This proposal seeks to elucidate the coarsening effects in miscibility-gap alloy solidification owing to thin-film effects. The NSF funding sought will support the experimental phase of a joint experimental/analytical investigation where the analytical part is being supported by NASA. In the experimental study, the directional solidification of the succinonitrile-camphene system via video imaging through a transparent cell utilizing a gradient stage microscope facility will be done. This will provide important information on the repulsion and capture of ultra-fine particles and droplets by advancing solidification fronts. Utilizing a Rame-Hart pendant drop apparatus, component interfacial tensions will be measured. The data obtained will be used to validate the analytical model being developed under NASA funding. In particular, validation will hinge on predictions of the critical droplet size with measurements of the largest droplets rejected by the advancing solidification front determined from the video imaging data. This work will provide the first experimental data for droplet rejection in directional solidification. All prior studies involved solid particle rejection.
