Determination of elastic constants of generally anisotropic inclined lamellar structure using line-focus acoustic microscopy.

A methodology for measuring elastic constants of different phases in materials with lamellar microstructure by line-focus acoustic microscopy is developed. The material microstructure investigated is modeled by generally anisotropic multilayers arbitrarily inclined to the sample surface on which acoustic microscopy measurements are performed. To calculate surface acoustic wave (SAW) propagation in such structures quasi-static effective elastic constants are determined and compared with calculated frequency-dependent constants. As a model material, practically important, Ti-6Al-2Sn-4Zr-2Mo alloy is selected. Time-resolved line-focus acoustic microscopy experiments are performed on a Ti-6242 alpha/beta single colony (Ti-6Al-2Sn-4Zr-2Mo alloy) and on a Ti-6Al alpha-phase single crystal for which elastic constants of different phases are determined using inversion of measured SAW velocities. To validate the experimental methodology, SAW velocities in an X-cut quartz crystal are measured as a function of sample orientation angle and compared with predictions based on the known elastic moduli of quartz.