Twin growth and its interaction with precipitates

New models for twin growth and its interaction with precipitate in Inconel-718 are proposed in this paper. The measured accumulated XRD intensities to represent the quantity of the Ni3Nb(δ) phase are in agreement with its dissolution in twin/grain interior and precipitation again in twin/grain boundary. Present result shows that twin growth is associated with and similar to a “wave front” movement of twin boundary mainly resulting from the assistance of sufficient vacancies and solute atoms from dissolved Ni3Nb(δ) phase diffusing from the twin interior toward the twin boundary to build up the existed twin. This leads to the overall free energy reduction and results in twin growth. Furthermore, possible interaction of twin growth meeting NbC particle is also discussed.