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

The effect of cooling rate on the microstructure of MAR-M247 Ni-based superalloy was investigated via physical simulation of the casting process. Solidification experiments with cooling rates in the range of 025-10 K/s showed smooth temperature profiles with measured cooling rates matching the set values. The MAR-M247 showed cellular (0.25 K/s) and dendritic (1, 5 and 10 K/s) microstructures. Microconstituents also varied with cooling rates: gamma/gamma' matrix with carbides and gamma/gamma' eutectic at 025 K/s, gamma/gamma' matrix with carbides at 1 K/s. and gamma/gamma' matrix with carbides and gamma/MC eutectic at 5 and 10 K/s. Moreover, the secondary dendritic arm spacing decreased and the hardness increased with the increase in the cooling rates. (C) 2012 Elsevier B.V. All rights reserved.