LASER DIAGNOSTICS OF ACOUSTIC EMISSION DURING FORMATION OF NEW PHASES IN SOLIDS

摘要

The acoustic emission of an ensemble of growing germs of a new phase in elastic medium, the scattering of hypersonic wave by an indicated ensemble and the transition processes initiated by an acoustic pulse were investigated. Two characteristic stages of germ formation-initial and late (stage of coalescention) were considered. The analysis of acoustic emission showed, that the ensemble of growing germs generates acoustic waves which frequencies ω_E are simple connected with the size R of heterogeneities (germs), and the intensity of each spectral component is determined by their concentration n(R). If we direct a laser beam on the sample, the radiation will be dispersed on the hypersonic waves, and the scattering angle will be simple connected the frequency of an acoustic wave and therefore with the sizes of a germ R.