Pub Date : 2026-04-01Epub Date: 2026-01-09DOI: 10.1016/j.addlet.2026.100355
Peter Pak , Achuth Chandrasekhar , Amir Barati Farimani
Agentic systems enable the intelligent use of research tooling, augmenting a researcher’s ability to investigate and propose novel solutions to existing problems. Within Additive Manufacturing (AM), alloy selection and evaluation remains a complex challenge, often requiring expertise in the various domains of materials science, thermodynamic simulations, and experimental analysis. Large Language Model (LLM) enabled agents can facilitate this endeavor by utilizing their extensive knowledge base to dispatch tool calls via Model Context Protocol (MCP) to perform actions such as thermophysical property diagram calculations and lack of fusion process map generation. In addition, the multi-agent system can effectively reason through complex user prompts and provide analysis on the lack of fusion process window of common alloys such as SS316L and IN718 along with proposed composition variants of known alloys. These agents can dynamically adjust their task trajectory to the outcomes of tool call results, effectively enabling autonomous decision-making in practical environments. This work aims to showcase the benefits of adopting a LLM enabled multi-agent system to automate and accelerate the task of evaluating proposed additive manufacturing alloys, both novel and known.
{"title":"Agentic additive manufacturing alloy evaluation","authors":"Peter Pak , Achuth Chandrasekhar , Amir Barati Farimani","doi":"10.1016/j.addlet.2026.100355","DOIUrl":"10.1016/j.addlet.2026.100355","url":null,"abstract":"<div><div>Agentic systems enable the intelligent use of research tooling, augmenting a researcher’s ability to investigate and propose novel solutions to existing problems. Within Additive Manufacturing (AM), alloy selection and evaluation remains a complex challenge, often requiring expertise in the various domains of materials science, thermodynamic simulations, and experimental analysis. Large Language Model (LLM) enabled agents can facilitate this endeavor by utilizing their extensive knowledge base to dispatch tool calls via Model Context Protocol (MCP) to perform actions such as thermophysical property diagram calculations and lack of fusion process map generation. In addition, the multi-agent system can effectively reason through complex user prompts and provide analysis on the lack of fusion process window of common alloys such as SS316L and IN718 along with proposed composition variants of known alloys. These agents can dynamically adjust their task trajectory to the outcomes of tool call results, effectively enabling autonomous decision-making in practical environments. This work aims to showcase the benefits of adopting a LLM enabled multi-agent system to automate and accelerate the task of evaluating proposed additive manufacturing alloys, both novel and known.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"17 ","pages":"Article 100355"},"PeriodicalIF":4.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-06DOI: 10.1016/j.addlet.2026.100354
Shadman Tahsin Nabil , Alfonso Fernandez , Francisco Medina , Ralph Felice , James P. Carney , César A. Terrazas-Nájera
Highly dynamic conditions experienced during metals processing using powder bed fusion (PBF) additive manufacturing (AM) arise from the interaction of multiple process variables. Chiefly amongst them is the energy source-material interaction, which results in abrupt, temporally changing thermal conditions at the melt-pool. The absorption of the energy from the source by the powder bed is complicated complex because this interaction is highly dynamic and occluded by process emissions including the plasma plume and spatter. Typical approaches for measuring absorption conditions have relied on intricate ex situ setups requiring extensive sample preparation. This work involved approximating the absorptivity for a nickel-base material from in situ observations made using a multi-wavelength (MW) pyrometry sensor, while processing using electron-beam based powder bed fusion (PBF-EB/M). The prediction step involved fitting the spectral data captured by the MW sensor to then extrapolate values to shorter wavelengths. The approximation was done for wavelengths that are relevant for the PBF-LB/M process, where absorptivity of the laser energy is paramount. The results obtained provide a window into the behavior of this material as it transitions from powder to molten state, showing that the absorptivity substantially decreases (∼60% reduction) as the powder material changes phase induced by incipient melting. While this work focuses on a single material, the approach presented can help characterize the absorptivity of other materials employed in PBF. This work helps support both experimental and modeling efforts that are helpful to increase our understanding and practice of fusion-based AM processes, and other manufacturing techniques.
