Transmission electron microscopy for microstructural characterization of the laser clad Ni-Cr-B-Si-C alloy

The microstructure of laser cladding Ni-Cr-B-Si-C alloy is composed of blocky CrB type chromium carbon borides Cr₇C₃ type chromium boron carbides, cellular-dendritic γ-Ni solid solution and various eutectic products. Either an eutectic of γ-Ni+M₂₃C₆ or an eutectic of γ-Ni+nickel borides forms depending on the local composition. γ-Ni/Ni₃B stable solidification and γ-Ni/Ni₂B metastable solidification take place at the same time because of the rapid solidification. The high stress induced by rapid solidification leads to the high density twin in Cr₇₃ and M₂₃C₆ carbides. In the clad, an amorphous phase exists, the γ-Ni surrounded by the amorphous phase forms a modulated structure.