Abstract
The effects of applied elastic stress on the temperature dependence of ultrasonic velocity has been investigated in commercial aluminum and copper. Velocities of 10-MHz longitudinal and shear waves as a function of temperature were measured when specimens of these metals were subjected to external compressive stresses applied in a plane perpendicular to the direction of propagation. In all measurements, the velocity increased linearly as the temperature was lowered in the range between 280 and 200 K. The slopes of the linear relationships of the longitudinal velocities were found to decrease linearly as the amount of stress was increased within the elastic limit of the specimen. The maximum decrease in the temperature dependences of the longitudinal velocities of aluminum and copper were, respectively, 23 and 6%. These occurred at applied stresses of 96 and 180 MPa. The temperature dependence of the shear velocity in aluminum, however, remained unchanged with the application of stress.