The role of grain-boundary disorder in the generation and growth of antiphase domains during recrystallization of cold-rolled Cu3Au

An experimental study by transmission electron microscopy was made of the morphology of the antiphase domains formed when heavily rolled Cu3Au is annealed at a temperature slightly below the critical temperature for ordering, Tc. Domains are formed at the advancing grain boundary with extremely small size and they grow as recrystallization proceeds. From an early stage, domain walls show a preference for {100} orientations. Diffraction experiments using a 1 nm probe on a scanning transmission electron microscope were conducted on a grain boundary 8.5° off the ∑3 coincident site lattice orientation. The results show that the superlattice reflection near to the boundary is markedly weaker than that away from it, suggesting the existence of an atomically disordered grain boundary zone 1–2 nm thick. A theory was constructed for the genesis and growth of domains during recrystallization, taking into account the dragging pressure which newly formed domains exert upon a moving grain boundary, thereby diminishing the effective driving pressure for grain-boundary motion; a critical domain size is estimated which should completely inhibit grain-boundary motion. The intriguing fact that no domains at all are formed during the recrystallization of strongly ordered intermetallics such as Ni3Al is discussed and a reason is proposed.