Mechanism of grain refinement and coarsening in undercooled Ni–Fe alloy

Abstract

The microstructural evolution of undercooled Ni-1 at.% Fe alloy was investigated by means of fluxing and cyclic superheating. Within the achieved undercoolings, there were two grain refinement processes and agrain coarsening process.T he evolution mechanisms of the microstructure were studied applyingthe calculation of astress accumulation model and dimensionless superheating. The first grain refinementc an be ascribed to the dendrite break-up or ripening induced by remelting. The second one was caused by recrystallization induced by stress accumulation originating from the rapid solidification.