Effect of the cooling rate on microstructure and hardness of MAR-M247 Ni-based superalloy

► Casting process of MAR-M247 was reproduced in Gleeble thermo-mechanical simulator. ► The cooling rates were precisely controlled in the range of 0.25-10 K/s. ► Constituent phases, their morphology and size varied with cooling rates. ► Dendrite spacing decreased and microhardness increased with increasing cooling rate.