Grain refinement mechanism of rapidly solidified nickel alloys

Abstract The solidification microstructure evolution of Ni-25 at.% Cu alloys under different undercooling degrees were studied by the cladding method and cyclic superheating method. Two grain refinement phenomena observed in obtained undercooling. In low condition, dendrite remelting is main reason for recalescence process, while high stress accumulated process leads to recrystallization later stage recalescence. Under condition undercooling, structure composed complete equiaxed grains with relatively uniform size, which indicates that boundary migration occurs during growth.