{"title":"Approximation of absorptivity conditions for Inconel 625 from in situ radiation thermometry measurements in electron beam powder bed fusion","authors":"Shadman Tahsin Nabil , Alfonso Fernandez , Francisco Medina , Ralph Felice , James P. Carney , César A. Terrazas-Nájera","doi":"10.1016/j.addlet.2026.100354","DOIUrl":"10.1016/j.addlet.2026.100354","url":null,"abstract":"<div><div>Highly dynamic conditions experienced during metals processing using powder bed fusion (PBF) additive manufacturing (AM) arise from the interaction of multiple process variables. Chiefly amongst them is the energy source-material interaction, which results in abrupt, temporally changing thermal conditions at the melt-pool. The absorption of the energy from the source by the powder bed is complicated complex because this interaction is highly dynamic and occluded by process emissions including the plasma plume and spatter. Typical approaches for measuring absorption conditions have relied on intricate <em>ex situ</em> setups requiring extensive sample preparation. This work involved approximating the absorptivity for a nickel-base material from in situ observations made using a multi-wavelength (MW) pyrometry sensor, while processing using electron-beam based powder bed fusion (PBF-EB/M). The prediction step involved fitting the spectral data captured by the MW sensor to then extrapolate values to shorter wavelengths. The approximation was done for wavelengths that are relevant for the PBF-LB/M process, where absorptivity of the laser energy is paramount. The results obtained provide a window into the behavior of this material as it transitions from powder to molten state, showing that the absorptivity substantially decreases (∼60% reduction) as the powder material changes phase induced by incipient melting. While this work focuses on a single material, the approach presented can help characterize the absorptivity of other materials employed in PBF. This work helps support both experimental and modeling efforts that are helpful to increase our understanding and practice of fusion-based AM processes, and other manufacturing techniques.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"17 ","pages":"Article 100354"},"PeriodicalIF":4.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145929169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-12-31DOI: 10.1016/j.addlet.2025.100353
Christian Maximilian Hechtl , Maximilian Dahlenburg , Freek Bos , Thomas Kränkel , Christoph Gehlen
3D concrete printing (3DCP) enables layerwise fabrication with digital control, offering geometric freedom and material efficiency. However, conventional pump-based 3DCP is constrained by conflicting material requirements, namely sufficient workability for pumping and extrusion versus sufficient resistance to flow and early-age structural build-up for buildability after deposition. This paper introduces Adaptive-Binder-Aggregate Mixing (ABAM), a process concept that avoids long-distance pumping of an aggregate-rich printable cementitious composite (PCC), which can be critical for porous lightweight aggregates and can limit feasible aggregate size and volume fraction. Instead, a pumpable cementitious compound (CC) without aggregates is prepared in the stationary environment and conveyed to the end-effector, where aggregates are stored and incorporated near the nozzle to form the PCC shortly before deposition. The process enables functional material gradation by switching aggregate type during printing, allowing spatial property tailoring within a monolithic element. A prototype implementation is presented together with an initial feasibility demonstration.
