In Situ Tomographic Observation of Dendritic Growth in Mg/Al Matrix Composites

Understanding the interaction of nano/micro-particles with evolving microstructures during solidification is critical for developing new materials with improved mechanical properties through either particulate reinforcement and/or via microstructural refinement. In this study, we investigate the influence of nanoparticles on the evolving dendrites in both Mg and Al based metal matrix composites via in situ synchrotron tomography. Ultrasonic treatment was applied during the raw material preparation to break the particle agglomeration. The solidification of primary dendrites was characterized and quantified. The results reveal the underlying physical mechanisms that enable nanoparticles to modify the grain size in both alloy systems. These insights into dendrite evolution help both to inform and validate numerical models of the solidification microstructures of metal matrix composites.