Ultrasonic spectroscopy of metallic spheres using electromagnetic-acoustic transduction

An ultrasonic technique for studying vibrational resonant modes of metallic spheres is presented. The technique employs electromagnetic‐acoustic transduction with a configuration consisting of a sample surrounded by a coil in a static magnetic field. Resonance spectra from 0.5 to 4.5 MHz with the coil axis parallel and perpendicular to the magnetic field are measured for a 3.145‐mm‐diam sphere of polycrystalline 2024 aluminum. Elastic constants calculated from the resonant peak frequencies are consistent with results obtained using an ultrasonic pulse‐echo system. This new technique has advantages over pulse‐echo and conventional resonance techniques for experiments where high absolute accuracy is necessary or where samples are heated far above room temperature.