Microstructure and microtexture evolution of undercooled Ni-15%Cu alloy

Rapid solidification of undercooled Ni-15%Cu (mole fraction) alloy was studied using glass fluxing and cyclic superheating. To show the effect of cooling history on the microstructure and microtexture evolution, the as-solidified samples were either cooled naturally or quenched into water after recalescence. At low undercooling, grain-refined microstructure has a random texture and a highly oriented texture without annealing twins for the case of naturally cooling and quenching, respectively. At high undercooling, a fully random texture as well as a number of annealing twins are observed, and recrystallization and grain growth independently happen on the cooling history. Fluid flow and recrystallization play an important role in the microtexture formation for grain refinement at both low and high undercooling.