Microstructural investigation of SDM microcasting droplets

Abstract: "Our research efforts seek to improve the fundamental understanding of the deformation and solidification of metal droplets, which is applicable to Shape Deposition Manufacturing (SDM) Microcasting. Research includes direct numerical simulations of the process and a variety of experimental techniques to validate the numerical models. This report details our use of microstructural characterization as a validation technique. Individual microcasting droplets are cross-sectioned, etched and examined by optical microscope. Energy dispersive x-ray analysis (EDX) is also used to identify material composition in samples that involve dissimilar materials. Using these techniques we are able to gain a qualitative understanding of the cooling process through variations in microstructure, and quantitative estimates of both cooling rates (through dendrite arm spacing measurements) and substrate remelting (through structure change in the substrate). This information is being compared with numerical results to confirm the accuracy of our numerical models."