The Velocity of Ultrasonic Wave in Liquid Tin, Lead and Zinc

The velocity of ultrasonic waves in liquid tin, lead and zinc has been measured in the temperature range from the melting points to the temperatures about 300 K higher than the melting points by using the double transducer pulse method at 2 MHz. The relation between the velocity of ultrasonic waves and the experimental temperature could be represented by a straight line having a negative temperature coefficient over the entire range of experimental temperatures for these liquid metals. The adiabatic and isothermal compressibilities were calculated at their melting points from the obtained results and other thermodynamic data. In comparison of the isothermal compressibility calculated by simple models with the experimental one, it was shown that the result by Ascarelli’s model was in good agreement with the experimental value but a hard sphere model did not yield any satisfactory result for these liquid metals. From these results, it was concluded that the contribution of free electron gas to the compressibility of these liquid metals cannot be neglected.