About the nonlinear acoustic parameter during deformation of AMG61 alloy

Abstract

Various acoustic effects are used in the study of deformation processes. Acoustic emission is most often mentioned in such studies, and the effects due to nonlinear properties of a deformable metal are the subject of the present work. These properties of real solids lead to nonlinear acoustic effects of the interaction elastic waves forbidden by the theory of elasticity of a homogeneous isotropic body. The work solves the problem of using the principles of nonlinear acoustics in studying the deformation of AMg61 alloy samples. A surface elastic wave is used to control the alloy condition. The process of the elastic wave propagation in the deformed AMg61 alloy due to nonlinear effects is accompanied by generating the double frequency, both of the longitudinal component of the wave and the shear one, the latter is forbidden by equations of the classical elasticity theory. Excitation and reception in the samples was carried out by piezoelectric converters (PES). A wedge converter with a resonance frequency of 1MHz was used to excite the surfactant. The passing surfactant was recorded by a wedge converter with a resonance frequency of 2 MHz. We justified the control technique of the nonlinear acoustic parameter with respect to amplitudes of the first and second harmonics measured during the whole deformation process. An experimental device has been developed to control the nonlinear acoustic parameter in the process of changing the structural state of the sample metal. The pilot study results of the nonlinear acoustic parameter under Amg61 alloy deformation are given. It is shown that the nonlinear acoustic parameter, as well as the acoustic emission activity, is sensitive to changing mechanisms of the defective structure evolution. The non-linearity jump formation during deformation of alloy AMg61 is recorded, which may indicate adjustment of the metal structure. The presented data demonstrate the increase of acoustic nonlinearity in metal at various deformation stages, both at early stages of elastoplastic deformation and at pre-destruction stage, which can be used as the prognostic criterion.