Effect of Cu and Mo on the microstructure and properties of Ni-based alloy spray welding coatings

Two spray coatings were prepared by thermal spray weld with two kinds of Ni-based alloy powders, named as Ni-A and Ni-B. XRD and SEM results show that the substrates of Ni-A and Ni-B spray coatings are both Ni and FeNi₃, while there is few Cu in Ni-A substrate. Both in Ni-A and Ni-B coatings there are lots of secondary phases with a great proportion of Cr. Secondary phases in Ni-A have two appearances and there is about 20% Mo in them, but secondary phases in Ni-B contain no Mo. The results of high-temperature hardness test make it clear that the hardnesses of Ni-A and Ni-B are high and descend with increasing temperature. The hardness of Ni-A is higher than.the relevant hardness of Ni-B because there is about 20% Mo in the secondary phases of Ni-A.