Effect of solidification parameters on the microstructures and properties of CMSX-10

A single master heat of CMSX-10, a third generation, single crystal Ni-base superalloy was processed with withdrawal rates between 5 and 35 cm/h. The as-cast microstructures and solidification partitioning ratios were characterized as a function of the withdrawal rate and used to verify the thermal gradient during processing. As expected, the primary and secondary dendrite arm spacing decreased with increasing withdrawal rate. Significant differences in the phase transformation temperatures were observed in DTA testing due to the withdrawal rates used to process the samples. After heat treatment, transformation temperatures, microstructures and tensile and creep properties were determined. Once heat-treated, the solidus, liquidus and γ′-solvus temperatures did not appear to be a function of withdrawal rate. Similarly, mechanical testing of heat-treated samples also indicated that the tensile and creep properties were not a function of the withdrawal rate.