Ultrasonic Absorption in Liquid Sodium—Potassium Alloys

Abstract
Ultrasonic absorption measurements were made in sodium—potassium alloys at temperatures from 20° (or mp) to 150°C. The measured absorption was found to be higher than the classical absorption. In liquid sodium the bulk viscosity is attributed to structural relaxation and the ratio of bulk/shear viscosity is 3. In the alloys, in addition to structural relaxation, a second relaxation loss was observed at temperatures below 80°C. This loss was greatest for an alloy of composition near 33 at.% of K, and is attributed to the slow adjustment of the equilibrium 2Na+K⇌Na2K.
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