Precipitation, planar defects and dislocations in alloys: Simulations on Ni

We present simulations of the formation of Ni3Si precipitates using a combination of molecular dynamics (MD) and the Metropolis Monte Carlo (MMC) method. Applying this technique to a Ni-Si solid solution in Cu matrix leads to Ni3Si precipitates with L12 structure as observed in experiments. Since L12 structured precipitates are most relevant for precipitation strengthening of several alloys, we focus on planar defects and dislocations in Ni3Si and Ni3Al. Ab initio calculations of the generalised stacking fault energies of Ni3Si presented in our previous work [S. Hocker, H. Lipp, E. Eisfeld, S. Schmauder, J. Roth, J. Chem. Phys. 149, 024701 (2018)] revealed that the complex stacking fault is not stable and the inflection point as well as the minimum corresponding to the antiphase boundary is shifted. In this study it is shown that this behaviour can be understood from the analysis of charge densities. Furthermore, the consequences on dislocations in Ni3Si and Ni3Al are discussed and interactions of edge dislocations with Ni3Si and Ni3Al precipitates are simulated