Homogenizing effects of Co on multi-scale elemental distribution in Ru-containing Ni-based single crystal superalloys

The effects of Co on multi-scale elemental distributions were studied in an advanced Ru-containing Ni-based single crystal superalloys. Two types scales of microstructural heterogeneities, the large-scale dendritic segre-gations and small-scale elemental partitions between gamma/gamma' phase were compared in as-cast, heat-treated and thermal-exposed alloys. The elemental homogeneities on both large and small scale were shown to be enhanced with Co additions, giving rise to the restricted precipitation of TCP phase. It is thus expected the potential role of Co to replace part of Ru in advanced superalloys.