{"title":"Adaptive-binder-aggregate mixing (ABAM): Concept for extrusion-based multi-material 3D concrete printing","authors":"Christian Maximilian Hechtl , Maximilian Dahlenburg , Freek Bos , Thomas Kränkel , Christoph Gehlen","doi":"10.1016/j.addlet.2025.100353","DOIUrl":"10.1016/j.addlet.2025.100353","url":null,"abstract":"<div><div>3D concrete printing (3DCP) enables layerwise fabrication with digital control, offering geometric freedom and material efficiency. However, conventional pump-based 3DCP is constrained by conflicting material requirements, namely sufficient workability for pumping and extrusion versus sufficient resistance to flow and early-age structural build-up for buildability after deposition. This paper introduces Adaptive-Binder-Aggregate Mixing (ABAM), a process concept that avoids long-distance pumping of an aggregate-rich printable cementitious composite (PCC), which can be critical for porous lightweight aggregates and can limit feasible aggregate size and volume fraction. Instead, a pumpable cementitious compound (CC) without aggregates is prepared in the stationary environment and conveyed to the end-effector, where aggregates are stored and incorporated near the nozzle to form the PCC shortly before deposition. The process enables functional material gradation by switching aggregate type during printing, allowing spatial property tailoring within a monolithic element. A prototype implementation is presented together with an initial feasibility demonstration.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"17 ","pages":"Article 100353"},"PeriodicalIF":4.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2025-12-02DOI: 10.1016/j.addlet.2025.100343
Adam G. Stevens , Vanshika Singh , Rangasayee Kannan , David Hebble , Sarah Graham , Paritosh Mhatre , Kevin Zinn , Christopher Masuo , William Carter , Jesse Heineman , Andres Marquez Rossy , Alexandra B. Shanafield , Charles Savage , Alex Roschli , Brian Hicks , Peeyush Nandwana , S.S. Babu , Brian K. Post
Electroslag Additive Manufacturing (ESAM), a new high-throughput additive manufacturing (AM) method that combines Electroslag Strip Cladding (ESC) and wire arc AM (WAAM) is introduced. This combination enables the high deposition rate of ESC (more than 20 kg/h with a 60 mm strip electrode) to benefit from the precise geometric control of WAAM. As a precursor to ESAM, the ESC process is investigated in an AM context independently by evaluating both direct and staggered bead-stacking strategies and analyzing the microstructural and mechanical properties of each. This is followed by an ESAM demonstration producing an annular geometry by pairing ESC with gas tungsten arc welding (GTAW), wherein GTAW is utilized to construct annular walls that are subsequently infilled via ESC. The microstructure and mechanical properties of ESC-only AM are compared with that of the ESAM method and it is shown that printed integral retaining walls do not impact the resulting mechanical properties of ESAM. Furthermore, results indicate that ESAM-produced Alloy 625 parts exhibit tensile properties on par with cast counterparts, supporting the method’s scalability to components exceeding one metric ton, and possibly making ESAM a viable future manufacturing approach for competitive production of large-scale components currently manufactured by casting and forging.
{"title":"Electroslag additive manufacturing: A pathway for high throughput near net shape production","authors":"Adam G. Stevens , Vanshika Singh , Rangasayee Kannan , David Hebble , Sarah Graham , Paritosh Mhatre , Kevin Zinn , Christopher Masuo , William Carter , Jesse Heineman , Andres Marquez Rossy , Alexandra B. Shanafield , Charles Savage , Alex Roschli , Brian Hicks , Peeyush Nandwana , S.S. Babu , Brian K. Post","doi":"10.1016/j.addlet.2025.100343","DOIUrl":"10.1016/j.addlet.2025.100343","url":null,"abstract":"<div><div>Electroslag Additive Manufacturing (ESAM), a new high-throughput additive manufacturing (AM) method that combines Electroslag Strip Cladding (ESC) and wire arc AM (WAAM) is introduced. This combination enables the high deposition rate of ESC (more than 20 kg/h with a 60 mm strip electrode) to benefit from the precise geometric control of WAAM. As a precursor to ESAM, the ESC process is investigated in an AM context independently by evaluating both direct and staggered bead-stacking strategies and analyzing the microstructural and mechanical properties of each. This is followed by an ESAM demonstration producing an annular geometry by pairing ESC with gas tungsten arc welding (GTAW), wherein GTAW is utilized to construct annular walls that are subsequently infilled via ESC. The microstructure and mechanical properties of ESC-only AM are compared with that of the ESAM method and it is shown that printed integral retaining walls do not impact the resulting mechanical properties of ESAM. Furthermore, results indicate that ESAM-produced Alloy 625 parts exhibit tensile properties on par with cast counterparts, supporting the method’s scalability to components exceeding one metric ton, and possibly making ESAM a viable future manufacturing approach for competitive production of large-scale components currently manufactured by casting and forging.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"17 ","pages":"Article 100343"},"PeriodicalIF":4.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145898130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-14DOI: 10.1016/j.addlet.2026.100366
Mahdi Alishavandi, Rahmi Ünal, Metin U. Salamci
Melt pool instabilities limit the reliability of additive manufacturing. Here, we demonstrate that a minimal Buckingham- framework, supplemented by a normalized enthalpy (NE) metric, consolidates process outcomes across heat source settings (power, speed, spot) and material properties. IN738LC was processed on an EOS M290; single-track and bulk responses, melt pool geometric features, part relative density (), and areal roughness parameters and , were quantified and subsequently mapped onto compact NE-dimensionless number spaces after the normalized-enthalpy metric had been calibrated using an effective absorptivity inferred from the measured melt pool depth. The recoil number cleanly delineates modes: (conductionstable keyhole) maintains with low , whereas –5 marks an unstable keyhole with spatter and porosity. Within this map, favorable transport balances are , , small and not-too-small , and ; external convection remains negligible (). Rather than VED, we advocate working directly in -space —to define, compare, and transfer qualifiable process windows across machines and alloys.
