Additive manufacturing最新文献

{"title":"Achieving high strength-ductility of AZ91 magnesium alloy via wire-arc directed energy deposition assisted by interlayer friction stir processing","authors":"Jingxun Wei ,&nbsp;Changshu He ,&nbsp;Mofan Qie ,&nbsp;Yunan Liu ,&nbsp;Hao Zhou ,&nbsp;Chenxi Kang ,&nbsp;Gaowu Qin","doi":"10.1016/j.addma.2024.104453","DOIUrl":"10.1016/j.addma.2024.104453","url":null,"abstract":"<div><div>The coarse grain size and poor mechanical properties of wire-arc directed energy deposition (DED) magnesium (Mg) alloys have hindered their wider application. In this study, the AZ91 Mg alloy component was fabricated by wire-arc DED assisted by interlayer friction stir processing (IFSP), and the highest strength and elongation were obtained in wire-arc DED AZ91 Mg alloy, which was mainly attributed to grain refinement, fragmentation/dispersion/dissolution of β-Mg₁₇Al₁₂ phase and heterogeneous microstructure in the IFSP stir zone (SZ). The formation of heterogeneous structure is caused by the fact that the refined grains in the SZ of the previous layer are affected by the thermal cycling of the subsequent additive manufacturing process, which led to different degrees of grain growth in different micro-zones within a SZ, and ultimately formed the microstructure characteristics with alternating distribution of coarse and fine grains. Compared with the wire-arc DED samples, the ultimate tensile strength of the wire-arc DED + IFSP samples in the perpendicular and parallel to the building directions increased from 284 and 264 MPa to 315 and 324 MPa, respectively. These values are comparable to those of their wrought counterparts, and the elongation increased by over 50 %. This study thus provides new insights into microstructure modification and performance enhancement of wire-arc DED fabricated Mg-alloys via a novel IFSP technique.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"94 ","pages":"Article 104453"},"PeriodicalIF":10.3,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142318868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Laser directed energy deposited eutectic high entropy alloy with tailored lamella structure via interlayer pause strategy","authors":"Zhouyang He ,&nbsp;Xingbao Qiu ,&nbsp;Xilei Bian ,&nbsp;Shiwei Wu ,&nbsp;Xiaolong Yu ,&nbsp;Chenwei Liu ,&nbsp;Zhen Hu ,&nbsp;Yuefei Jia ,&nbsp;Weisen Zheng ,&nbsp;Jinqiang Shi ,&nbsp;Zhibin Wu ,&nbsp;Xiaogang Lu ,&nbsp;Yandong Jia ,&nbsp;Gang Wang","doi":"10.1016/j.addma.2024.104471","DOIUrl":"10.1016/j.addma.2024.104471","url":null,"abstract":"<div><div>Eutectic high entropy alloys (EHEAs) have garnered significant attention due to their unique heterogeneous lamella structure, which imparts a desirable strength-ductility combination. Additive manufacturing (AM) techniques further exploit the advantageous properties of EHEAs through efficient fabrication and rapid heating/cooling processes. In this study, we fabricate near-fully dense and crack-free AlCoCrFeNi_2.1 EHEA samples with an alternating nano-scale eutectic lamellar structure composed of disordered face-centered cubic (FCC) and ordered B2 phases using the laser directed energy deposition (LDED) method. By using a novel and simple interlayer pause strategy, we have found that the eutectic lamellar structure can be significantly refined, achieving approximately 40% greater refinement compared to the case without interlayer pause. The optimized EHEA exhibits an exceptionally high strength of 1214 MPa and a sufficient uniform elongation of 16.3%, outperforming the non-interlayer-pause counterpart by 14% in strength and 47% in uniform elongation. The superior mechanical properties of the AlCoCrFeNi_2.1 EHEA are attributed to the synergistic effects of heterogeneous deformation-induced (HDI) strengthening and strain hardening mechanisms. Furthermore, the refined eutectic lamellar structure can effectively mitigate stress concentration mediated the formation of microcracks, thereby delaying fracture and maintaining plasticity. The interlayer pause strategy presented in this work offers a simple yet effective approach and valuable insights for the preparation of metallic materials with exceptional mechanical properties via LDED process.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"94 ","pages":"Article 104471"},"PeriodicalIF":10.3,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Additive manufacturing of high-strength low-alloy AISI 4340 steel with an optimal strength-ductility-toughness trade-off","authors":"Ju Yao,&nbsp;Qiyang Tan,&nbsp;Jeffrey Venezuela,&nbsp;Andrej Atrens,&nbsp;Ming-Xing Zhang","doi":"10.1016/j.addma.2024.104496","DOIUrl":"10.1016/j.addma.2024.104496","url":null,"abstract":"<div><div>Additive manufacturing (AM) has revolutionised steel part fabrication, yet not all steels are amenable to its unique solidification features, characterised by cyclic and rapid heating/cooling, and directional solidification. These conditions often result in challenges such as columnar grain formation, microstructural heterogeneity, and consequently, inferior