Pub Date : 2026-01-25Epub Date: 2025-12-25DOI: 10.1016/j.addma.2025.105066
Dylan J. Balter , Colin McMillen , Alec Ewe , Jonathan Thomas , Samuel Silverman , Lalitha Parameswaran , Luis Fernando Velásquez-García , Emily Whiting , Steven Patterson , Hilmar Koerner , Keith A. Brown
Flexoelectricity is the electrical response that originates when insulating materials are subjected to a strain gradient. This effect is generally considered to be small but known to depend sensitively on material microstructure. This paper explores the hypothesis that the microstructure produced by additive manufacturing (AM) can strongly influence flexoelectricity. Surprisingly, it is found that minor changes to this microstructure produced using fused filament fabrication, a mainstream approach for additively manufacturing thermoplastics, can lead to enormous changes in the magnitude and polarity of the flexoelectric response of polylactic acid (PLA). To explain these changes, a layer dipole model (LDM) is proposed that connects the in-plane shear in each layer to the electrical polarization that it produces. This model explains three independent mechanisms that were identified and that collectively allow one to drastically increase the flexoelectric effect by 173 fold: (1) choosing printing settings to optimize the geometry of pores between extruded lines, (2) choosing the infill of each layer such that bending-induced strain produces productive in-plane shear stresses, and (3) post-deposition annealing of the printed material to increase its crystallinity. This understanding will enable future sensors in which the structural material is also responsible for electromechanical functionality.
{"title":"Giant flexoelectricity of additively manufactured polylactic acid","authors":"Dylan J. Balter , Colin McMillen , Alec Ewe , Jonathan Thomas , Samuel Silverman , Lalitha Parameswaran , Luis Fernando Velásquez-García , Emily Whiting , Steven Patterson , Hilmar Koerner , Keith A. Brown","doi":"10.1016/j.addma.2025.105066","DOIUrl":"10.1016/j.addma.2025.105066","url":null,"abstract":"<div><div>Flexoelectricity is the electrical response that originates when insulating materials are subjected to a strain gradient. This effect is generally considered to be small but known to depend sensitively on material microstructure. This paper explores the hypothesis that the microstructure produced by additive manufacturing (AM) can strongly influence flexoelectricity. Surprisingly, it is found that minor changes to this microstructure produced using fused filament fabrication, a mainstream approach for additively manufacturing thermoplastics, can lead to enormous changes in the magnitude and polarity of the flexoelectric response of polylactic acid (PLA). To explain these changes, a layer dipole model (LDM) is proposed that connects the in-plane shear in each layer to the electrical polarization that it produces. This model explains three independent mechanisms that were identified and that collectively allow one to drastically increase the flexoelectric effect by 173 fold: (1) choosing printing settings to optimize the geometry of pores between extruded lines, (2) choosing the infill of each layer such that bending-induced strain produces productive in-plane shear stresses, and (3) post-deposition annealing of the printed material to increase its crystallinity. This understanding will enable future sensors in which the structural material is also responsible for electromechanical functionality.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"116 ","pages":"Article 105066"},"PeriodicalIF":11.1,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923300","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}
Pub Date : 2026-01-25Epub Date: 2026-01-06DOI: 10.1016/j.addma.2026.105081
Xunrui Wang , Wenhua Tong , Yanru Shen , Sukun Tian , Suwei Dai , Hu Chen , Weiwei Li , Jinhong Li , Xiang Wang , Yuchun Sun
This work reports a volumetric stereolithography strategy, termed Dynamic Projection Lithography (DPL), for the rapid fabrication of thin-walled, freeform ceramic shell structures. By spatiotemporally programming a photon flux gradient and exploiting the synergistic photopolymerization of high-solid-loading ceramic slurries, DPL enables monolithic, support-free curing of thin-walled green bodies within an ultra-short single exposure cycle of 10 ± 0.5 s. In contrast to conventional layer-by-layer stereolithography, DPL integrates continuous three-dimensional energy-field modulation with curing kinetics, thereby eliminating interlayer interfaces and the associated defect sensitivity. Using complex-curvature zirconia dental veneers as a model, DPL achieves a volumetric fabrication rate of 129.57 mm3/h, representing an improvement of approximately two orders of magnitude over conventional layer-wise processes (∼ 2.58 mm3/h) and shortening the total manufacturing cycle from several hours to about 3.5 min. After sintering, the ceramic shells exhibit uniform, isotropic microstructures without discernible interlayer defects and show markedly enhanced mechanical performance. The combination of dynamic pulsed exposure and inverse geometric mapping ensures accurate reproduction of curved surfaces. These results demonstrate that DPL offers a highly efficient route for volumetric ceramic printing of ultra-thin freeform structures, with strong potential for biomedical and other high-value customized applications.
