Solidification behavior of Ni-based superalloy at different cooling rates

The solidification behavior of Ni-based superalloy in the cooling rates range of 0.5-10 degrees C/s was investigated for simulation the casting process. Scheil model was used to calculate the solidification path of Ni-based superalloy. The results show that the precipitation sequence of solid phases from the liquid phase was as follows: Liquid (L)-> L+gamma -> L+gamma+MC ->gamma+MC+gamma/gamma eutectic. The precipitation temperature of gamma/gamma eutectic was increased with the increase of cooling rate. The solidification structures of Ni-based superalloy were found to be mainly dendritic, and the distance between dendrites decreased with the increase of cooling rate. The MC carbides enriched with C, Ti, Hf, Ta, and other elements presented rectangles, which contributed to refine the solidification structure as the heterogeneous nucleus. The nano-indentation was used to measure the gamma+gamma ' matrix and MC cabides, and the mechanism of cooling rate on the evolution of microstructure during the solidification was discussed.