Abstract
The electrical resistivities of nickel‐rich nickel‐niobium solid solutions have been determined from liquid‐helium temperatures to 1000°K. The Matthiessen rule is not obeyed at any temperature. The addition of niobium to nickel increases its ideal electrical resistivity when the alloy is in the ferromagnetic state but decreases it in the paramagnetic region. Dissolved niobium in nickel at liquid‐helium temperatures causes considerably larger perturbation for the conduction electron transport than either copper or palladium.