Laser Photoacoustic Microscopy of Vickers Indentations in Titanium

The images of Vickers indentations in titanium are obtained by photoacoustic microscopy with piezoelectric-signal detection. It is shown that the analysis of the photoacoustic-image features makes it possible to obtain information on the nature of internal stresses in metal. In the framework of the single-temperature model of material thermoelasticity, it is demonstrated that the detected changes in the structure of photoacoustic images may be caused by the dependence of the thermal-expansion coefficient on stresses and by the presence of stress concentrators within the indentation.