Investigation on the relationship between intermediate temperature embrittlement and intergranular precipitate in Ni(Bi) alloy

Zheng L., Schlesiger R., Chellali R., Baither D., Schmitz G.

Abstract

Ni and Ni-based superalloys generally exhibit intermediate temperature embrittlement (ITE), which isusually interpreted by the evolution of intergranular precipitates. In this paper, the relationship betweenITE and intergranular precipitates was investigated in a binary Ni(Bi) alloy. The tensile ductility of Ni(Bi)alloy shows evident ITE with a maximum between 700 oC and 750 oC. The microstructure of the sampleheat treated at 750 oC was observed to be free of precipitates within grains and at grain boundaries. Theinterpretation of intergranular precipitates for ITE was then discussed and proven to be invalid.