A study of ultrasonic velocities and internal friction has been carried out in Pb-Bi alloys in the concentration range of 0 to 49.5 atomic % Bi using the composite oscillator technique. From the velocity and density data a set of elastic constants namely, Young’s modulus, rigidity modulus, bulk modulus and Poisson’s ratio are estimated. The results are interpreted in terms of the phase changes occurring in the alloy system. Internal friction is found to be more sensitive than the elastic constants to the phase changes.

Ultrasonic velocities, elastic constants and internal friction are studied in Sn-In alloys in the concentration range of 0 to 30 wt% of In using composite oscillator technique. Anomalies observed in the vicinity of the phase transitions of these alloys at fourteen concentrations are interpreted in the light of the phase changes in the phase diagram.