A theoretical calculation of stacking fault energy of Ni alloys: The effects of temperature and composition

Combining cluster expansion (CE) method with one dimensional axial Ising model, this work investigated the effects of alloying elements and configurational variations due to temperature on the stacking fault energy (SFE) of FCC Ni binary alloys. Ensembles of large numbers of atomistic structures, each with more than similar to 400 atoms, were generated to consider sufficient long-range chemical disorder and temperature effects due to configurational entropy. A Monte Carlo Metropolis algorithm was used to generate these structures, whose energies were then evaluated based on the effective cluster interactions obtained from CE. As a baseline, this work had shown the SFE of pure Ni and Al to be 127 mJ/m(2) and 137 mJ/m(2), respectively, which agreed with the experimental values of 125 mJ/m(2) and 150 mJ/m(2) reported in the literature. Additions of Al, Ti, Cr and Co to pure Ni were found to decrease the SFE to different extents. Although temperature does not strongly influence the SFE of the FCC Ni-Al and Ni-Cr binary alloys, it can lead to significant changes to the SFE of the FCC Ni-Ti and Ni-Co alloys. While effects of temperature and composition on SFE observed in this work were calculated from binary Ni alloys, the general trends are nonetheless expected to be valid in the gamma phase of multicomponent Ni superalloys.

Automated summary

By combining CE method with one dimensional axial Ising model, this study explored the impacts of alloying elements and temperature on the stacking fault energy (SFE) of FCC Ni binary alloys. The findings show that temperature and composition have varying effects on SFE, with potential implications for multicomponent Ni superalloys in the gamma phase.