Atomistic Simulations of Compression Tests on γ-Precipitate Containing Ni₃Al Nanocubes

The influence of \(\gamma \) precipitates on the deformation behavior of \(\gamma '\) Ni\(_{3}\)Al nanocubes with {100} side surfaces is investigated by molecular dynamics simulations of uniaxial compression tests at 300 K. The plastic deformation of the nanocubes is caused by the nucleation of Shockley partial dislocations near the cube corners followed by the formation of pseudo-twins. While the dominant deformation mechanisms and the flow stress are not affected by the presence of \(\gamma \) precipitates, the precipitates reduce the yield stress by up to 10 pct and determine the location of dislocation nucleation. These findings can be rationalized by accounting for the misfit stresses caused by the presence of the \(\gamma \) precipitates. Within the simulated ranges, the results are independent of cube size, rounding of the cube or precipitate corners, surface roughness, and strain rate. The observed precipitate softening in the dislocation-nucleation-controlled deformation of \(\gamma '\) Ni\(_{3}\)Al nanocubes is in stark contrast to the strengthening effect caused by the presence of a \(\gamma \) phase in the \(\gamma '\) precipitates in the microstructure of typical Ni- and Co-based superalloys.