Recrystallization for Ni_(54.6)Pd_(45.4) Alloy under Large Degree of Undercooling
Structure evolution driven by recrystallization in the bulk undercooled Ni54.6Pd45.4 alloy was investigated by quenching the sample at different cooling stages.The results show that recrystallization of the solid beyond the critical undercooling for grain refinement starts at the end of rapid solidification,and develops during slow solidification and subsequent cooling process.At the initial stage of recrystallization,nuclei successively formed in the sample,And the grain size decrease.At the later stage,annexation of grains dominates the recrystallization process,due to which the number of grain size increases.As undercooling before solidification increases,the deformation degree in the rapidly solidified dendrite net rises,and the recalescence temperature as well as the duration at high temperature decreases.Consequently the recrystallization grain size structure decreases.