Study On Microstructure Of Ni-based Alloy

The frame spraying-induction re-cladding technology on the surface of 45 steel with Ni-based self-fluxing alloy is studied. By the studies of microhardness, microstructure and mechanical property, it is practical to study the relations between hard phases and microstructure or mechanics performance.X-ray diffractometer(XRD) was needed in this experiment. The results indicated that the coating substrate was Ni-based solid solution. The hard phases in WC/Ni coating are WC,Cr3C2 basically which enchase in the coating hardly. The hard phases in TiC/Ni coating are TiC,Cr3C2 basically which enchase hardly in the coating surface. And inner substrate. As for the Ni-based alloy coating, the hard phase are composed of boride(CrB) dispersed on the Ni-based coating surface.The microstructure of coatings and interfaces was analyzed by means of Metallurgical Microscope (MM) and scanning electronic microscope(SEM). The results indicated that the coating was compact, the powder particles distorted greatly. Many hard phases enchase in the coating substrate or distribute on the coating substrate surface hardly. There are some transition of particles between sublaye and working layers. The combination condition between sublayer and copper base is interlaced, and exists at the copper side near the interface, which indicates that the coating and copper base come to a good combination.The microhardness distribution of coatings and interface were studied using micro-hardness instrument. The results indicated that the microhardness of WC/Ni coatings was different remarkably with the difference of WC content in WC/Ni powders in coating landscape orientation, microhardness of 5%WC/Ni coating was the lowest(about HV504.96 averagely), the highest microhardness was belong to the 15%WC/Ni coating(about HV592.82), microhardness of 5%TiC/Ni coating was the lowest(about HV430.82 averagely), the highest microhardness was belong to the 15%TiC/Ni coating(about HV464.14). As for the Ni-based coating, the microhardness distribution is quite symmetrical, the average microhardness is about HV333.62. In the lengthways coating section, the microhardness increases gradually from coating surface to interior, which indicates that surface coating is loose, interior coating is compact correspondingly.Ni-based alloy affiliated with hard phases WC and TiC is tested in microstructure and mechanical property to find the disciplinarian between hard phases and microstructure or property. The experiment result indicated that Ni-based alloy can fulfill the demand of induction re-cladding, and affiliating with hard phases WC and TiC can enhance greatly the mechanical property of coating.