Appropriate conditions to obtain single-crystal (SX) castings of the nickel-based superalloy CM186LC, developed for directional solidification, are investigated. Cylindrical samples with starter blocks and grain selectors are cast via a proprietary SX Bridgman process. The effect of the solidification rates (V) ranging from 1 to 10 mm⋅min−1 on the microstructure is explored. Primary dendrite arm spacings (λp) fall within the expected range of 200–500 μm. Single crystal is achieved at V ≅ 3 mm⋅min−1. The growth direction of the crystals in all cases diverges strongly from 001 orientation. Different solidification behavior of CM186LC compared to otherwise chemically similar CMSX-4 is attributed to minor additions of grain boundary strengtheners C, Hf, B, and Zr.
Baldissera et al. (2025) studied this question.