{"title":"Dynamic projection lithography for high-efficiency volumetric fabrication of thin-walled ceramics","authors":"Xunrui Wang , Wenhua Tong , Yanru Shen , Sukun Tian , Suwei Dai , Hu Chen , Weiwei Li , Jinhong Li , Xiang Wang , Yuchun Sun","doi":"10.1016/j.addma.2026.105081","DOIUrl":"10.1016/j.addma.2026.105081","url":null,"abstract":"<div><div>This work reports a volumetric stereolithography strategy, termed Dynamic Projection Lithography (DPL), for the rapid fabrication of thin-walled, freeform ceramic shell structures. By spatiotemporally programming a photon flux gradient and exploiting the synergistic photopolymerization of high-solid-loading ceramic slurries, DPL enables monolithic, support-free curing of thin-walled green bodies within an ultra-short single exposure cycle of 10 ± 0.5 s. In contrast to conventional layer-by-layer stereolithography, DPL integrates continuous three-dimensional energy-field modulation with curing kinetics, thereby eliminating interlayer interfaces and the associated defect sensitivity. Using complex-curvature zirconia dental veneers as a model, DPL achieves a volumetric fabrication rate of 129.57 mm<sup>3</sup>/h, representing an improvement of approximately two orders of magnitude over conventional layer-wise processes (∼ 2.58 mm<sup>3</sup>/h) and shortening the total manufacturing cycle from several hours to about 3.5 min. After sintering, the ceramic shells exhibit uniform, isotropic microstructures without discernible interlayer defects and show markedly enhanced mechanical performance. The combination of dynamic pulsed exposure and inverse geometric mapping ensures accurate reproduction of curved surfaces. These results demonstrate that DPL offers a highly efficient route for volumetric ceramic printing of ultra-thin freeform structures, with strong potential for biomedical and other high-value customized applications.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"116 ","pages":"Article 105081"},"PeriodicalIF":11.1,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923301","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}
Pub Date : 2026-01-05Epub Date: 2025-12-24DOI: 10.1016/j.addma.2025.105055
Natan Garrivier , Steven Van Petegem , Manuel Pouchon , Markus Strobl , Enrico Tosoratti , Adam Cretton , Ken Vidar Falch , Dario Ferreira Sanchez , Malgorzata Grazyna Makowska
Metal additive manufacturing is a promising route for producing complex, highly customized embedded structures for nuclear fusion environments, such as breeding blankets and divertors. These applications require steels with high thermomechanical stability and resistance to irradiation, yet AM processing often leads to undesired microstructural heterogeneities, including the formation of metastable phases. In this work, we investigate the formation and spatial distribution of retained austenite in Laser Powder Bed Fusion (PBF-LB/M) — processed ferritic–martensitic stainless steel (AISI 415) using multimodal synchrotron-based characterization. Micron-resolution 2D and 3D synchrotron X-ray Diffraction and X-ray Fluorescence mapping, combined with operando XRD during PBF-LB/M, reveal the presence of retained -phase in periodic mesostructures at concentrations up to 0.5 wt%, depending on scanning strategy. We demonstrated that this result, gained from volumetric measurements based on XRD scanning imaging, cannot be gathered by any surface-sensitive technique (e.g. EBSD) due to depth limitations and phase transformation artifacts during sample preparation. No correlation between -phase formation and elemental segregation was observed. Operando XRD measurements show that cooling rates critically affect phase evolution: wall-like geometries exhibit rapid cooling ( to K/s) and complete martensitic transformation, whereas bulk samples cool more slowly ( K/s), allowing up to 0.5 wt.% of -phase to be retained. These results demonstrate the strong influence of both scanning strategy and thermal history on phase stability in PBF-LB/M steels, supporting the qualification of AM-built components for nuclear applications.