{"title":"A Buckingham-Pi dimensionless analysis for melt pool stability and defect prediction in additive manufacturing","authors":"Mahdi Alishavandi, Rahmi Ünal, Metin U. Salamci","doi":"10.1016/j.addlet.2026.100366","DOIUrl":"10.1016/j.addlet.2026.100366","url":null,"abstract":"<div><div>Melt pool instabilities limit the reliability of additive manufacturing. Here, we demonstrate that a minimal Buckingham-<span><math><mi>π</mi></math></span> framework, supplemented by a normalized enthalpy (NE) metric, consolidates process outcomes across heat source settings (power, speed, spot) and material properties. IN738LC was processed on an EOS M290; single-track and bulk responses, melt pool geometric features, part relative density (<span><math><msup><mrow><mi>ρ</mi></mrow><mrow><mo>∗</mo></mrow></msup></math></span>), and areal roughness parameters <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>a</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>z</mi></mrow></msub></math></span>, were quantified and subsequently mapped onto compact NE-dimensionless number spaces after the normalized-enthalpy metric had been calibrated using an effective absorptivity inferred from the measured melt pool depth. The recoil number cleanly delineates modes: <span><math><mrow><mi>Recoil</mi><mspace></mspace><mo>≲</mo><mspace></mspace><mn>2</mn></mrow></math></span> (conduction<span><math><mo>→</mo></math></span>stable keyhole) maintains <span><math><mrow><msup><mrow><mi>ρ</mi></mrow><mrow><mo>∗</mo></mrow></msup><mspace></mspace><mo>≳</mo><mspace></mspace><mn>99</mn><mtext>%</mtext></mrow></math></span> with low <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>a</mi></mrow></msub></math></span>, whereas <span><math><mrow><mi>Recoil</mi><mspace></mspace><mo>≳</mo><mspace></mspace><mn>4</mn></mrow></math></span>–5 marks an unstable keyhole with spatter and porosity. Within this map, favorable transport balances are <span><math><mrow><mi>Re</mi><mspace></mspace><mo>≲</mo><mspace></mspace><mn>100</mn></mrow></math></span>, <span><math><mrow><mi>We</mi><mspace></mspace><mo><</mo><mspace></mspace><mn>1</mn></mrow></math></span>, small <span><math><mi>Ca</mi></math></span> and not-too-small <span><math><mi>Oh</mi></math></span>, and <span><math><mrow><mi>Fo</mi><mspace></mspace><mo>></mo><mspace></mspace><mn>0</mn><mo>.</mo><mn>1</mn></mrow></math></span>; external convection remains negligible (<span><math><mrow><mi>Nu</mi><mspace></mspace><mo>≪</mo><mspace></mspace><mn>1</mn></mrow></math></span>). Rather than VED, we advocate working directly in <span><math><mi>Π</mi></math></span>-space <span><math><mrow><mo>(</mo><mi>NE</mi><mo>,</mo><mi>Recoil</mi><mo>,</mo><mi>Re</mi><mo>,</mo><mi>We</mi><mo>,</mo><mi>Ca</mi><mo>,</mo><mi>Oh</mi><mo>,</mo><mi>Fo</mi><mo>,</mo><mi>Nu</mi><mo>)</mo></mrow></math></span>—to define, compare, and transfer qualifiable process windows across machines and alloys.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"17 ","pages":"Article 100366"},"PeriodicalIF":4.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147384995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-02DOI: 10.1016/j.addlet.2026.100363
Abhinav Anand , Ondřej Kovářík , Pavel Ctibor , Zahra Arabgol , Levke Wiehler , Frank Gärtner , Thomas Klassen , Jan Cizek
Pure iron powder combines excellent plastic deformability under a high-velocity impact with high magnetizability and permeability, making it an economical candidate for cold spray additive manufacturing (CSAM) and repairs in magnetic applications. This work explores the fracture mechanics and electromagnetic (EM) properties of CSAM pure iron deposited using cheaper nitrogen as the process gas at temperatures of 900 °C and 1000 °C, achieving relative densities of 97.3 % and 98.0 %, respectively. The deposits exhibited an ultimate tensile strength greater than 250 MPa and elongation to fracture of less than 0.3 %, a behavior consistent with the characteristic results of as-sprayed CSAM deposits. The fatigue crack growth