Carbide Evolution of a Directionally Solidified Ni-Based Superalloy during Long-Term Exposure

Abstract

Directionally solidified Ni-based superalloy DZ483 is a kind of potential material for the blade of an advanced heavy duty gas turbine, which has good combination properties. The carbide degradation behaviors of DZ483 alloy during long-term thermal exposures were investigated at different conditions in this paper. The results show that during the long-term exposure, primary carbide will decompose in the form of MC + γ → M23C6 + γ'. Carbide on the grain boundary could be decomposed more easily than intragranular carbide. With the increase of aging time, decomposition could be observed more obviously, carbides on the grain boundary become bigger and the morphology of carbide near the grain boundary tends to be more complex. The fine dispersive particles of M23C6 on the grain boundary will grow up gradually to a thin consecutive chain of carbide with the increase of aging time.