材料期刊网

An 8 mm-high NiCoCrAlYTa coating was epitaxially built-up on a directionally solidified (DS) Ni-based superalloy blade tip by electro-spark deposition. Epitaxial morphologies of the coating and its microstructural characteristics were investigated by means of SEM, XRD and TEM etc. It is observed that the fine column-like dendrites originated from the gamma'-particles or gamma'-clusters of the DS substrate and are un-continuously coarsened. The beta-phase particles precipitate and grow eutectically with the gamma-phase. The orientation of fine column dendrites depends on electro-spark deposition processing parameters and the microstructure can be characterized with superfine gamma and beta phases.