rate analyses showed the propagation being faster than in wrought iron through different mechanisms: trans-particle crack propagation near the threshold stress intensity factor, and inter-particle decohesion at higher loads. The EM testing indicated that CSAM pure iron saturated at a lower induction and had lower permeability than wrought low-carbon steel, while its coercivity and hysteresis losses were higher, and electrical resistivity was similar. Despite the lower mechanical and magnetic performance, CSAM pure iron or similarly deformable ferritic alloys can meet the requirements for low-field, low-frequency, or direct-current applications, and provide a route for direct near-net-shape additive manufacturing or in-situ repair of magnetic components without scraping existing parts.
{"title":"Cold spray additively manufactured pure iron for magnetic applications","authors":"Abhinav Anand , Ondřej Kovářík , Pavel Ctibor , Zahra Arabgol , Levke Wiehler , Frank Gärtner , Thomas Klassen , Jan Cizek","doi":"10.1016/j.addlet.2026.100363","DOIUrl":"10.1016/j.addlet.2026.100363","url":null,"abstract":"<div><div>Pure iron powder combines excellent plastic deformability under a high-velocity impact with high magnetizability and permeability, making it an economical candidate for cold spray additive manufacturing (CSAM) and repairs in magnetic applications. This work explores the fracture mechanics and electromagnetic (EM) properties of CSAM pure iron deposited using cheaper nitrogen as the process gas at temperatures of 900 °C and 1000 °C, achieving relative densities of 97.3 % and 98.0 %, respectively. The deposits exhibited an ultimate tensile strength greater than 250 MPa and elongation to fracture of less than 0.3 %, a behavior consistent with the characteristic results of as-sprayed CSAM deposits. The fatigue crack growth rate analyses showed the propagation being faster than in wrought iron through different mechanisms: trans-particle crack propagation near the threshold stress intensity factor, and inter-particle decohesion at higher loads. The EM testing indicated that CSAM pure iron saturated at a lower induction and had lower permeability than wrought low-carbon steel, while its coercivity and hysteresis losses were higher, and electrical resistivity was similar. Despite the lower mechanical and magnetic performance, CSAM pure iron or similarly deformable ferritic alloys can meet the requirements for low-field, low-frequency, or direct-current applications, and provide a route for direct near-net-shape additive manufacturing or in-situ repair of magnetic components without scraping existing parts.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"17 ","pages":"Article 100363"},"PeriodicalIF":4.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-17DOI: 10.1016/j.addlet.2026.100357
Irtaza Razvi , Kareem Tawil , Chris Chunbin , David Trauernicht , Daniel Cormier , Zipeng Guo , Denis Cormier
Molten metal droplet jetting (MMJ) is an emerging metal additive manufacturing (AM) technology that can use low-cost wire, rod, or even ingot feedstock material. This paper describes the architecture and preliminary implementation of what is believed to be among the first demonstrations of MMJ with a multi-nozzle array that is akin to inkjet printing using molten metal as the ink. A multi-nozzle printhead with a communal reservoir and three piezoelectric actuator pistons is presented. The drive waveforms for each nozzle are independently addressable, thus enabling precise control over drop placement for raster printing of arbitrary layer shapes. A jetting strategy is described in which variable track spacing is achieved by altering the yaw angle of the printhead. This yaw angle method allows printed row pitches that are less than or equal to the nozzle pitch. The printhead and build strategy are applied to demonstrate feasibility of the method with single and multi-layer test sample geometries. The influence of these initial results on future multi-nozzle systems is discussed.
