Abstract
Nickel aluminide is an important material for a number of applications, especially when used as a strengthening constituent in high-temperature Ni-based superalloys. Despite this, there is minimal information on its mechanical properties such as strength, plasticity, creep, fatigue, and fracture. In the present work, a first-principles based pure alias shear deformation has been applied to shed light on dislocation characteristics in using the predicted stacking fault energy (i.e., the γ surface) and ideal shear strength . Results include direct evidence for the splitting of a dislocation into two Shockley partials on the plane, which is further supported by the equivalence of the complex stacking fault (CSF) energy and the antiphase boundary (APB) energy . Estimates of the Peierls stresses using and elastic properties suggest the prevalence of edge dislocations in Ni and screw dislocations in , agreeing with experimental observations regarding the dominance of edge dislocations in the first stage of crystal deformation in fcc metals and the yield-strength anomaly related to screw dislocations in . The present calculations further point out that the CSF and APB111 are easily formed by shear due to the low-energy barriers, although the lowest planar energies are for the superlattice intrinsic stacking fault and the APB001. Through the case of , the present work demonstrates that the pure alias shear methodology is not only computationally efficient but also provides valuable insight into the nature of shear-related properties.
- Received 1 August 2019
- Revised 22 October 2019
DOI:https://doi.org/10.1103/PhysRevB.101.024102
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