Numerical and experimental analysis of ultrasonic scattering in two-phase polycrystalline materials

Abstract

Many polycrystalline materials found in nature and used in industry consist of multiple phases. Careful nondestructive characterization of these materials is of fundamental importance for quality assurance because microstructure is strongly correlated with mechanical performance. A fundamental understanding of ultrasonic scattering from idealized two-phase materials would provide essential information regarding the predictive nature of scattering measurements to quantify such microstructures. For this purpose, samples were created using spark plasma sintering (SPS) from mixtures with different ratios (with respect to mass) of copper and iron powders. These samples were used for measurements of wave velocity, attenuation, and backscatter. Prior ultrasonic scattering models for continuous media were modified for discrete synthetic two-phase three-dimensional microstructures. In this way, the ultrasonic scattering responses were determined numerically using DREAM. 3D based on 30 realizations of synthetic microstructures representative of each volume fraction. In this presentation, the computational approach is described, and the results are then compared with the microstructures and ultrasonic data from the samples made from the binary mixtures. The results show some agreement as well as highlight some limitations of the computational model. Finally, prospects for more complex materials are discussed. [Research supported by the Air Force Research Laboratory (AFRL) under prime contract FA8650-15-D-5231.]