{"title":"Multi-nozzle molten metal droplet jetting","authors":"Irtaza Razvi , Kareem Tawil , Chris Chunbin , David Trauernicht , Daniel Cormier , Zipeng Guo , Denis Cormier","doi":"10.1016/j.addlet.2026.100357","DOIUrl":"10.1016/j.addlet.2026.100357","url":null,"abstract":"<div><div>Molten metal droplet jetting (MMJ) is an emerging metal additive manufacturing (AM) technology that can use low-cost wire, rod, or even ingot feedstock material. This paper describes the architecture and preliminary implementation of what is believed to be among the first demonstrations of MMJ with a multi-nozzle array that is akin to inkjet printing using molten metal as the ink. A multi-nozzle printhead with a communal reservoir and three piezoelectric actuator pistons is presented. The drive waveforms for each nozzle are independently addressable, thus enabling precise control over drop placement for raster printing of arbitrary layer shapes. A jetting strategy is described in which variable track spacing is achieved by altering the yaw angle of the printhead. This yaw angle method allows printed row pitches that are less than or equal to the nozzle pitch. The printhead and build strategy are applied to demonstrate feasibility of the method with single and multi-layer test sample geometries. The influence of these initial results on future multi-nozzle systems is discussed.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"17 ","pages":"Article 100357"},"PeriodicalIF":4.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-02DOI: 10.1016/j.addlet.2026.100365
Jingshan Liu , Ge Zhou , Wenjingzi Wang , Haoyu Zhang , Bingqian Jin , Lijia Chen , Xin Liu , Qi Shi , Ximin Zang
In view of the problem of coordinated control of powder particle size distribution and surface quality during the preparation process of NiTi shape memory alloy 3D printing special metal powder EIGA method, a novel multi-stage-controlled gas atomization method is presented in this study to address the coordinated control of powder particle size distribution and surface quality. The process experiment, comprehensive powder performance test, and characterization of composition and microstructure were carried out, along with the construction of a theoretical model and mechanism research of metal droplet breakup and rapid solidification under multi-field coupling control. The results show that for the breaking behavior of metal droplets, the multi-stage-controlled gas atomization method can maximize the surface energy of metal droplets, which is beneficial to droplet breaking. For the spheroidization and solidification behavior, under the multi-stage-controlled gas atomization pressure, by adjusting the heating power and the feed rate of the bar, the mismatch between the solidification and spheroidization behavior of the droplets can be effectively improved (Ф = tspheroidization / tsolidification ≈ 1). The sphericity and surface quality of the powder are improved. The NiTi alloy powder prepared by this method retained its main elements. The maximum increments of O and N elements are 310 ppm and 70 ppm, and D90 is 50.3 μm. The powder sphericity is good, significantly reducing the number of hollow and satellite powders. This method plays a vital role in improving the application of NiTi alloy powder in 3D printing.