mechanical performance, brittleness and severe anisotropy in particular. Recent studies have adopted inoculation or post-fabrication treatments to address this issue, but often entailing extra cost and processing time. This study aims to verify that some steels such as AISI 4340 steel are inherently compatible to AM, producing components that are innately robust and ready for use in the as-built state. The medium carbon content and low alloying element concentration enable AM processing to produce a uniform and refined bainite microstructure with minimal elemental segregation, avoiding the formation of unstable retained austenite. The high AM-processability of this steel is demonstrated by achieving high densification (&gt;99.9 %) across a broad processing window, which allows precise microstructural control via proper tunning the processing parameter modifications, inducing a transition from upper bainite to lower bainite dominance, to tailor mechanical properties for specific applications. The as AM-fabricated AISI 4340 steel exhibits a good combination of strength, ductility, and toughness, manifested by a yield strength range from 1240 to 1370 MPa, an ultimate tensile strength from 1360 to 1740 MPa, an elongation from 7 % to 14 %, and an impact toughness range of 11–44 J. The mechanical properties of the AM-fabricated 4340 steel are comparable to those of the wrought counterpart and superior to the majority of other AM-fabricated steels. This research reveals the high potential of AM to process high-strength low-alloy steels.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"94 ","pages":"Article 104496"},"PeriodicalIF":10.3,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Operando visualization of porous metal additive manufacturing with foaming agents through high-speed x-ray imaging","authors":"Chenxi Tian ,&nbsp;Jenniffer Bustillos ,&nbsp;Akane Wakai ,&nbsp;Ashlee Gabourel ,&nbsp;Samuel J. Clark ,&nbsp;Kamel Fezzaa ,&nbsp;Atieh Moridi","doi":"10.1016/j.addma.2024.104505","DOIUrl":"10.1016/j.addma.2024.104505","url":null,"abstract":"<div><div>Porous metals find extensive applications in soundproofing, filtration, catalysis, and energy-absorbing structures, thanks to their unique internal pore structure and high specific strength. In recent years, there has been an increasing interest in fabricating porous metals using additive manufacturing (AM), leveraging its unique advantages, including improved design freedom, spatial material control, and cost-effective small-batch production. In this study, we conducted pioneering operando visualization of AM porous metal using a laser powder bed fusion (L-PBF) setup combined with a high-speed synchrotron x-ray imaging system. Single track printing experiments using Ti6Al4V (Ti64) combined with titanium hydride (TiH₂) and sodium carbonate (Na₂CO₃) as foaming agents, with varying mixing ratios were performed under different processing conditions. The results elucidate the dynamic development of porosity formation. The average pore size is significantly influenced by the particle size of foaming agents when pore coalescence is absent. For all foaming agent content tested in the current study, the number of pores is found to be more sensitive to changes in laser power than in laser scanning speed. Increasing linear energy density (increasing laser power or reducing laser scanning speed) promotes the foaming agent activation thereby porosity formation. However, high linear energy density skews pore distribution towards the surface despite forming deeper melt pools. In addition, the impact of additional factors including foaming agent’s laser absorptivity and decomposition kinetics with respect to AM time scales should be carefully considered to avoid ineffective activation of foaming agents during the AM of porous metals.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"94 ","pages":"Article 104505"},"PeriodicalIF":10.3,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Corrigendum to “A trivariate T-spline based direct-slicing framework for support-free additive manufacturing” [Addit. Manuf. 65 (2023) 103446]","authors":"Bin Li ,&nbsp;Hongyao Shen ,&nbsp;Jianzhong Fu","doi":"10.1016/j.addma.2024.104493","DOIUrl":"10.1016/j.addma.2024.104493","url":null,"abstract":"","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"94 ","pages":"Article 104493"},"PeriodicalIF":10.3,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In-situ twin-wire additive manufacturing: Integrated fabrication of refractory medium entropy alloy, correlation between orientation and slip systems activation","authors":"Zhe Li ,&nbsp;Liang Wang ,&nbsp;Chen Liu ,&nbsp;Baoxian Su ,&nbsp;Binbin Wang ,&nbsp;Binqiang Li ,&nbsp;Weikun Zhang ,&nbsp;Qingda Zhang ,&nbsp;Zhiwen Li ,&nbsp;Liangshun Luo ,&nbsp;Ruirun Chen ,&nbsp;Jürgen Eckert ,&nbsp;Yanqing Su","doi":"10.1016/j.addma.2024.104454","DOIUrl":"10.1016/j.addma.2024.104454","url":null,"abstract":"<div><div>An innovative approach, i.e., twin-wire ‘co-pointed’ synergistic additive manufacturing implemented to create