Effects of the triple junction types on the grain boundary carbide precipitation in a nickel-based superalloy, a statistical analysis

The morphology evolution of carbide precipitated on grain boundary nearby different triple junctions in grain boundary engineering (GBE) treated nickel-based Inconel Alloy 690 aged at 715 degrees C for different time was investigated by scanning electron microscopy and electron backscatter diffraction. The results show that, the diversity of triple junction types was increased by GBE significantly. The size and morphology of grain boundary carbide were not only affected by the grain boundary character, but also the nearby grain boundary character at the triple junction. The higher sigma values of the nearby grain boundaries, the larger carbide precipitated on the other grain boundary. Based on the experimental results, the effects of grain boundary characters and triple junction types on the carbide precipitation behaviours are discussed.