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DEFORMATION ANALYSIS OF H62 Cu ALLOY FOIL SUBJECTED TO MULTI-PULSED LASER DYNAMIC FORMING: SIMULATIONS
摘要： By utilizing the ABAQUS software, this paper simulates and analyzes the forming of the H62 foil subjected to multi-pulse laser dynamic forming (LDF). The Johnson–Cook failure mode is adopted to predict the fracture threshold value of the H62 foil. Compared with the single-pulsed LDF, the multi-pulsed LDF improves the limit depth and forming quality of the foil e?ectively. With the increase of impact number, the uniformity of foil is e?ectively improved. Appropriate peak pressure and impact number are important to increase limit forming depth and improve forming quality.
关键词： finite element analysis,Laser dynamic forming,H62 Cu alloy foil,limit forming depth,multi impacts
更新于2025-09-19 17:13:59
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Technological Feasibility of Lattice Materials by Laser-Based Powder Bed Fusion of A357.0
摘要： Lattice materials represent one of the utmost applications of additive manufacturing. The promising synergy between additive processes and topology optimization finds full development in achieving components that comprise bulky and hollow areas, as well as intermediate zones. Yet, the potential to design innovative shapes can be hindered by technological limits. The article tackles the manufacturability by laser-based powder bed fusion (L-PBF) of aluminum-based lattice materials by varying the beam diameter and thus the relative density. The printing accuracy is evaluated against the distinctive building phenomena in L-PBF of metals. The main finding consists in identification of a feasibility window that can be used for development of lightweight industrial components. A relative density of 20% compared with fully solid material (aluminum alloy A357.0) is found as the lowest boundary for a 3-mm cell dimension for a body-centered cubic structure with struts along the cube edges (BCCXYZ) and built with the vertical edges parallel to the growth direction to account for the worst-case scenario. Lighter structures of this kind, even if theoretically compliant with technical specifications of the machine, result in unstable frameworks.
关键词： additive manufacturing,lattice,aluminum alloy,laser-based powder bed fusion
更新于2025-09-19 17:13:59
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Study on laser cladding and properties of AZ63-Er alloy for automobile engine
摘要： Aiming at the problem of the poor corrosion resistance of magnesium alloys for automobiles, Al-TiC and Al-TiC-Y2O3 cladding layers were prepared on the AZ63-Er alloy by laser cladding technology, studied the effects of Al:TiC mass ratio and Y2O3 addition on the microstructure, phase composition, hardness and corrosion resistance of the cladding layer. The results show that the Al-TiC laser cladding layer with different mass ratios has metallurgical bonding with AZ63-Er alloy substrate, and there are no pores or cracks at the interface. The main phases of the Al-TiC laser cladding layer are Ti3AlC, TiC, Mg2Al3, Al3Mg2, Al, Mg, AlMg and Ti6O. The hardness of laser cladding layer with the mass ratios of Al:TiC are 8:1, 4:1 and 2:1 are about 2.75, 3.24 and 3.94 times of the substrate. The corrosion resistance of Al-TiC cladding layer is higher than that of the AZ63-Er alloy substrate, and the corrosion resistance of the Al:TiC cladding layer with the mass ratio of 8:1 is the best. Al3Y and Al4MgY phases are formed in the Al-TiC-Y2O3 cladding layer after Y2O3 addition. The hardness of the Al-TiC-Y2O3 cladding layer is significantly higher than that of the Al-TiC cladding layer. The Al-TiC-Y2O3 composite cladding layer has the best hardness and corrosion resistance when the Y2O3 content is 0.6%.
关键词： surface modification,laser cladding,hardness,AZ63-Er alloy,corrosion resistance
更新于2025-09-19 17:13:59
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Efficiency Enhancement of Dye-Sensitized Solar Cells Using Tia??Nb Alloy Photoanodes with Mesoporous Oxide Surface
摘要： A native mesoporous titanium-niobium oxides layer on a Ti-6wt%Nb alloy sheet surface prepared through H2O2 pretreatment was successfully developed as an ef?cient photoanode for a dye-sensitized cell (DCCS). This alloyed mesoporous structure not only provided an increased surface area in contact with screen-printed TiO2 nanoparticles but also enabled Nb alloying in sintered nanoparticle deposits. Improvement of energy conversion ef?ciency of DSSCs can be increased up to 22% using H2O2 pretreatments with a proper post-annealing, and the mesoporous Ti–Nb photoanodes enhanced conversion ef?ciency by 15.2% to 18.3%, compared with unalloyed structures. EIS results under dark current indicate that DSSCs with mesoporous Ti–Nb photoanode exhibited a greater inhibition of recombination of electrons and holes at the interfaces of Nb-doped TiO2/dye/electrolyte layer due to energy barriers.
