Impact of defects induced by Re on screw dislocation cross-slip in Ni3Al

Abstract:

The anomalous flow behavior of Ni3Alat high temperature is closely related to the cross-slip of super-partial dislocations. Using a first-principles calculation, an impact of Re-effect on dislocation slip mediated creeps in the Ni3Al is investigated. The analysis of energy factors associated with the formation enthalpy of point defects reveals Re prefers to occupy Al sites, and the Re-Re pair prefers to occupy Al-Al sites in γ′-Ni3Al phase. By calculating the generalized stacking fault energies for and systems in Ni3Al, it is found that the Re occupying Al sites can promote the cross-slip of screw dislocations. A longitudinal arrangement of and defects should be able to effectively impede the nucleation and movement of dislocations compared with their horizontal layout. As their interaction is characterized and assessed by a correlation energy function between and point defects, a weak correlation is demonstrated to be favorable for the improvement of the anomalous flow of γ′ phases at high temperature. Re atoms preferentially occupy Al sites for the improvement of yield strengths of Ni3Al can be attributed to a weak repulsive interaction between and defects.