Defects Associated with Solidification of Melt-Processed Superalloys for the Aerospace Industry

Abstract : Our Materials Engineering for Affordable New Systems (MEANS) program was centered on developing an integrated computational framework for predicting the conditions under which turbine blades can be produced that are free of deleterious solidification defects. We studied the solidification process over length scales from subnanometer to millimeter and produced a theory for defect formation. Close interaction with industry was necessary to ensure the resulting computational model will be in a form that is usable in their efforts to design new alloys and processing routes. Given the broad research focus of the project the MEANS team was composed of engineers and scientists from government laboratories, industry, and universities and is diverse in its research expertise. Our accomplishments include: Accurate prediction of liquid metal densities using ab initio molecular dynamics, development of a criterion for the stability of flows in mushy zones with heat loss, measurement of permeability of mushes using three-dimensional reconstructions, and measurement of the composition of the liquid and solid phases in mushy zones.