Cellular automata simulation of grain growth of powder metallurgy Ni-based superalloy

Primary gamma' phase instead of carbides and borides plays an important role in suppressing grain growth during solution at 1433 K of Ni-based FGH98 superalloys. Results illustrate that as-fabricated FGH98 superalloy has equiaxed grain structure, and after heat treatment, grains remain equiaxed but grow larger. In order to clarify the effects of the size and volume fraction of the primary gamma' phase on the grain growth during heat treatment, a 2D cellular automata (CA) model was established based on the thermal activation and the lowest energy principle. The CA results are compared with the experimental results and show a good fit with an error less than 10%. Grain growth kinetics are depicted, and simulations in real time for various sizes and volume fractions of primary gamma' particles work out well with the Zener relation. The coefficient n value which reflects the pinning ability in Zener relation is theoretically calculated, and its minimum value is 0.23 when the radius of primary gamma' phase is 2.8 gm.