crack-free refractory medium entropy alloys eliminating costly powders, has been realized in this work. A self-designed twin-wire co-pointed strategy is suitable for near and high melting point elements. While the electron beam freeform fabrication (EBF³) process exhibits low porosity and defects and significant compositional homogeneity under a stabilized liquid bridge transfer mode, the mechanical properties and their dependence on orientation were studied in detail. Microstructural results of fabricated target non-equiatomic TiZrNbHf reveals a single-phase body centered cubic structure and typical columnar features with a &lt;100&gt;//building direction (BD) fiber texture. Tensile specimens taken from horizontal (&lt;100&gt;⊥tensile direction) and vertical (&lt;100&gt;//tensile direction) directions exhibit a comparable yield strength of 615.39 ± 7.88 MPa and 592.84 ± 5.95 MPa, with the failure elongations of 20.56 ± 1.00 % and 21.45 ± 0.72 %, respectively. In-situ EBSD characterization during tension reveals dislocation slip with {112} as the dominant plane as the only deformation mode. However the grain orientation affects the activation of slip systems, revealing non-Schmid factor behavior exists and determined by the grain boundary misorientation angle rather than the geometric compatibility factor. Horizontal grains enhanced the strength through a hard-oriented heterogeneous structure, while the vertical ones are prone to slip transfer on the same plane and wavy cross-slip to promote uniform deformation.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"94 ","pages":"Article 104454"},"PeriodicalIF":10.3,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single-photon-assisted two-photon polymerization","authors":"Buse Unlu ,&nbsp;Maria Isabel Álvarez-Castaño ,&nbsp;Antoine Boniface ,&nbsp;Ye Pu ,&nbsp;Christophe Moser","doi":"10.1016/j.addma.2024.104455","DOIUrl":"10.1016/j.addma.2024.104455","url":null,"abstract":"<div><div>Light-based additive manufacturing (AM) has revolutionized the fabrication of complex three-dimensional objects offering a cost-effective and high-speed alternative to traditional machining. Single-photon polymerization is a key process in this advancement, providing rapid printing time, albeit with limited resolution in the range of tens of micrometers. Two-photon polymerization provides sub-micrometer resolution but is accompanied by a tradeoff of prolonged printing times. We propose combining single- and two-photon absorption to benefit from the dual capabilities, allowing for faster printing time while maintaining high resolution. In this study, we employ a continuous-wave blue light source to pre-sensitize a photocurable resin by single-photon absorption followed by a tightly focused femtosecond laser beam to provide the required energy reaching the polymerization threshold for solidifying the resin through two-photon absorption. We first investigate the impact of pre-sensitization by blue light illumination followed by irradiation with a focused femtosecond laser beam and find that the voxel growth dynamics are markedly altered. Specifically, pre-sensitization by blue light lowers the polymerization threshold power of the femtosecond laser beam and increases the speed of voxel growth. We then exploit this effect by building a custom two-photon 3D printer in which the blue light pre-sensitization is created in a light-sheet configuration. We report successfully printed 3D objects for which the average femtosecond laser power was reduced by 28.6 % and the exposure time was reduced by a factor of two compared with polymerization performed only with the femtosecond laser beam. Additionally, a 63 % improvement in axial voxel size is attained through blue light-sheet pre-sensitization. Our theoretical analysis based on a diffusion-free model suggests that the mechanism of the pre-sensitization is oxygen depletion followed by a single-photon background latent polymerization.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"94 ","pages":"Article 104455"},"PeriodicalIF":10.3,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142328010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effective post-cleaning strategy for vat photopolymerization 3D printed complex-structured polymer-derived ceramics","authors":"Chongyu Long ,&nbsp;Long Jiang ,&nbsp;Shufeng Xiong ,&nbsp;Zhiyuan Liu ,&nbsp;Changyong Liu ,&nbsp;Zhangwei Chen","doi":"10.1016/j.addma.2024.104456","DOIUrl":"10.1016/j.addma.2024.104456","url":null,"abstract":"<div><div>Achieving ideal surface quality and high structural integrity of complex-structured polymer-derived ceramics manufactured by vat photopolymerization 3D printing not only depends on the high temperature pyrolysis processing, but also greatly relies on the complete removal of uncured resin on the surface and internal holes of the green bodies before pyrolysis. In this work, based on the characteristics of precursor resins and printed bodies, a novel cleaning strategy with excellent cleaning efficiency and the corresponding cleaning agent