- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Recent progress in laser materials processing and synthesis
摘要： Already today, high-power lasers have become indispensable for many areas of material processing such as welding, cutting, engraving or drilling. Without them, many industrial production processes are no longer possible. In the age of Industry 4.0, the integration of intelligent production systems and advanced information technologies, laser-assisted material processing, and synthesis will become even more important. Thanks to their high throughput, great precision, and efficiency as well as the excellent quality of the processed products laser-based technologies are on the way of becoming one of the most important processing and production routes of the future. By changing laser parameters such as wavelength or pulse durations many different types of materials, including metals, polymers, ceramics, and their composites can be processed. The energy required for processing can be provided in a localized volume with negligible heat transfer to the surrounding components. Due to these unique properties of lasers, new applications of the laser as a material processing tool are continuously made available. New process pathways in additive manufacturing, surface structuring, material deposition or nanoparticle synthesis are among the newer application areas of lasers.
关键词： nanoparticle synthesis,laser materials processing,laser synthesis,additive manufacturing,high-power lasers
更新于2025-09-23 15:19:57
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Multi-scale process simulation for additive manufacturing through particle filled vat photopolymerization
摘要： The majority of research into vat photopolymerization (VP), has been focused on experimental investigations of the influence of process and material parameters. In a specific application of the VP technique, where the resin is filled with particles, this empirical approach has its limitations. In order to fully understand the relation between process parameters and the material properties a detailed numerical analysis is needed. In this paper we present a multi-scale and multi-physical simulation approach to unravel such relations in the complex production process. Using a homogenization approach, the influence of the filler particles, in this case alumina, on the light scattering, conversion characteristics and resulting effective thermal and mechanical properties is determined. The effective composite material and scattering properties are then used as input in a process simulation framework. This enables prediction of key filled-VP characteristics at a structural level. A mesh sensitivity analysis at the component scale reveals that adequate predictions may be obtained with a rather course discretization, facilitating multi-physics VP part simulations.
关键词： Homogenization framework,Multi-physical modeling,Process simulation,Ceramics,Additive manufacturing,Vat photopolymerization,Multi-scale modeling
更新于2025-09-23 15:19:57
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A review of metal additive manufacturing technologies: Mechanism of defects formation and simulation of melting and solidification phenomena in laser powder bed fusion process
摘要： In this review, the analysis of melting and solidification phenomena and the mechanism of the occurrence of defects as well as the analysis of melting and solidification using the numerical simulation in laser powder bed fusion (LPBF) process were introduced. In addition, the strategies of suppression of defects were described. The melting and solidification phenomena during LPBF process are relatively similar to those during welding. Since the plume brings about the strong recoil pressure on the melt pool, the keyhole takes place. And when the depth of keyhole becomes more than a threshold, the keyhole pore remains at the bottom of melt pool. Since the plume also brings about spattering and blows out powder, the gas pores are prone to occur easily. The micro-simulation of melting and solidification enables to reproduce the real phenomena. The macro-simulation of melting and solidification phenomena is one of the effective tools to predict the optimum fabrication condition. In order to prevent the occurrence of defects, it is significant not only to obtain the optimum fabrication condition using the process map but also to develop the simulation software. In addition, the use of the monitoring and feedback control system is greatly effective. Therefore the development of the cyber-physical system is needed.
关键词： Numerical simulation,Process parameters,Additive manufacturing,Melting phenomena,Powder bed fusion,Defect,Laser
更新于2025-09-23 15:19:57
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Microstructure and properties of Tia??Zr congruent alloy fabricated by laser additive manufacturing
摘要： In the present work, Ti40Zr (atomic percent) congruent alloy, as well as four other Ti-Zr alloys near the congruent point, was fabricated using laser additive manufacturing (LAM) on pure titanium substrate. Comparative analyses of these alloys were performed based on microstructure, mechanical properties, tribological properties, corrosion resistance, and formability. The results show that the microstructure of the alloys develops sequentially from the Widmanst?tten structure to nearly full b -(TiZr) columnar crystals for 40 at.% Zr, to b -(TiZr) columnar crystals plus granular a -(TiZr) with the increase of Zr addition. The Ti60Zr40 congruent alloy with nearly full b -(TiZr) structure presents a novel combination of ductility, corrosion resistance, and formability, but it has a slightly lower hardness, less strength and poor tribological properties, compared with the other Ti-Zr alloys near the congruent point. Therefore, to develop the congruent alloy as a high strength LAM material through alloying is very significant.
