Ultrasonic scattering predictions of two-phase polycrystalline materials based on digital microstructures

Abstract

Many materials found in nature and used in industry consist of multiple phases, and the mechanical performance of such materials is controlled by their material organization. Ultrasonic scattering is one approach to characterize these microstructures nondestructively. In this presentation, previous ultrasonic scattering theories for two-phase materials are discussed and implemented using discrete synthetic three-dimensional microstructures as a means to assess the material statistics. These models predict the ultrasonic wave speed, attenuation, and diffuse ultrasonic backscatter with respect to the volume fraction and grain size distribution of each constituent. The computational approach is then focused on predictions for samples created using spark plasma sintering (SPS) of Cu and Fe powders with varying volume fractions as well as pure Cu and pure Fe samples. DREAM.3D is used to generate digital synthetics representative of the SPS samples as characterized using electron backscatter diffraction (EBSD). A set of 30 realizations for each volume fraction is used for each to quantify the statistical variations expected. The combined theoretical and computational model is used to study the dependence of ultrasonic wave propagation on the material organization for these two-phase materials. [Work supported by Air Force Research Laboratory (AFRL) under prime contract FA8650-15-D-5231.]