关键词： Efficiency enhancement,Mesoporous oxide surface,Ti–Nb alloy,Photoanodes,Dye-sensitized solar cells
更新于2025-09-19 17:13:59
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Ultrasensitive Field‐Effect Biosensors Enabled by the Unique Electronic Properties of Graphene
摘要： Using Li metal-free anodes for lithium-ion oxygen and lithium-ion sulfur batteries is considered as a promising solution to resolve the hazard of Li metal anode. Although Si anode exhibits high capacity and low electrochemical potential, it cannot match with oxygen (or sulfur) cathode, because both lack cycleable lithium ions. In this work, a free-standing and fibrous Si/C anode is prepared by electrospinning and its simple but effective lithiation is proposed. When assembling the cells, the free-standing Si/C anode was put between mass-controlled lithium metal foil and separator, and then the Si/C anode could be lithiated after adding electrolytes. By optimizing a LiFSI based ether electrolyte, the Si/C anode could achieve good cycleablity comparable to that in carbonate electrolytes. The lithiated SieO2 cells exhibit better cycling stability than the lithium oxygen cells with gel polymer electrolye. Moreover, because both Si anode and S@pPAN cathode are compatible with carbonate electrolytes, exceptional cycling performance has been achieved for the lithiated SieS cells. This simple method could pave the way to commercial applications of lithium-ion oxygen and lithium-ion sulfur batteries.
关键词： Lithium-sulfur battery,Lithium-oxygen battery,LieSi alloy anode,In-situ lithiation,Fibrous Si/C anode
更新于2025-09-19 17:13:59
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Modeling of Keyhole-Induced Pore Formation in Laser-Arc Hybrid Welding of Aluminum Alloy with a Horizontal Fillet Joint
摘要： A three-dimensional transient model is proposed to investigate the weld pool dynamic behavior in laser + metal inert gas (MIG) hybrid fillet welding of aluminum alloy in the horizontal position, which allows for the joint configuration and coupling of the keyhole, droplet and weld pool as well as the heat and mass exchange between gas and liquid phases and is able to simulate the temperature distribution, fluid flow and formation process of a keyhole-induced pore in hybrid welding with a horizontal fillet joint. The weld porosity is also measured using x-ray nondestructive testing technology. Keyhole behavior and the formation mechanism of keyhole-induced porosity were analyzed. The calculated results are in generally good agreement with the experimental ones. A clockwise vortex always exists at the middle part of the weld pool. The formation and growth of the molten metal bulge on the keyhole wall are responsible for the occurrence of a gas bubble, which has a variation in size and shape and can be split during welding. The keyhole collapses easily at its middle or upper part in horizontal fillet welding, and the capture of the bubble by the upper molten pool boundary enhances the possibility of porosity formation to some degree. The keyhole-induced pore is mainly formed at the regions near the keyhole bottom and the upper fusion line of the weld pool.
关键词： horizontal fillet joint,numerical analysis,aluminum alloy,hybrid welding,pore formation
更新于2025-09-19 17:13:59
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Predicting the fatigue life of an AlSi10Mg alloy manufactured via selective laser melting by using data from Computed Tomography
摘要： A modelling strategy is proposed to evaluate the influence of defect morphology on the fatigue limit of additively manufactured Al alloys by: (i) obtaining an x-ray micro-computed tomography (μ-CT) 3D image of the material, (ii) computing the Equivalent Inertia Ellipse of each individual pore, (iii) modelling the influence of the defect on the fatigue limit through the DSG approach and, (iv) 3D mapping the criticality of each individual defect. For this fatigue study, an AlSi10Mg alloy was manufactured by selective laser melting using sub-optimal deposition parameters in order to produce large lack-of-fusion defects. After a T6 heat treatment, tension-compression fatigue tests, with R = -1, were conducted on specimens oriented with their loading axis either parallel or normal to the Z-axis of the additive manufacturing equipment. Two samples were characterised before μ-CT testing in order to characterise the initial 3D defect population. Each sample was fatigued step by step in order to determine the fatigue limit. The fracture surface was then carefully observed using a scanning electron microscope (SEM) in order to identify the critical defect in the initial μ-CT image. A comparison with the fatigue results led to the following conclusions: (i) when the longest axis of the defect is perpendicular to the load axis, modelling the defect as an equivalent inertia prolate ellipse gives better results (5 % error on the fatigue limit) than modelling it as a simple equivalent sphere (22 % error on the fatigue limit), (ii) the prolate ellipse is not relevant when the longest axis of the defect is oriented along the loading axis; in this case an oblate equivalent ellipse should be used, (iii) the concept of ‘size’ for a complex 3D shaped defect should be linked to the inertia and the loading, (iv) with this approach, surface defects are shown to be more critical than internal ones for fatigue life and, (v) a 3D defect criticality map of the entire sample can be plotted to provide visual feedback on which defects are the most critical for fatigue life.
