Certain compositions of iron-chromium-nickel stainless steels solidify from an undercooled melt in a 2-step process. In this 2-step process, or double recalescence, the alloy first forms a metastable ferrite phase, and then transforms to a stable austenite phase. Using computational fluid dynamics modeling, Alaina is determining whether convective flow in the undercooled liquid causes mechanical deformation to the growing microstructures, called dendrites, during the metastable phase growth, and if this deformation could be the cause of the secondary solidification.
Solid dendrites in a nickel-based superalloy.
Flow simulation showing stress imparted on the fluid by the dendrite. All units are in Pascals. Creeping flow, Re=0.01.