{"title":"Multimodal synchrotron characterization of the formation and spatial distribution of retained austenite in PBF-LB/M-manufactured ferritic–martensitic steel","authors":"Natan Garrivier , Steven Van Petegem , Manuel Pouchon , Markus Strobl , Enrico Tosoratti , Adam Cretton , Ken Vidar Falch , Dario Ferreira Sanchez , Malgorzata Grazyna Makowska","doi":"10.1016/j.addma.2025.105055","DOIUrl":"10.1016/j.addma.2025.105055","url":null,"abstract":"<div><div>Metal additive manufacturing is a promising route for producing complex, highly customized embedded structures for nuclear fusion environments, such as breeding blankets and divertors. These applications require steels with high thermomechanical stability and resistance to irradiation, yet AM processing often leads to undesired microstructural heterogeneities, including the formation of metastable phases. In this work, we investigate the formation and spatial distribution of retained austenite in Laser Powder Bed Fusion (PBF-LB/M) — processed ferritic–martensitic stainless steel (AISI 415) using multimodal synchrotron-based characterization. Micron-resolution 2D and 3D synchrotron X-ray Diffraction and X-ray Fluorescence mapping, combined with operando XRD during PBF-LB/M, reveal the presence of retained <span><math><mi>γ</mi></math></span>-phase in periodic mesostructures at concentrations up to 0.5 wt%, depending on scanning strategy. We demonstrated that this result, gained from volumetric measurements based on <span><math><mi>μ</mi></math></span>XRD scanning imaging, cannot be gathered by any surface-sensitive technique (<em>e.g.</em> EBSD) due to depth limitations and phase transformation artifacts during sample preparation. No correlation between <span><math><mi>γ</mi></math></span>-phase formation and elemental segregation was observed. Operando XRD measurements show that cooling rates critically affect phase evolution: wall-like geometries exhibit rapid cooling (<span><math><mrow><mo>∼</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>5</mn></mrow></msup></mrow></math></span> to <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>6</mn></mrow></msup></mrow></math></span> K/s) and complete martensitic transformation, whereas bulk samples cool more slowly (<span><math><mrow><mo>∼</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></math></span> K/s), allowing up to 0.5 wt.% of <span><math><mi>γ</mi></math></span>-phase to be retained. These results demonstrate the strong influence of both scanning strategy and thermal history on phase stability in PBF-LB/M steels, supporting the qualification of AM-built components for nuclear applications.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105055"},"PeriodicalIF":11.1,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837477","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}
Laser powder bed fusion (L-PBF) of semi-crystalline polymers such as polyamide-12 (PA12) has found increasing use in various industrial applications. However, achieving high dimensional accuracy remains a significant challenge. Despite the seemingly straightforward layer-by-layer manufacturing concept, the L-PBF process involves complex thermal histories and strongly coupled multiphysics, making the evolution of stress and deformation mechanisms still not fully understood. To address this, a comprehensive three-dimensional thermo-mechanical modeling framework is developed to simulate the L-PBF process of PA12. The model for the first time incorporates transient heat transfer, phase transformation induced volumetric shrinkage, thermo-viscoelasticity, and a modified non-isothermal crystallization kinetics. To alleviate the computational burden of part-scale simulations, a dual-mesh strategy is employed to efficiently couple thermal and mechanical fields without compromising numerical accuracy, which also enables the framework to handle L-PBF simulations of arbitrarily complex three-dimensional geometries. Particular attention is paid to the role of mechanical and thermal boundary conditions. Specifically, the underlying powder bed is modeled as a fictitious viscous medium, providing support while permitting upward displacement. Additionally, a radiative heat loss boundary condition, which more closely approximates the actual physical process, is applied to the top powder surface. The incorporation of this radiation effect significantly enhances the crystallization rate and improves the agreement with experimentally measured warpage. The model is validated against experimental warpage data under various preheating temperatures. Furthermore, strain decoupling analysis for the first time reveals that displacement induced by phase transformation is approximately 10 times greater than that caused by thermal expansion, highlighting the dominant role of crystallization-induced shrinkage in warpage formation. Numerical tests also indicate that warpage is highly sensitive to the preheating target temperature of the PA12 powder bed, while the temperature of the newly recoated powder within the tested range has a limited effect. This work provides a predictive modeling foundation for future optimization of polymer L-PBF processes at part-scale, particularly in controlling deformation and improving dimensional accuracy.
