Processing parameter, microstructure hardness of Ni base intermetallic alloy coating fabricated by laser cladding

Ni base intermetallic alloy coating was fabricated by laser cladding, controlling the laser power and powder feed rate. Atomized powder of the Ni base intermetallic alloy was laser-cladded on the substrate of stainless steel 304. The hardness and microstructure of the clad layers were investigated by Vickers hardness test; SEM, XRD and TEM observations. The hardness of the cladding layer was affected by the dilution with the substrate; it increased with decreasing laser power and increasing powder teed rate. By optimizing the dilution with the substrate, the cladding layer with an almost identical hardness level to that of the Ni base intermetallic alloy fabricated by ingot metallurgy was obtained. The TEM observations revealed that a very fine sized microstructure composed of Ni3Al and Ni3V was partially formed even in the as-cladded state. After annealing; the two-phase microstructure composed of Ni3Al and Ni3V was developed in the cladding layer, resulting in enhanced hardness in the cladding layers fabricated in the majority of cladding conditions.