Effect of minor carbon additions on the high-temperature creep behavior of a single-crystal nickel-based superalloy

•Creep behaviors of alloys with different amounts of carbon were investigated.•The creep rupture lives increased and later decreased with more carbon.•Second-phase particles were responsible for the different creep behaviors.

Different amounts of carbon were added to a single-crystal nickel-based superalloy. The microstructural evolution of these alloys before and after high-temperature creep tests was investigated by employing scanning electron microscopy and transmission electron microscopy. Upon increasing the carbon contents, the volume fraction and diameter of the carbides increased gradually: however, the creep lives of the alloys increased slightly at first and subsequently decreased. The formation of second-phase particles, such as the nano-sized M23C6, blocky and needle-shaped μ phase, was observed in the creep samples, which was closely related to the high-temperature creep behaviors.