{"title":"Deformation and stress evolution during laser powder bed fusion of semi-crystalline polyamide-12","authors":"Zhongfeng Xu , Wei Zhu , Lionel Freire , Noëlle Billon , Jean-Luc Bouvard , Yancheng Zhang","doi":"10.1016/j.addma.2025.105061","DOIUrl":"10.1016/j.addma.2025.105061","url":null,"abstract":"<div><div>Laser powder bed fusion (<span>L</span>-PBF) of semi-crystalline polymers such as polyamide-12 (PA12) has found increasing use in various industrial applications. However, achieving high dimensional accuracy remains a significant challenge. Despite the seemingly straightforward layer-by-layer manufacturing concept, the <span>L</span>-PBF process involves complex thermal histories and strongly coupled multiphysics, making the evolution of stress and deformation mechanisms still not fully understood. To address this, a comprehensive three-dimensional thermo-mechanical modeling framework is developed to simulate the <span>L</span>-PBF process of PA12. The model for the first time incorporates transient heat transfer, phase transformation induced volumetric shrinkage, thermo-viscoelasticity, and a modified non-isothermal crystallization kinetics. To alleviate the computational burden of part-scale simulations, a dual-mesh strategy is employed to efficiently couple thermal and mechanical fields without compromising numerical accuracy, which also enables the framework to handle <span>L</span>-PBF simulations of arbitrarily complex three-dimensional geometries. Particular attention is paid to the role of mechanical and thermal boundary conditions. Specifically, the underlying powder bed is modeled as a fictitious viscous medium, providing support while permitting upward displacement. Additionally, a radiative heat loss boundary condition, which more closely approximates the actual physical process, is applied to the top powder surface. The incorporation of this radiation effect significantly enhances the crystallization rate and improves the agreement with experimentally measured warpage. The model is validated against experimental warpage data under various preheating temperatures. Furthermore, strain decoupling analysis for the first time reveals that displacement induced by phase transformation is approximately 10 times greater than that caused by thermal expansion, highlighting the dominant role of crystallization-induced shrinkage in warpage formation. Numerical tests also indicate that warpage is highly sensitive to the preheating target temperature of the PA12 powder bed, while the temperature of the newly recoated powder within the tested range has a limited effect. This work provides a predictive modeling foundation for future optimization of polymer <span>L</span>-PBF processes at part-scale, particularly in controlling deformation and improving dimensional accuracy.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105061"},"PeriodicalIF":11.1,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837476","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}
Pub Date : 2026-01-05Epub Date: 2025-12-16DOI: 10.1016/j.addma.2025.105058
Haoze Wang , Yuheng Tian , Yuxin Li , Leiyi Qi , Peng Chen , Chunze Yan , Yusheng Shi
Incorporating glass fibers (GF) into LPBF-printed PEEK enhances its mechanical and high-temperature load-bearing capacity while preserving the polymer’s electromagnetic transparency, enabling use in demanding environments that require heat resistance, heavy loads and excellent electrical insulation. This study investigates the effects of fiber length and content on the processability and mechanical properties of GF-reinforced PEEK composites. The results demonstrate that increasing GF content expanded the sintering window by up to 18 % and raised thermal degradation temperatures, thereby improving LPBF processability. The tensile modulus peaked at 4.80 GPa (31 % increase at 20 wt% for 250-mesh fibers), while longer fibers (125-mesh) exhibited better flexural modulus (5.21 GPa, 43 % increase at 20 wt% for 125-mesh fibers), as longer fibers help prevent crack propagation and reduce defect impact in bending. The storage modulus increased with both fiber content and length, reaching up to 182 % higher at 50 °C for 125-mesh fibers at 20 wt%. The dielectric constants of the PEEK/GF composites ranged from 2.48 to 3.53, with low dielectric losses, indicating excellent stability across 1–40 GHz, confirming suitability for lightweight insulation and radome applications.
