Ultrasonic velocity and attenuation of nano‐scaled copper measured by laser ultrasonic technique.

The velocity and attenuation of an ultrasonic longitudinal wave for nano‐scaled copper are determined by a laser ultrasonic technique. The nano‐scaled copper samples are composed of super fine particles 10‐nm in size, and are prepared by a suppressing and sintering technique under a vacuum, and different pressures are used in the experiment. These samples are of thicknesses between 125–300 μm. The experimental results show that the velocity dispersions and attenuation spectra of nano‐scaled copper depend on their fabrication technology conditions, which are different from those of conventional Cu. The attenuation of nano‐scaled copper is proportional to the frequency of ultrasound, and some absorption peaks appear at the curves of attenuation versus frequency, but the attenuation of conventional Cu is proportional to the square of the frequency. The velocity of nano‐scaled copper is lower than that of conventional Cu. The experimental system, measurement method, results, analyses and discussions are also ...