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Effects of TiC on the microstructure and properties of TiC/TiAl composite coating prepared by laser cladding
摘要： In order to study the effect of TiC on the microstructure and properties of cladding coatings, TiC/TiAl composite coatings have been prepared by using a laser cladding technique on TiAl alloy, and the microstructure and properties of the resulting composite coatings have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-hardness testing, X-ray stress measurements, friction and wear testing, and an electrochemical workstation. The results showed that when the particle size of TiC is up to micron, the growth of TiC is more developed, the dendrite growth direction is disordered, and the cladding quality is poor. When the particle size of TiC is nanoscale, the morphology of the reinforcement phase TiC is mainly granular and thin rods, which is uniform in the coating and the direction of growth is regular. When the concentration of TiC reaches 20%, the microstructure of the cladding layer grows well and is dense. The microhardness and wear resistance of the coatings prepared by adding nano TiC are better than those of the coatings prepared by micron TiC. When the content of nano TiC in the coatings increases from 10% to 20%, the microhardness and wear resistance of the coatings are obviously improved. The residual stress of the coating is positively related to the crack rate. The residual stress in the coating is tensile stress, and the crack type is the crystal crack in the hot crack. When the particle size of TiC is small and the concentration is high, the coating shows better corrosion resistance.
关键词： TiAl alloy,TiC/TiAl composite coating,Laser cladding,Properties,Microstructure
更新于2025-09-23 15:21:21
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Cracking behavior and control of β-solidifying Ti-40Al-9V-0.5Y alloy produced by selective laser melting
摘要： A β-solidifying Ti-40Al-9V-0.5Y (at.%) alloy with a high cracking sensitivity has been successfully fabricated by selective laser melting (SLM) in this study. The influence factors for cracking sensitivity, cracking behavior and crack inhibition mechanism were investigated. The results show that the effects of process parameters on cracking sensitivity strongly depend on the cooling rate in molten pool with different heat transfer modes. The conduction mode with higher cooling rates exhibits a higher cracking sensitivity in comparison to the keyhole mode. Microstructure characteristics and phase transformations controlled by cooling rate determine the inherent ductility of β-solidifying γ-TiAl alloys during SLM. On this basis, the formation and inhibition mechanism of solidification and cold cracking are proposed. Finally, the crack-free Ti-40Al-9V-0.5Y sample with fine equiaxed microstructures and favorable mechanical properties (microhardness of 542±19 HV, yield strength of 1871±12 MPa, ultimate strength of 2106±13 MPa and ultimate compressive strain of 10.89±0.57 %) can be produced by SLM. The strengthening mechanism can be attributed to grain refinement and precipitation strengthening.
关键词： Phase transformation,Selective laser melting,Cracking behavior,Microstructure,β-solidifying γ-TiAl alloy,Cracking control
更新于2025-09-16 10:30:52