关键词： Congruent Alloy,Laser additive manufacturing,Titanium alloy,Properties,Microstructure
更新于2025-09-23 15:19:57
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The effect of manufacturing defects on the fatigue life of selective laser melted Ti-6Al-4V structures
摘要： The manufacturing defects introduced by selective laser melting typically lead to lower fatigue strength and a larger variation in fatigue life compared to conventionally manufactured structures. X-ray micro computed tomography (μCT) is used to characterize the porosity and lack of fusion defects in terms of population, morphology, dimension and location. The defect size and location are combined with the NASA/FLACGRO (NASGRO) fatigue crack growth model to predict the likely fatigue life, in which an effective initial crack length is defined using the cyclic plastic zone and the defect radius. An eXtended defect zone (XDZ) describing the propensity for local plasticity during fatigue around a defect has been shown through numerical analysis to be a good indicator of the ranking of the threat to fatigue caused by differently located manufacturing defects. This indicates that the effect of a defect, initial radius, r0, is likely to be pronounced when its center is within 2r0 of the surface and maximal when it lies just beneath the surface.
关键词： Additive manufacturing,High cycle fatigue (HCF),Fatigue crack initiation and growth,Digital printing,Defect tolerance method
更新于2025-09-23 15:19:57
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An investigation on the measurement of instantaneous temperatures in laser assisted additive manufacturing by thermal imagers
摘要： Powder bed fusion additive manufacturing processes has started to be investigated by means of temperature distribution and change on parts, since problems such as residual stresses, deformations, microstructural differences and lack of mechanical properties were observed due to temperatures of parts during manufacturing. In the current studies, thermal cameras were used to analyze thermal history of parts. Depending on the accuracy of thermal cameras, temperature values were varied. In this study, a mathematical model which was supported by the data of experimental tests was developed to obtain increased accuracy. Melt pool temperatures were predicted by using the model which consisted of average temperature and extrapolated measurement area approaches. Melt pool temperatures were calculated ranging between 1700 and 2800 °C. Besides, temperature-dependent cooling rate was considered in the model to improve accuracy of temperature measurement. In addition, finite element analysis of manufacturing process was performed to verify results. Comparison between results of the mathematical equations and finite element analysis showed the accuracy as minimum 85% and maximum 98%. A trusted equation was generated to calculate melt pool temperatures by using an ordinary thermal imager.
关键词： Thermal imager,Additive manufacturing,Powder bed fusion,In-situ monitoring
更新于2025-09-23 15:19:57
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In-process measurement of melt pool cross-sectional geometry and grain orientation in a laser directed energy deposition additive manufacturing process
摘要： Understanding the behaviour of melt pool during laser directed energy deposition (L-DED) is essential for the prediction and control of process quality. Previous effort was focused on the observation of melt pool surface characteristics. In this paper, a coaxial imaging system was employed to determine the melt pool cross sectional geometry and to predict solidified grain orientation during a high deposition rate L-DED process. The image processing procedure, deposition track cross-sectional profile prediction and the relationship between melt pool shape and melt pool dynamics, and grain growth orientation were investigated. Results show that sharp melt pool edges can be obtained so that melt pool width can be predicted with an accuracy of more than 95%. The estimation method of melt pool length has an accuracy of 90%. With the experimental melt pool width and depth data, the cross-sectional profiles of deposited track are predicted at an accuracy of 92% and a good match with experimental data is obtained. The melt pool formation is found to be able to allow the prediction of crystal growth directions during solidification.
