Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. IV France 06 (1996) C8-849-C8-852
Ultrasonic Resonance of Metallic Spheres at Elevated TemperaturesW. Johnson
Materials Reliability Division, National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80303, U.S.A.
A unique ultrasonic system has been constructed for measuring resonant frequencies and damping of metallic spheres at elevated temperatures. This system employs electromagnetic-acoustic transduction, with a solenoid coil surrounding the sphere in a uniform magnetic field. Temperature is measured with an optical pyrometer. Since the acoustic and temperature measurements are noncontacting, the uncertainties associated with external damping are relatively small. The resonant frequency and Q of the sample are determined by digital analysis of the ring-down following a single driving tone-burst. High-temperature measurements on pure polycrystalline aluminum are presented.
© EDP Sciences 1996