关键词： AlSi10Mg alloy,defect morphology,selective laser melting,fatigue life,Computed Tomography
更新于2025-09-19 17:13:59
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Underwater wire-feed laser deposition of the Ti–6Al–4V titanium alloy
摘要： Underwater wire-feed laser deposition (UWLD) of the Ti-6Al-4V alloy was firstly carried out utilizing a laser deposition nozzle, and the deposition appearance, geometry characteristics, microstructure and microhardness of deposited tracks were studied. At a lower gas flow rate, the absorption of residual water and scattering of aerosol particles on laser beam caused UWLD instability and decreased molten metal wettability. Upon increasing the gas flow rate, the aerosol particle density decreased, increasing the laser density and decreasing the cooling rate of molten metal; thus, the height and deposition angle of UWLD track decreased as the corresponding width and fusion depth increased. The microstructures of the deposited metal at a gas flow rate of 10 L/min were composed of the coarse lath α phase in upper region and the acicular martensite α′ with different size scales in middle and bottom regions. With increasing the gas flow rate to 20 L/min, the microstructure was primarily acicular martensite along with a small amount of α phase, and the martensite exhibited a larger grain size and stronger texture. At a gas flow rate of 20 L/min, the deposited process was stable and uniform deposition track without oxidation layer was obtained for UWLD Ti-6Al-4V alloy.
关键词： Ti-6Al-4V alloy,Laser propagation mechanism,Microstructure,Microhardness,Underwater wire-based laser deposition,Geometrical characteristics
更新于2025-09-19 17:13:59
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Influence of Laser Power on Grain Size and Tensile Strength of 5A90 Al–Li Alloy T-joint Fabricated by Dual Laser-Beam Bilateral Synchronous Welding
摘要： Dual laser-beam bilateral synchronous welding is introduced to produce the 2.5 mm thick 5A90 Al–Li alloy T-joint. The grain morphology and grain size of weld metal (WM) in the T-joint are analyzed and calculated. The tensile experiment, scanning electron microscopy and energy disperse spectroscopy are respectively employed to study the tensile strength, fracture morphology and chemical composition of the T-joint. The results reveal that when the laser power is increased from 2500 to 3000 W, the grain sizes of fine-grained layers and columnar dendrites near the fusion line are significantly reduced. Conversely, that of equiaxed dendrites at the WM center is not sensitive to the variety of laser power. Moreover, the degree of elemental segregation in WM near the fusion line is also aggravated with the increasing of the laser power. The tensile strength of the T-joint with the laser power of 2500 W is significantly higher than that with the laser power of 3000 W. The tensile fracture locations are occurred in the weld toe with obvious pores, shear dimples and tear ridges, which are the typical characteristics of ductile fracture. Besides, the chemical compositions of the second phase particles in the WM are more sensitive to than the variation of laser power compared with that of the matrix.
关键词： T-joint,5A90 Al–Li alloy,Tensile strength,DLBSW,Gain size
更新于2025-09-16 10:30:52
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Rapid synthesis of metallic and alloy micro/nanoparticles by laser ablation towards water
摘要： A versatile method named laser ablation towards water (LATW) was developed to rapidly and simply synthesize metallic and alloy micro/nano particles, even high-entropy-alloy nanoparticles (NPs). A nanosecond pulsed laser beam passed through a transparent glass substrate, ablated its coated metallic ?lm in the air or contacting with water, and synthesized a colloidal solution contained the micro/nano particles. In this study, Cu microparticles (MPs, Daverage = 1.8 μm), Cu MPs with Cu2O NPs, Cu2O NPs and Au NPs (Daverage = 9.5 nm) were successfully synthesized by the laser ablation of 10 μm Cu ?lm in the air, 10 μm Cu ?lm in the water, 200 nm Cu ?lm in the water, 200 nm Au ?lm in the water, respectively. The content of bimetallic NPs can be adjusted by the relative thickness ratio of bilayer ?lm using laser ablation. Moreover, the ternary (Au-Ag-Cu), quaternary (Au-Ag-Cu-Pt), and quinary (Au-Ag-Cu-Pt-Ni) alloy NPs were also fabricated by the laser ablation of multilayer metallic ?lm in the water. Therefore, LATW is a ?exible technique for the high-e?ective synthesis of MPs, NPs, and various alloy NPs.
关键词： Laser ablation,Microparticles,Alloy nanoparticles,Nanoparticles,Water
更新于2025-09-16 10:30:52