Fe-Cr-Ni-Mo-Ru alloys produced by laser surface alloying

Laser surface alloying of duplex 2205 stainless steel with preplaced ruthenium powder has been investigated. The microstructure and corrosion behariour of the laser surface alloyed layers were examined by scanning electron microscopy, energy dispersive X-ray spectrometry, microhardness, and open circuit corrosion potential measurements. The microstructure of the surface alloyed layers consisted mainly of fine cellular dendrites: spectrometric analyses indicated that ruthenium contents as high as 23-30 wt-% could he produced. These features are presumed to be responsible for the higher hardness values observed in the alloyed layer. The open circuit corrosion potentials of the layers containing ruthenium were displaced towards more noble values in reducing acid solutions, resulting in spontaneous passivation of the alloy layer surface. © 1996 The Institute of Materials.