The overlay of boride cermet had been fabricated on low carbon steel by plasma transfered arc welding with the composite powders made from MoB, Ni and etc.. The micro-structure consisted of dispersed Mo2NiB2 particles and Ni matrix had been formed successfully by using the semi-sintered powder. However, this boride cermet is not so suitable to overlay alloy, because it is too difficult to control its microstructure of overlay to various sized steel parts.
Improvement in stability of microstructure was achieved by alteration of the compositions. The composite powders made from CrB, Fe and etc. was welded to carbon steel, and the cermet layers of Mo2(Fe, Cr)B2 ceramics and Fe-Cr alloy were obtained as a result. The microstructure is not so sensitive to welding conditions, due to relative slow growth of Mo2(Fe, Cr)B2 ceramics.