Effect of alloying element on dislocation cross-slip in γ′-Ni3Al: a first-principles study

The effects of alloying elements Re, Ru, Ta, Ti, and W on the activation enthalpy of dislocation cross-slip in gamma'-Ni3Al are studied combining density functional theory calculations with the classical theory of dislocations. The elements Re and Ware found to effectively increase planar fault energies on the (111) plane and decrease the cross-slip activation enthalpy in Ni3Al. The reduction of activation enthalpy will increase the probabilities of cross-slipping and forming sessile dislocation locks. Therefore, Re and W can inhibit the further motion of dislocations and raise the flow stress of Ni3Al in the anomalous temperature regime. The underlying electronic mechanism is the strong bonding of Re-Ni and W-Ni and the weak bonding of Re-Al and W-Al in fault areas.