{"title":"Enhancing processability and performance of laser powder bed fusion-fabricated poly-ether-ether-ketone composites: Influence of glass fiber length and content","authors":"Haoze Wang , Yuheng Tian , Yuxin Li , Leiyi Qi , Peng Chen , Chunze Yan , Yusheng Shi","doi":"10.1016/j.addma.2025.105058","DOIUrl":"10.1016/j.addma.2025.105058","url":null,"abstract":"<div><div>Incorporating glass fibers (GF) into LPBF-printed PEEK enhances its mechanical and high-temperature load-bearing capacity while preserving the polymer’s electromagnetic transparency, enabling use in demanding environments that require heat resistance, heavy loads and excellent electrical insulation. This study investigates the effects of fiber length and content on the processability and mechanical properties of GF-reinforced PEEK composites. The results demonstrate that increasing GF content expanded the sintering window by up to 18 % and raised thermal degradation temperatures, thereby improving LPBF processability. The tensile modulus peaked at 4.80 GPa (31 % increase at 20 wt% for 250-mesh fibers), while longer fibers (125-mesh) exhibited better flexural modulus (5.21 GPa, 43 % increase at 20 wt% for 125-mesh fibers), as longer fibers help prevent crack propagation and reduce defect impact in bending. The storage modulus increased with both fiber content and length, reaching up to 182 % higher at 50 °C for 125-mesh fibers at 20 wt%. The dielectric constants of the PEEK/GF composites ranged from 2.48 to 3.53, with low dielectric losses, indicating excellent stability across 1–40 GHz, confirming suitability for lightweight insulation and radome applications.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105058"},"PeriodicalIF":11.1,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837748","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}
Pub Date : 2026-01-05Epub Date: 2025-12-08DOI: 10.1016/j.addma.2025.105047
Weiqin Tang , Zhenxuan Luo , Dayong Li , Yinghong Peng
Additive manufacturing (AM) technologies such as laser powder bed fusion (LPBF) enable the fabrication of complex components, yet intrinsic lack-of-fusion (LOF) defects significantly impair their fatigue performance due to their irregular morphologies. Multiscale physical-modeling struggles to predict fatigue strength scatter due to computational complexity and reliance on costly X-ray computed tomography (XCT)-based defect characterization. This study proposes a hybrid framework integrating multiscale simulation with deep learning to predict high-cycle fatigue (HCF) strength distributions in LPBF-fabricated AlSi10Mg alloys. A three-dimensional generative adversarial network (3D GAN) trained on XCT data is built to synthesize defects with real defect shapes, while a 3D convolutional neural network (3D CNN) with hybrid attention mechanisms is established to map the nonlinear relationship between defect features, loading conditions, and fatigue strengths. The multiscale simulation generates virtual datasets encompassing microstructure evolution, defect-induced stress concentrations, and fatigue responses. Results demonstrate that the CNN-GAN framework predicts fatigue strength distributions with 90 % accuracy, capturing experimental trends while exhibiting conservative deviations (≤7.7 %). The spatial-channel attention mechanism enhances feature extraction by focusing on defect edges and morphological criticalities. This work bridges the gap between LOF defects and fatigue prediction, offering a cost-effective and robust data-driven approach for reliability assessment of AM components.
{"title":"Predicting fatigue failure induced by lack-of-fusion defects in additive manufacturing: A synergistic multiscale simulation-deep learning framework","authors":"Weiqin Tang , Zhenxuan Luo , Dayong Li , Yinghong Peng","doi":"10.1016/j.addma.2025.105047","DOIUrl":"10.1016/j.addma.2025.105047","url":null,"abstract":"<div><div>Additive manufacturing (AM) technologies such as laser powder bed fusion (LPBF) enable the fabrication of complex components, yet intrinsic lack-of-fusion (LOF) defects significantly impair their fatigue performance due to their irregular morphologies. Multiscale physical-modeling struggles to predict fatigue strength scatter due to computational complexity and reliance on costly X-ray computed tomography (XCT)-based defect characterization. This study proposes a hybrid framework integrating multiscale simulation with deep learning to predict high-cycle fatigue (HCF) strength distributions in LPBF-fabricated AlSi10Mg alloys. A three-dimensional generative adversarial network (3D GAN) trained on XCT data is built to synthesize defects with real defect shapes, while a 3D convolutional neural network (3D CNN) with hybrid attention mechanisms is established to map the nonlinear relationship between defect features, loading conditions, and fatigue strengths. The multiscale simulation generates virtual datasets encompassing microstructure evolution, defect-induced stress concentrations, and fatigue responses. Results demonstrate that the CNN-GAN framework predicts fatigue strength distributions with 90 % accuracy, capturing experimental trends while exhibiting conservative deviations (≤7.7 %). The spatial-channel attention mechanism enhances feature extraction by focusing on defect edges and morphological criticalities. This work bridges the gap between LOF defects and fatigue prediction, offering a cost-effective and robust data-driven approach for reliability assessment of AM components.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105047"},"PeriodicalIF":11.1,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145735628","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}
Pub Date : 2026-01-05Epub Date: 2025-12-30DOI: 10.1016/j.addma.2025.105072
Victoria V. Beltran , Ruiqi Wang , Jun Young Hong , Youngsoo Jung , Sanghwan Moon , Do-Kyun Kwon , Jung-Kun Lee
The growing demand for rapid processing techniques in electronic materials has driven the development of efficient and scalable methods such as optically activated sintering by intense pulsed light (IPL) annealing. IPL quickly heat conductive metal films to 500 – 600 °C at which metal nanoparticles can be sintered. If the metal film consists of micro- and nano-size particles, sintered nanoparticles connect micro-size particles and enhance the electric conductivity of the film. As a millisecond-scale processing technique, IPL is especially suitable for use on sensitive substrates like polymers which can be easily damaged by conventional sintering of metal particles. This study, motivated by high-frequency packaging needs, focuses on improving DC electrical performance and surface morphology of copper electrodes on polyimide through a multi-step approach. First, computational simulations were performed to establish the damage threshold of the device. Second, IPL annealing was used to optically sinter screen-printed Cu films and enhance their conductivity. Third, Cu films were further processed using the infiltration of Ag MOD ink, cold rolling (CR), and IPL annealing, which decreased the porosity and surface roughness of Cu films. This integrated processing strategy yields conductive and smooth copper films on polyimide substrates. The resistivity of copper films is 8.32 × 10−6 Ω·cm which is slightly larger than that of bulk copper. The surface roughness is as low as 0.279 µm and the adhesion of the films on polyimide substrate is rated at 4B. These results show that the proposed method effectively improves the microstructure and DC electrical performance of Cu films and provides a promising basis for future studies to quantitatively assess high-frequency transmission performance.
