Influence of grain size distribution type on statistical moments of ultrasonic attenuations and phase velocities in random polycrystals.

This study investigates the sensitivity of ultrasonic phase velocity and attenuation statistics to grain size distribution types, specifically monomodal and bimodal, in cubic finite-sized polycrystals with identical overall arithmetic or volumetric grain size statistics. A large ensemble of synthetic polycrystalline microstructures was generated, and their ultrasonic responses were computed using a modified spectral function method. The latter enables estimation of both effective phase velocities and attenuation coefficients while rigorously accounting for finite specimen dimensions and statistical variabilities across different samples.