关键词： Melt pool dimension,Laser additive manufacturing,Track geometry,Laser directed energy deposition,Grain growth
更新于2025-09-23 15:19:57
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[The Minerals, Metals & Materials Series] TMS 2020 149th Annual Meeting & Exhibition Supplemental Proceedings || Critical Quenching Rates After Solution Annealing: Peculiarities of Aluminuma??Silicon Alloys Fabricated by Laser Powder-Bed Fusion
摘要： Hot isostatic pressing is commonly used to reduce the porosity of (sand-)cast age-hardenable Al-alloys in order to meet the high quality requirements defined by aircraft and automotive industries. In order to establish additive manufacturing methods, such as laser powder-bed fusion (L-PBF), hot isostatic pressing can be utilized to reduce the anisotropic mechanical properties in as-built condition and at the same time eliminate porosity. For the cast aluminum alloy A356, a gas pressure of 75 MPa during hot isostatic pressing lowers the critical cooling rate required to achieve an oversaturated solid solution to about 1 K/s, which is significantly lower than the required quenching rate at atmospheric pressure (2–4 K/s). Thus, an oversaturated state of dissolved magnesium and silicon atoms within the aluminum matrix of cast alloys can easily be achieved in modern hot isostatic presses, thereby avoiding the necessity of a separate solution annealing step. In this work, we applied hot isostatic pressing followed by rapid quenching and direct aging to age-hardenable aluminum alloys processed by both sand casting and laser powder-bed fusion. It was shown that the proposed process of direct aging could be utilized for post-heat treatment of additively manufactured age-hardenable aluminum alloys to open up new fields of applications, for which components have to possess a high fatigue resistance.
关键词： Hot isostatic pressing,Critical cooling rate,Additive manufacturing,Fatigue resistance,Laser powder-bed fusion,Selective laser melting
更新于2025-09-23 15:19:57
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Enhancing Hardness and Wear Performance of Laser Additive Manufactured Ti6Al4V Alloy Through Achieving Ultrafine Microstructure
摘要： Refining microstructure is an important issue for laser additive manufacturing (LAM) of titanium alloy. In the present work, the microstructures of LAM-fabricated Ti6Al4V alloy were refined using a low energy density with the combination of a small spot diameter, a low laser power, and a high scanning speed. The microstructure, hardness, wear performance, and molten pool thermal behavior of LAM-fabricated Ti6Al4V coatings were studied. The results show that the grain sizes of both prior β and α phases are strongly dependent on the cooling rate of the molten pool. The fine prior β grains and submicron-scale acicular α phases were obtained under a low energy density of 75 J mm?2 due to the high cooling rate of the molten pool. In addition, the as-fabricated Ti6Al4V sample with submicron-scale acicular α phase showed a very high hardness of 7.43 GPa, a high elastic modulus of 133.6 GPa, and a low coefficient of friction of 0.48. This work provides a good method for improving the microstructure and mechanical performance of LAM-fabricated Ti6Al4V alloy.
关键词： wear properties,hardness,laser additive manufacturing,titanium alloy,microstructure
更新于2025-09-23 15:19:57
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Femtosecond Laser Additive Manufacturing of Multi-Material Layered Structures
摘要： Laser additive manufacturing (LAM) of a multi-material multi-layer structure was investigated using femtosecond fiber lasers. A thin layer of yttria-stabilized zirconia (YSZ) and a Ni–YSZ layer were additively manufactured to form the electrolyte and anode support of a solid oxide fuel cell (SOFC). A lanthanum strontium manganite (LSM) layer was then added to form a basic three layer cell. This single step process eliminates the need for binders and post treatment. Parameters including laser power, scan speed, scan pattern, and hatching space were systematically evaluated to obtain optimal density and porosity. This is the first report to build a complete and functional fuel cell by using the LAM approach.
关键词： femtosecond laser,laser,fuel cell,additive manufacturing,fiber laser,YSZ,SOFC
更新于2025-09-23 15:19:57