Theoretical and experimental study of photoacoustic and electron-acoustic effects in solids with internal stresses

Results of a theoretical and experimental study of photoacoustic and electron-acoustic effects in solids with internal stresses are presented. In the theoretical part, an approach to describing these effects on the basis of a generalized concept of thermoelastic energy of a solid with internal stresses and the nonlinear Murnaghan model for the elastic part of its energy is developed. The results of studying objects with internal stresses in the context of an integrated experimental approach incorporating the techniques of photodeflection and thermal-wave and photoacoustic microscopy with piezoelectric recording of the signal are reported. It is shown that a similar approach allows one to detect the arrangement of the strained surface areas of the object and to evaluate the extent to which its thermal and thermoelastic parameters are affected by internal stresses. The results of applying this approach to a study of Vickers indentations in silicon nitride ceramics are reported. (C) 2000 MAIK "Nauka/Interperiodica".