{"title":"Enhancing the electric conductivity and surface smoothness of photosintered copper films on polyimide substrates","authors":"Victoria V. Beltran , Ruiqi Wang , Jun Young Hong , Youngsoo Jung , Sanghwan Moon , Do-Kyun Kwon , Jung-Kun Lee","doi":"10.1016/j.addma.2025.105072","DOIUrl":"10.1016/j.addma.2025.105072","url":null,"abstract":"<div><div>The growing demand for rapid processing techniques in electronic materials has driven the development of efficient and scalable methods such as optically activated sintering by intense pulsed light (IPL) annealing. IPL quickly heat conductive metal films to 500 – 600 °C at which metal nanoparticles can be sintered. If the metal film consists of micro- and nano-size particles, sintered nanoparticles connect micro-size particles and enhance the electric conductivity of the film. As a millisecond-scale processing technique, IPL is especially suitable for use on sensitive substrates like polymers which can be easily damaged by conventional sintering of metal particles. This study, motivated by high-frequency packaging needs, focuses on improving DC electrical performance and surface morphology of copper electrodes on polyimide through a multi-step approach. First, computational simulations were performed to establish the damage threshold of the device. Second, IPL annealing was used to optically sinter screen-printed Cu films and enhance their conductivity. Third, Cu films were further processed using the infiltration of Ag MOD ink, cold rolling (CR), and IPL annealing, which decreased the porosity and surface roughness of Cu films. This integrated processing strategy yields conductive and smooth copper films on polyimide substrates. The resistivity of copper films is 8.32 × 10<sup>−6</sup> Ω·cm which is slightly larger than that of bulk copper. The surface roughness is as low as 0.279 µm and the adhesion of the films on polyimide substrate is rated at 4B. These results show that the proposed method effectively improves the microstructure and DC electrical performance of Cu films and provides a promising basis for future studies to quantitatively assess high-frequency transmission performance.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105072"},"PeriodicalIF":11.1,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880747","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}
Pub Date : 2026-01-05Epub Date: 2025-12-30DOI: 10.1016/j.addma.2025.105071
Flavie Lebas, Alice Barrioulet, Ghislain Josse, Sylvain Marinel, Charles Manière
Pressureless of boron carbide (B4C) is very promising to produce high performance B4C parts useful in many applications. However, processing dense, complex-shaped components from coarse B4C powders remains particularly challenging due to coarsening-driven sintering and the very high temperatures required. In this work, direct ink writing (DIW) printable B4C suspensions were formulated using a tailored anionic carboxymethylcellulose binder, specifically designed to enable rapid, high height printing of coarse B4C powders. The recyclability of defective printed parts was also investigated. Conventional dilatometric sintering confirmed that coarse B4C powders undergo extensive grain coarsening and incomplete densification at 2200 °C, and sintering aids did not yield significant improvements. To overcome these limitations, ultra-high temperature pressureless spark plasma sintering (UHTP-SPS) was applied at ∼2350°C with rapid heating (200 °C/min), achieving near-full densification without additives. The resulting bimodal microstructure delivered high hardness values up to 33.6 GPa while maintaining flexural strength despite grain growth. Notably, recycled-route parts showed comparable properties to conventional ones, confirming the feasibility of reusing defective components. This study establishes a promising pathway for the cost-effective and sustainable fabrication of dense B4C components from coarse powders through rapid and high-temperature sintering.
