Microstructure And Performance Study On Laser Cladding And Induction Self-propagating Sintering Synthesis Of Ni-Nb-Sn System

Ni-Nb-Sn amorphous composite coating are successfully produced by the laser cladding on45steel substrate. The microstructure, structure, properties of laser cladding layers and theinfluence of different process parameters on it are studied. The results show that the coatinglayer and the matrix have a good metallurgical combination, the cladding layer is uniform, ithave no macro defects of holes, bubbles, inclusion or crack. From the outside to the inside ofcoating is respectively is the cladding area （CZ）, combined area （BZ）, heat affected zone （HAZ）and the matrix. the surface layer is composed of tiny morphology branches crystal and cellularcrystal; the central is branches crystal and plane crystal; heat affected zone is martensite andaustenite; the matrix is ferrite, pearlite and some not melt carbide. XRD analysis shows that themain phases of coating are organized by amorphous phase, Ni₃Nb, Ni₃Sn₄, Nb₂O₃, SnO and Ni.Microhardness, wear-resisting performance and corrosion resistant performance is tested forcoating at the same time, the results show that the hardness, wear resistance and corrosionresistance has greatly improved after laser cladding. When the laser power of Ni-Nb-Snamorphous composite coating reached3.3kW, the highest hardness of cladding layer is thesurface coating, which is1451.8HK; The minium of wear rate is0.195g/cm²; the minium weightgain per unit area is0.026g/cm²in the salt spray test, the performance is the best.In order to obtain better amorphous coating, the Ni42Zr30Ta28composition are designed byusing the e/a-constant line and e/a-variant line criterion. The results show that the laser power ofNi-Zr-Ta amorphous composite coating is3.3kW, the highest hardness of cladding layer is thesurface coating, which is2954.8HK; The minium of wear rate is0.462g/cm²; the minium weightgain per unit area is0.01774g/cm²in the salt spray test, the performance is the best.Ni-Nb-Sn powder have a very strong laser sintering self-propagating phenomenon in lasercladding process, so a new technique which is using laser induced self-propagating reactionsynthesis to fabricate amorphous alloys is made. The microstructure, structure, properties of lasercladding layers and the influence of different process parameters on it are studied. The resultsshow that the main metal alloys organization are some nanocrystalline phase, Ni₃Sn₄, Ni₃Nb, Niand NbO2; when the pressure is50kN and the laser power is500W, the highest microhardness is807.9HK, and the Wear rate is0.1365g/cm², the performance is the best.