Study On Preparation Of Aluminum Base Amorphous Alloy Coating By Laser Cladding

The aluminum alloy has been widely used in the fields of autotive industry，maritime transport，military and spaceflight because of its high intensity，good formingquality，low density and so on. But its low hardness，poor wearing resistance andcorrosion resistance limit its wide application. Meanwhile，amorphous alloy has highhardness，good wearing resistance and corrosion resistance. Laser cladding has highheating rate and cooling rate. If the amorphous coat could be prepared by laser cladding，the hardness and corrosion resistance of aluminium alloy will be observably improvedand its applied range could be expanded.In this paper，we summarize the theory and process flow of laser cladding，choosecoating composition and determine the relationship between laser process parameter andcoating thickness. We got good quality alloy coating by placing Al-Ni-Y alloy powder inadvance and choosing suitable laser process parameter.The microstructure，element distribution，phase and microhardness have beenanalyzed with the aid of optical microscopy， SEM and EDS， XRD andmicrohardness-tester. The result showdthat the coatings have smooth and continuoussurface and metallurgical bond to the substrate. The microstructures were typicalextension growth on plane basis at the cladding layer bottom,cellular crystals near thebonding zone，dendrite crystal in the middle of the molten layer and equiaxed crystals atthe top of the cladding layer. It have more Ni and Y in the central area of cladding layer.Most of them distribute in the grain boundary with mesh. The dominant phases in thecladding zone are oxide YAlO₃、Y₃Al₅O₁₂、Y₂O₃、NiAl₂₆O₄₀、NiAl₃₂O₄₉etc andcompounds Al₄NiY、Al₂Y₃、Y₅Al₃、Al₃Ni₂、Al₄Ni₃、Ni₃Y、NiY etc. The cladding layer’saverage microhardness enhance from40HV to71.7HV. The composition of claddinglayer still has some difference with the highest glass forming ability. And the result of XRD has no proof of amorphous. They showed that it’s hard to prepare amorphous coatby laser cladding with existing conditions.The main problems and their improving methods of laser cladding Al-Ni-Y alloyscoating on aluminum alloys were elucidated. And finally，the future work was putforward.