{"title":"Formulation of direct ink writing suspensions from coarse and reused B4C powders with ultra-high-temperature pressureless SPS","authors":"Flavie Lebas, Alice Barrioulet, Ghislain Josse, Sylvain Marinel, Charles Manière","doi":"10.1016/j.addma.2025.105071","DOIUrl":"10.1016/j.addma.2025.105071","url":null,"abstract":"<div><div>Pressureless of boron carbide (B<sub>4</sub>C) is very promising to produce high performance B<sub>4</sub>C parts useful in many applications. However, processing dense, complex-shaped components from coarse B<sub>4</sub>C powders remains particularly challenging due to coarsening-driven sintering and the very high temperatures required. In this work, direct ink writing (DIW) printable B<sub>4</sub>C suspensions were formulated using a tailored anionic carboxymethylcellulose binder, specifically designed to enable rapid, high height printing of coarse B<sub>4</sub>C powders. The recyclability of defective printed parts was also investigated. Conventional dilatometric sintering confirmed that coarse B<sub>4</sub>C powders undergo extensive grain coarsening and incomplete densification at 2200 °C, and sintering aids did not yield significant improvements. To overcome these limitations, ultra-high temperature pressureless spark plasma sintering (UHTP-SPS) was applied at ∼2350°C with rapid heating (200 °C/min), achieving near-full densification without additives. The resulting bimodal microstructure delivered high hardness values up to 33.6 GPa while maintaining flexural strength despite grain growth. Notably, recycled-route parts showed comparable properties to conventional ones, confirming the feasibility of reusing defective components. This study establishes a promising pathway for the cost-effective and sustainable fabrication of dense B<sub>4</sub>C components from coarse powders through rapid and high-temperature sintering.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105071"},"PeriodicalIF":11.1,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880813","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}
Pub Date : 2026-01-05Epub Date: 2025-12-11DOI: 10.1016/j.addma.2025.105036
Nathaniel Wood , Nicholas Kirschbaum , Edwin Schwalbach , Sean Donegan , Andrew Gillman , Chinedum Okwudire
In situ heat treatment is a longstanding goal of laser powder bed fusion (L-PBF) process development because it would help mitigate build defects, improve throughput, and improve the printability of crack-prone materials. A primary barrier to these efforts is the L-PBF laser speed, which cannot move fast enough to achieve heat treatment through spot welding like in electron beam PBF. The state of the art (“Benchmark”) for achieving this heat treatment in a flexible geometry-agnostic way is performing extra laser passes over the build sequentially before fusing another layer. These Benchmark treatments succeed in transforming the microstructure, but at the cost of dramatically lengthened print times. We introduce an extension of the two-laser variant of the SmartScan algorithm, which leverages parallelized two-laser scans to perform the heat treatment while the layer is fused, with movements and powers optimized by physics-based models. We compare SmartScan against Benchmark scans for 3 heat treatment regimes, and compare both heat treatments against a standard slicer-derived toolpath with heuristically-chosen parameters (the “nominal scan”) on 316L stainless steel. We observe that SmartScan produces microstructures with features that correlate with superior mechanical properties, i.e. stronger, more isotropic, and better fatigue performance, given the manufactured steel is less strongly textured, with both smaller and more equiaxed grains that have lowered dislocation densities, and a higher relative density. Additionally, printing time is reduced by 77% with respect to the Benchmarks.
