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

Abstract

The effects of alloying elements Re, Ru, Ta, Ti, and W on the activation enthalpy of dislocation cross-slip in γ′-Ni₃Al are studied combining density functional theory calculations with the classical theory of dislocations. The elements Re and W are 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.

Keywords:

• density functional theory
• dislocation mobility
• electronic structure
• plastic flow properties

Acknowledgments

This work is supported by the National Basic Research Program (‘973’ Project, Ministry of Science and Technology of China, Grant No. 2011CB606402) and the National Natural Science Foundation (Ministry of Science and Technology of China, Grant No. 51071091).