The effects of γ' on the migration of grain boundary or recrystallization front and the change in γ' morphology in both recrystallized and unrecrystallized regions have been investigated in partially recrystallized Ni-Base Superalloy; Ni-24Co-4Al-4Ti-5Cr-5Mo (wt%) alloy (designated as Alloy M) of very small lattice misfit between the precipitate, γ' and the matrix, γ'. When Alloy M specimens homozenized for 1 hour at 1200℃ are aged for 30 min and 15 hours at 1100℃, precipitation of γ' occurs, the shape of γ' remaining sphere. A cellular appearing recrystallization product formed by annealing a cold worked Alloy M at 1100℃ has been studied by electron microssopy. The strain free recrystallization cells consist of very large rodular γ' particle in γ' matrix. The γ' precipitate is oriented and coherent both before and after recrystallization. In the system having small γ', the migration of grain boundary or recrystallization front is easier than that in the system having large γ'. This is contrary to the case of systems having incoherent percipitates or dispersoids such as nitride, oxide, etc.
The transition from elliptical to irregular shape in morphology of γ' occurs in unrecrystallized region in partially recrystallized Alloy M. This is a clear observation of recrystallization in γ', confirmed by scanning and transmission electron microscopy.
When a recrystallized region meets another recrystallized region, the migrating interface between recrystallized regions interacts with coarse γ' in the different ways from the case of one between recrystallized and deformed regions.
The interface between recrystallized regions cuts through large γ' particles, both matrix and γ' having changed orientations.
