are presented for dilute magnesium alloys with solutes Al, Ag, Li, and Cd over the temperature range 4.2-372\ifmmode^\circ\else\textdegree\fi{}K. It is found that previously observed negative deviations from Mathiessen's rule occurring in these alloys can be accounted for by considering the change in Gr\"uneisen $\ensuremath{\theta}$ on alloying and, in fact, a reduced resistivity $\frac{\ensuremath{\rho}}{{\ensuremath{\rho}}_{\ensuremath{\theta}}}$ is found to have the same dependence on reduced temperature $\frac{T}{\ensuremath{\theta}}$ as pure Mg for all of the nontransition metal alloys studied. Based on the above observation, an empirical method is presented for analyzing the temperature-resistivity characteristic of magnesium alloys containing transition-metal-induced low-temperature resistivity anomalies. This spin term in the resistivity is found to occur at much higher temperatures than previously thought and above the temperature of magnetic ordering varies logarithmically with temperature. The magnitude of the anomaly is found to vary linearly with transition-metal concentration. Both of these findings are in agreement with recent theoretical studies.