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Microstructure and properties of WC reinforced Ni-based composite coatings with Y <sub/>2</sub> O <sub/>3</sub> addition on titanium alloy by laser cladding
摘要： In this study, WC reinforced Ni-based composite coatings with Y2O3 addition were deposited on Ti-6Al-4V titanium substrate by laser cladding. The phases, microstructure, microhardness and wear resistance of the composite coatings were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, microhardness tester and wear tester. The results showed that good metallurgical bonding was achieved between the composite coatings and substrate. The phases mainly were γ -Ni, TiC, TiB2, Ni3B, M23C6 and WC. Most of the WC was dissolved in small pieces of WC during the laser cladding process. The microhardness of the composite coatings was about 3 times that of the titanium substrate and the wear resistance of the composite coatings had a significant increase.
关键词： titanium alloy,microstructure,Laser cladding,Y2O3,WC,Ni-based composite coatings
更新于2025-11-28 14:24:20
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Laser Alloying of Surface of Ti-5.5Al-2Zr-1Mo-1?V Titanium near-α-Alloy Prepared Via Melted by Pulsed Laser Radiation TiC Particles
摘要： Laser alloying of the surface of Ti-5.5Al-2Zr-1Mo-1 V titanium near-α-alloy was carried out in order to improve the surface properties. The surface of the titanium alloy was being melted by pulsed laser radiation while TiC alloying powder component was being supplied to the laser irradiation zone. As a result of laser alloying, partial melting of the powder particles of titanium carbide and mixing them with the substrate metal resulted in the formation of new disperse TiC phases in the form of dendrites and highly dispersed phases. It is shown that laser alloying of Ti-5.5Al-2Zr-1Mo-1 V titanium near-α-alloy by pulsed laser radiation leads to a 1.4 times increase in hardness of the surface of the titanium alloy and reduces friction coefficient 1.2 times.
关键词： Tribological tests,Laser alloying,Microstructure,Titanium alloy
更新于2025-11-21 11:20:48
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Laser welding characteristics of Ti-Pb dissimilar couples and element diffusion in the molten pool
摘要： Laser welding lead metal to titanium or titanium alloy, which is a typical dissimilar welding process, have a great challenge. Couples of Ti-Pb, Ti6Al4V-Pb were welded by a 3kW continuous wave Nd:YAG laser. The influences of process parameters such as laser power and laser beam offset on welding depth were investigated. Microstructure, element distribution and micro-hardness of the welds were tested. The element diffusion characteristics during laser welding of Ti-Pb couple and Ti6Al4V-Pb couple were studied based on the experiments data. Experimental results show laser beam offset is a primary factor for welding titanium alloy and lead metal, and laser power plays a critical role for welding pure titanium and lead metal. A chemical potential calculation model of Ti-Pb-Al ternary alloy was established. The calculation results show that chemical potential of Ti element increases with enhancing Pb content in Ti-Pb-Al ternary system, however, the chemical potential of Ti element decreases with increasing Pb content in Ti-Pb binary system. According to the calculation results, for Ti-Pb-Al ternary system, because of the Al element in the molten pool, the Ti element tends to diffuse into the Al element, and the diffusion driving force of Ti element to the Pb element is weak. Compared with the Ti-Pb binary system and the Ti-Pb-Al ternary system, it is more likely to form a mixed fusion weld for the binary system, and the mass transfer interface phenomenon is more serious for the ternary system, which is consistent with EDS line scan and microhardness testing results.
