Neutron radiographic measurement of macrosegregation in an experimentally solidified binary metal alloy

Neutron radiography is considered as a mean of extending and improving experimental verification methods for alloy solidification models. A gallium-27 wt. pct. indium alloy is solidified in a square cavity, chilled along one vertical side wall, and macrosegregation in solidified ingots is measured using neutron radiography. Neutron radiographs are recorded on X-ray film, and since the neutron capture cross-section of indium is more than an order of magnitude larger than that of gallium, good contrast between indium enriched and depleted zones is obtained. Moreover, calibration, film processing, and digital image processing procedures are developed in order to accurately quantify the macrosegregation recorded on neutron radiographs. The method yields a highly resolved macrosegregation field, rather than a few discrete measurements, and is used to help interpret measured cooling curves and infer thermosolutal convection patterns, which existed during solidification