Explicit model for ultrasonic attenuation in equiaxial hexagonal polycrystalline materials

Attenuation coefficients for longitudinal and transverse ultrasonic waves are obtained in explicit form for untextured hexagonal polycrystalline materials. The equations obtained are easy to use for interpretation and evaluation of experimental results for ultrasonic characterization of microstructures. The attenuation coefficients are separated into two terms, corresponding to incident wave scattering into longitudinal and transverse waves. It is shown that the general expressions for attenuation coefficients in the long wavelength (Rayleigh) and short wavelength (stochastic) regimes transit to the known classical asymptotics. Simple equations to estimate the frequency range of the transition from the Rayleigh to stochastic regimes are also given. An example of experimental measurements in Ti alloy is provided to illustrate application of the model; the results show reasonable agreement between the experiment and the model with no adjustable parameters.