Grain refinement driven by recrystallization after annealing nonequilibrium solidification microstructure of a deeply undercooled nickel alloy

Traditional recrystallization technology is based on recrystallization annealing after artificial plastic deformation. In the present study, we found that rapid solidification through deep undercooling can induce substantial plastic deformation and recrystallization. Applying cycle superheating combined with molten glass purification technologies, Ni88Cu6Co6 alloys were highly undercooled to a maximum undercooling of 300K. Microstructure characteristics and its evolution varying with bulk undercooling during the rapidly solidified process were analyzed. The grain-refined microstructure that appeared at low undercooling regimes was caused by dendrite remelting. The dominant factor of grain refinement microstructure appearing in the high-undercooling regime was recrystallization. It was found that, after annealing rapid solidification microstructure of Ni88Cu6Co6 alloy with a undercooling of 240K at 1223K for 12min, the partially recrystallized rapid solidification microstructure was further refined by recrystallization. This study has opened up a new recrystallization technology and is worthy further research.