with good flowability, appropriate solubility, and strong volatility are proposed. The cleaning agent consists of two monomers, butyl acrylate (BA), and 1,6-hexanediol diacrylate (HDDA), which are components of the precursor resin, thereby avoiding chemical reactions between the cleaning agent and the printed bodies. Meanwhile, by adjusting their proportions, suitable solubility and volatility are achieved. Appropriate solubility ensures that under diluted conditions, it does not damage the cured resin, while strong volatility removes the diluted uncured resin in a short time. Additionally, good flowability enables thorough penetration into the internal holes to mix with and contact the uncured resin. This cleaning process achieves efficient and high-quality cleaning of ceramic precursor 3D printed bodies. The superiority of this strategy is confirmed by observing and characterizing the pyrolyzed samples. It achieves high surface quality, structural fidelity, and no crack defects, with 100 % opening of 150μm diameter holes, high through-hole rates, low surface roughness, and peak-to-valley height. In contrast, traditional cleaning processes have lower through-hole rates, higher roughness, and suffer from structural distortion and cracks. Thus, the proposed post-cleaning strategy provides a guidance on the design and selection of cleaning agents and methods for effective cleaning of these ceramic samples derived from similar ceramic precursors.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"94 ","pages":"Article 104456"},"PeriodicalIF":10.3,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142328013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tomographic projection optimization for volumetric additive manufacturing with general band constraint Lp-norm minimization","authors":"Chi Chung Li ,&nbsp;Joseph Toombs ,&nbsp;Hayden K. Taylor ,&nbsp;Thomas J. Wallin","doi":"10.1016/j.addma.2024.104447","DOIUrl":"10.1016/j.addma.2024.104447","url":null,"abstract":"<div><div>Tomographic volumetric additive manufacturing is a rapidly growing fabrication technology that enables rapid production of 3D objects through a single build step. In this process, the design of projections directly impacts geometric resolution, material properties, and manufacturing yield of the final printed part. Herein, we identify the hidden equivalent operations of three major existing projection optimization schemes and reformulate them into a general loss function where the optimization behavior can be systematically studied, and unique capabilities of the individual schemes can coalesce. The loss function formulation proposed in this study unified the optimization for binary and greyscale targets and generalized problem relaxation strategies with local tolerancing and weighting. Additionally, this formulation offers control on error sparsity and consistent dose response mapping throughout initialization, optimization, and evaluation. A parameter-sweep analysis in this study guides users in tuning optimization parameters for application-specific goals.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"94 ","pages":"Article 104447"},"PeriodicalIF":10.3,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A comprehensive support-free slicing method library for variable posture additive manufacturing","authors":"Zhengren Tong ,&nbsp;Xiaoling Yu ,&nbsp;Chen Yang ,&nbsp;Hongyao Shen","doi":"10.1016/j.addma.2024.104508","DOIUrl":"10.1016/j.addma.2024.104508","url":null,"abstract":"<div><div>Support-free slicing technology plays a critical role in additive manufacturing by reducing costs and simplifying post-processing. However, due to the complexity of geometric features, existing support-free slicing strategies often lack the necessary universality in industry. This paper proposes a method library comprising six basic support-free slicing methods to enhance the applicability and computational efficiency. The general methods in the library include facet-based methods and voxel-based methods, the former facilitates rapid slicing, while the latter enables the re-decomposition of complex structural parts. For parts that cannot be covered by general methods, customized methods are developed. These include constructing a support bridge for multi-direction slicing of overhanging regions in an arch model and extracting the optimal central axis for internal channels to achieve precise channel decomposition. Additionally, the methods in the library can be flexibly combined. By recognizing surface features and incorporating manual intervention, models can be decomposed into multiple sub-models, with the most computationally efficient method is matched to each sub-model. The layers and tool-paths of each sub-model are generated by the optimal method. Four typical models are deposited without any support in a five-axis printer to verify the feasibility of the proposed methods.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"94 ","pages":"Article 104508"},"PeriodicalIF":10.3,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}