{"title":"Efficient multi-laser PBF microstructural tuning via physics-based feedforward control","authors":"Nathaniel Wood , Nicholas Kirschbaum , Edwin Schwalbach , Sean Donegan , Andrew Gillman , Chinedum Okwudire","doi":"10.1016/j.addma.2025.105036","DOIUrl":"10.1016/j.addma.2025.105036","url":null,"abstract":"<div><div><em>In situ</em> heat treatment is a longstanding goal of laser powder bed fusion (L-PBF) process development because it would help mitigate build defects, improve throughput, and improve the printability of crack-prone materials. A primary barrier to these efforts is the L-PBF laser speed, which cannot move fast enough to achieve heat treatment through spot welding like in electron beam PBF. The state of the art (“Benchmark”) for achieving this heat treatment in a flexible geometry-agnostic way is performing extra laser passes over the build sequentially before fusing another layer. These Benchmark treatments succeed in transforming the microstructure, but at the cost of dramatically lengthened print times. We introduce an extension of the two-laser variant of the <em>SmartScan</em> algorithm, which leverages parallelized two-laser scans to perform the heat treatment while the layer is fused, with movements and powers optimized by physics-based models. We compare SmartScan against Benchmark scans for 3 heat treatment regimes, and compare both heat treatments against a standard slicer-derived toolpath with heuristically-chosen parameters (the “nominal scan”) on 316L stainless steel. We observe that SmartScan produces microstructures with features that correlate with superior mechanical properties, i.e. stronger, more isotropic, and better fatigue performance, given the manufactured steel is less strongly textured, with both smaller and more equiaxed grains that have lowered dislocation densities, and a higher relative density. Additionally, printing time is reduced by 77% with respect to the Benchmarks.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105036"},"PeriodicalIF":11.1,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145788617","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}
Pub Date : 2026-01-05Epub Date: 2025-12-20DOI: 10.1016/j.addma.2025.105059
Zeqi Hu , Yongshuo She , Lin Hua , Kang Dong , Mingzhang Chen , Yitong Wang , Xunpeng Qin
The conventional planar layering paradigm of additive manufacturing (AM) has become a critical bottleneck, hindering the fabrication of high-performance components due to its inherent stair-stepping effect, mechanical anisotropy, and heavy reliance on support structures. Non-planar additive manufacturing (NPAM), by leveraging multi-axis motion systems and non-planar path planning, fundamentally overcomes these limitations, offering a transformative approach for the direct fabrication of parts with complex surfaces and optimized mechanical properties. This paper provides a comprehensive and systematic review of the latest research advancements in the NPAM field and innovatively establishes a core technology chain encompassing algorithm-system-process-quality. We delve into four key links: first, the non-planar slicing and path planning algorithms that form the technological core, covering strategies from support-free fabrication and performance enhancement to synergistic design with topology optimization; second, the multi-axis hardware systems that enable path execution, including robotic platforms, hybrid systems, specialized equipment, and their kinematic and dynamic control; third, the process physics and material behavior across polymers, composites, metals, ceramics, and functional inks; and finally, quality control to ensure manufacturing reliability, focusing on melt pool dynamics, geometric accuracy, microstructural evolution, and the crucial aspects of in-situ monitoring and closed-loop control. Furthermore, this paper systematically showcases the transformative applications of NPAM in aerospace, biomedical engineering, and conformal electronics. By elucidating the intrinsic connections between these technological links, this review aims to provide researchers with a structured knowledge framework, and prospect the future of intelligent design and manufacturing driven by artificial intelligence and digital twins.
{"title":"Non-planar additive manufacturing: A comprehensive review of path planning, system integration, process control, and applications","authors":"Zeqi Hu , Yongshuo She , Lin Hua , Kang Dong , Mingzhang Chen , Yitong Wang , Xunpeng Qin","doi":"10.1016/j.addma.2025.105059","DOIUrl":"10.1016/j.addma.2025.105059","url":null,"abstract":"<div><div>The conventional planar layering paradigm of additive manufacturing (AM) has become a critical bottleneck, hindering the fabrication of high-performance components due to its inherent stair-stepping effect, mechanical anisotropy, and heavy reliance on support structures. Non-planar additive manufacturing (NPAM), by leveraging multi-axis motion systems and non-planar path planning, fundamentally overcomes these limitations, offering a transformative approach for the direct fabrication of parts with complex surfaces and optimized mechanical properties. This paper provides a comprehensive and systematic review of the latest research advancements in the NPAM field and innovatively establishes a core technology chain encompassing algorithm-system-process-quality. We delve into four key links: first, the non-planar slicing and path planning algorithms that form the technological core, covering strategies from support-free fabrication and performance enhancement to synergistic design with topology optimization; second, the multi-axis hardware systems that enable path execution, including robotic platforms, hybrid systems, specialized equipment, and their kinematic and dynamic control; third, the process physics and material behavior across polymers, composites, metals, ceramics, and functional inks; and finally, quality control to ensure manufacturing reliability, focusing on melt pool dynamics, geometric accuracy, microstructural evolution, and the crucial aspects of in-situ monitoring and closed-loop control. Furthermore, this paper systematically showcases the transformative applications of NPAM in aerospace, biomedical engineering, and conformal electronics. By elucidating the intrinsic connections between these technological links, this review aims to provide researchers with a structured knowledge framework, and prospect the future of intelligent design and manufacturing driven by artificial intelligence and digital twins.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"115 ","pages":"Article 105059"},"PeriodicalIF":11.1,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837746","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}
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