Internal friction and physicomechanical properties of solids

Different aspects of applying the physical acoustics methods (in particular, internal friction method) in mechanics, optics, and radiation solid-state physics are considered. The results of acoustic experiments in situ upon plastic deformation and under the irradiation of crystals by high-energy (8 MeV) protons are discussed. The acoustic technique for studying the microplasticity of solids in a wide range of vibrational stress amplitudes is described. An example of studying the acoustooptic interactions in the defect structure of a wide-gap HgI2 semiconductor crystal is shown. The possibility of using acoustic measurements for investigating the mechanisms of brittle-ductile transition in bcc alloys is discussed.