The Distribution of Secondary- Phase Precipitates During Creep of Alloy 617

Inconel 617 is a nickel-based superalloy commonly selected for its high strength and oxidation resistance, particularly at high temperatures. Carbides may increase creep strength by inhibiting grain boundary motion; however, during creep the carbides dissolve and re-precipitate on boundaries in tension. In order to quantify the distribution of the carbides, electron backscatter diffraction and energy dispersive spectroscopy were used to analyze the microstructure. Analysis was done to determine the location of carbides (e.g., in the grains or on grain boundaries), grain boundary character, and precipitate type (i.e., Cr- or Mo-rich). We find that the major factor in carbide distribution is the character of the grain boundaries. In addition, both Mo- and Cr-rich carbides precipitate at grain boundary triple junctions with two special boundaries (i.e., J2 junctions). If the role of grain boundary character on redistribution can be determined, materials could be engineered to have microstructures resistant to carbide redistribution