Laser surface alloying of NiCrSiB on Al6061 aluminium alloy

NiCrSiB powder was mixed with a binding agent and then painted onto the roughened surface of Al6061 for laser surface alloying using a high-power Nd-YAG laser. With optimum process parameters, NiCrSiB can be successfully alloyed onto the aluminium alloy surface with good metallurgical bonding between the alloyed layer and the substrate. A porosity- and crack-free surface was achieved by overlapping single tracks. The surface consists of a fine dendritic structure of intermetallic compounds of NiAl. A surface hardness of 900 Hv was noted. Uneven distribution of Ni content along the depth of the alloyed surface was observed. The laser-alloyed surface has improved corrosion and protection potentials and the same pitting potential as compared with those of the Al6061. In the vibratory cavitation erosion test in 3.5%NaCl, the weight loss of the specimen with a NiCrSiB alloyed surface was half of that of the Al6061.