关键词： Chemical potential,Interface,Microstructure,Lead metal,Titanium alloy,Laser dissimilar welding
更新于2025-11-21 11:18:25
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Influence of multiple laser peening on vibration fatigue properties of TC6 titanium alloy
摘要： In this study, typical TC6 titanium alloy was taken to investigate the effects of multiple laser peening (LP) on the vibration fatigue properties and microstructural evolution. The vibration fatigue experiments were conducted, while the vibration fatigue life of the specimens before and after LP was compared and the fracture morphologies were observed by scanning electron microscopy (SEM). In addition, the measurements of residual stress and microhardness were carried out. The microstructures produced by different treatments were also characterized by transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD). The experimental results indicated that multiple LP could indeed enhance the vibration fatigue properties of TC6 titanium alloy. Comparing with the investigated specimen without LP, the vibration fatigue life of the specimen subjected to 5 times LP increased by 105.2%. Meanwhile, after 5 times LP, the surface residual stress transformed from tensile stress (+26 MPa) to compressive stress (?485 MPa), and the surface microhardness was 428 HV, which increased by 32.9% compared with the untreated sample. Additionally, high-density of dislocation and deformation twin were also generated after multiple LP. The improvement of vibration fatigue properties was attributed to the rewarding compressive residual stress and the beneficial microstructural evolution induced by multiple LP.
关键词： TC6 titanium alloy,Laser peening,Vibration fatigue properties,Microstructure evolution,Residual stress
更新于2025-11-14 17:04:02
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Plastic anisotropy of laser melting deposited Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy
摘要： Tensile tests of laser melting deposited Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy specimens in different orientations were conducted, which indicates significant plastic anisotropy of this material. Digital image correlation method added in-situ-tensile tests were carried out to investigate mechanical properties with respect to specified material structures. The results indicate that the plasticity properties of the thick columnar grain and that of other grains are significant different. Under the same stress level, the thick columnar grain yield firstly and bear the main plastic deformation of the whole specimen. The elasto-plastic Poisson's ratio of the thick columnar grains and that of other grains are also different. Tests on layer bands indicate that the coarser microstructures of the layer bands lead a stronger resistance to tensile plastic deformation, but a weaker resistance to shear plastic deformation. In addition, the direction of primary α laths on both sides of the layer bands may be different, and this has an obviously effect on the tensile plastic deformation of the specimen.
关键词： Digital image correlation method,Plastic anisotropy,Laser melting deposited,Titanium alloy,Mechanical properties
更新于2025-10-24 16:40:20
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Microstructure and mechanical properties of Ti/Al dissimilar joints produced by laser-MIG welding–brazing
摘要： We butt-welded AA6061 aluminum alloy to Ti6Al4V titanium alloy, dissimilar light metals, by using laser-MIG hybrid welding–brazing without grooves. The parameters of the laser and arc were optimized to produce sound joints with good formation and mechanical properties. The microstructure of the layer of intermetallic compounds (IMCs) was investigated by scanning electron microscopy and energy dispersive spectroscopy. We also tested the tensile strength of the joints with and without reinforcement. The morphology and thickness of the IMCs varied throughout the joints. A continuous thin layer of TiAl3 appeared on the top surface of the Ti6Al4V, on which some rod-like IMCs grew toward the fusion zone. In the upper region of the butt plane, because more heat accumulated there from the high-power laser coupled with the MIG arc, double-layer IMCs with a thickness of ～ 10.0 μm formed, composed of TiAl (near the Ti alloy) and TiAl3 (near the fusion zone). In the lower region of the butt plane, the double-layer IMCs became continuous and uniform, the serrated morphology disappeared, and the thickness of the IMC layer decreased to 4.0 μm. On the backside of the joint, the thickness of the compound layer (TiAl3) was about 1.0 μm. The average tensile strengths of the reinforced and unreinforced joints were 226 MPa and 210 MPa, respectively, which are up to 88% and 81% of the AA6061 tensile strength, respectively.
关键词： dissimilar joint,titanium alloy,intermetallic compounds.,Laser-MIG hybrid welding–brazing,aluminum alloy
更新于2025-09-23 15:22:29
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Microstructure and Characteristic of Biomedical Titanium Alloy Based on Picosecond Laser Micromachining
摘要： Laser micromachining has become a hotspot in recent years due to its high precision, non-contact and adjustable parameter. In this paper, TC4 titanium alloy implant samples were conducted to obtain specific surface textures through picosecond laser. The laser parameters which directly influenced the microstructure and characteristic of surface textures were optimized within the context of laser power, scanning speed and scanning number via response surface methodology. The microstructure was evaluated using scanning electron microscope (SEM) while the feature size of the surface textures was measured through surface 3D profiler. In addition, endothelial cell culture was conducted to investigate the biofunctionalization of samples with specific surface textures. It demonstrated that well-structured textures played an important role in promoting cell adhesion and proliferation for titanium alloy implants.
关键词： Picosecond laser micromachining,Microstructure,Biofunctionalization,Titanium alloy
更新于2025-09-23 15:22:29
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Investigation of arc dynamics during vacuum arc remelting of a Ti64 alloy using a photodiode based instrumentation
摘要： Understanding the arc dynamics during VAR is important for controlling the final quality of the ingot, as the spatial and temporal distribution of the arc dictates the electric current and energy inputs at the ingot top, which in turn affect the hydrodynamics of the metal in the molten pool and the solidification conditions of the ingot. The arc dynamics during vacuum arc remelting was quantitatively investigated based on the analysis of the light emitted by the arc and reflected by the molten pool using photodiodes placed inside a full-scale furnace. The measurements allowed us to determine the location of the arc luminosity centroid and to follow its displacement as a function of time. They were made during the melt of a Ti64 alloy with an imposed alternated electromagnetic stirring of high intensity. The arc dynamics was found to be most of the time periodic, asymmetrical, and strongly correlated to the evolution of the stirring magnetic field. The arc centroid exhibited three regular displacement patterns throughout the melt. A common characteristic to all three patterns was the relative stability of the centroid during stirring plateaus and its rapid motion during stirring ramps. An evolution towards a much more centered distribution of the centroid was observed with the arc power decrease during the hot-topping phase. Possible implications of the observed arc dynamics on the final quality of the VAR ingot are discussed.
关键词： Electric arc,Photodiodes,Titanium alloy,Vacuum arc remelting,Dynamics
更新于2025-09-23 15:21:21
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Effect of laser shock processing on oxidation resistance of laser additive manufactured Ti6Al4V titanium alloy
摘要： The high-temperature oxidation resistance of laser additive manufactured (LAM) Ti6Al4V before and after laser shock processing (LSP) was investigated. The samples were oxidized at 400?800 °C for 1?50 h in air. The results revealed that the rate of weight gain of the Ti6Al4V fabricated through LAM decreased, and LSP had a positive effect on increasing the oxidation resistance. At an oxidation temperature of 700 °C, an aluminum-rich layer was observed in the cross-section before LSP. After LSP, the aluminum-rich layer changed to three layers. The aluminum-rich layer prevented the diffusion of oxygen, which improved the oxidation resistance of the Ti6Al4V.
关键词： Ti6Al4V titanium alloy,High-temperature oxidation resistance,Laser shock processing,Laser additive manufacturing
更新于2025-09-23 15:21:01
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Comparative Study on Microstructure and Aluminum Distribution Between Laser Beam Welding and Electron Beam Welding of Tia??6Ala??4V Alloy Plates
摘要： Ti–6Al–4V alloy plates with a thickness of 4 mm were joined by electron beam welding (EBW) and laser beam welding (LBW). The comparison of LBW and EBW was performed according to grain morphology, microstructure, aluminum distribution, and microhardness of the joints. Results indicate that compared with LBW joint, more equiaxed grains are observed around the central zone of the EBW joint. The microstructure in fusion zone (FZ) of EBW joint presents more uneven with obviously coarser acicular martensite α′. Moreover, the aluminum element content of EBW joint is substantially lower, which demonstrates a more significant burning loss behavior in EBW process. The lower aluminum content in the upper center areas of the joints is attributed to the more significant element burning loss caused by higher temperature, whereas more uniform aluminum distribution in the upper part of the joints is ascribed to stronger convection form within the upper part of the joint. In addition, the characteristics of convection and thermal field within the molten pool are recognized as vital factors influencing the aluminum distribution. The lower microhardness profile in FZ of the EBW joint is principally attributed to coarser acicular martensite α′ and lower aluminum element in EBW joint.
关键词： Electron beam welding,Microhardness,Microstructure,Burning loss,Titanium alloy,Laser beam welding
更新于2025-09-23 15:21:01