{"title":"Metal droplet breakup and rapid solidification behavior under multi-stage-controlled atomization process: NiTi alloys 3D printing special powder preparation","authors":"Jingshan Liu , Ge Zhou , Wenjingzi Wang , Haoyu Zhang , Bingqian Jin , Lijia Chen , Xin Liu , Qi Shi , Ximin Zang","doi":"10.1016/j.addlet.2026.100365","DOIUrl":"10.1016/j.addlet.2026.100365","url":null,"abstract":"<div><div>In view of the problem of coordinated control of powder particle size distribution and surface quality during the preparation process of NiTi shape memory alloy 3D printing special metal powder EIGA method, a novel multi-stage-controlled gas atomization method is presented in this study to address the coordinated control of powder particle size distribution and surface quality. The process experiment, comprehensive powder performance test, and characterization of composition and microstructure were carried out, along with the construction of a theoretical model and mechanism research of metal droplet breakup and rapid solidification under multi-field coupling control. The results show that for the breaking behavior of metal droplets, the multi-stage-controlled gas atomization method can maximize the surface energy of metal droplets, which is beneficial to droplet breaking. For the spheroidization and solidification behavior, under the multi-stage-controlled gas atomization pressure, by adjusting the heating power and the feed rate of the bar, the mismatch between the solidification and spheroidization behavior of the droplets can be effectively improved (Ф = t<sub>spheroidization</sub> / t<sub>solidification</sub> ≈ 1). The sphericity and surface quality of the powder are improved. The NiTi alloy powder prepared by this method retained its main elements. The maximum increments of O and N elements are 310 ppm and 70 ppm, and D<sub>90</sub> is 50.3 μm. The powder sphericity is good, significantly reducing the number of hollow and satellite powders. This method plays a vital role in improving the application of NiTi alloy powder in 3D printing.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"17 ","pages":"Article 100365"},"PeriodicalIF":4.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147384993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-20DOI: 10.1016/j.addlet.2026.100369
C. Garrett Campbell , Camden Chatham , Samantha J. (Lindholm) Knight , E. Cade Willis , Andrew P. Rhodes
Polymeric material options for powder bed fusion (PBF) additive manufacturing (AM) techniques are typically limited to semicrystalline thermoplastics with large differences between their melting and recrystallization temperatures. Amorphous thermoplastics like polyetherimides (PEIs) are desired in certain applications but cannot be effectively processed by PBF due to their lack of crystallinity. Herein, we present a new solvent processing method which induces crystallinity in a particular grade of PEI, Ultem CRS5011, thus enabling its processing by these techniques. This new solvent treatment approach improves on others reported in the literature which either use carcinogenic solvents or yield solvent-soaked powders that are difficult to process in the 1–5 kg range suitable for bench-top units. In an initial scoping study, we identify acetophenone as a suitable non-hazardous solvent for this process which we then scale to the ∼kilogram scale. Finally, we demonstrate processability of this feedstock by PBF-LB/P using a bed temperature (Tbed) well above the Tg of this feedstock.
{"title":"Enabling powder bed fusion (PBF) processing of polyether imide (PEI) through mixed-phase solvent processing","authors":"C. Garrett Campbell , Camden Chatham , Samantha J. (Lindholm) Knight , E. Cade Willis , Andrew P. Rhodes","doi":"10.1016/j.addlet.2026.100369","DOIUrl":"10.1016/j.addlet.2026.100369","url":null,"abstract":"<div><div>Polymeric material options for powder bed fusion (PBF) additive manufacturing (AM) techniques are typically limited to semicrystalline thermoplastics with large differences between their melting and recrystallization temperatures. Amorphous thermoplastics like polyetherimides (PEIs) are desired in certain applications but cannot be effectively processed by PBF due to their lack of crystallinity. Herein, we present a new solvent processing method which induces crystallinity in a particular grade of PEI, Ultem CRS5011, thus enabling its processing by these techniques. This new solvent treatment approach improves on others reported in the literature which either use carcinogenic solvents or yield solvent-soaked powders that are difficult to process in the 1–5 kg range suitable for bench-top units. In an initial scoping study, we identify acetophenone as a suitable non-hazardous solvent for this process which we then scale to the ∼kilogram scale. Finally, we demonstrate processability of this feedstock by PBF-LB/P using a bed temperature (T<sub>bed</sub>) well above the T<sub>g</sub> of this feedstock.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"17 ","pages":"Article 100369"},"PeriodicalIF":4.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-07DOI: 10.1016/j.addlet.2026.100356
Guoyuan Qiu , Yaning Tang , Jianjun Lin , Jeremy Heng Rao , Xing Gong , Changyong Liu , Zhangwei Chen , Chao Dong , Zhiyuan Liu
Emerging 4D printing is an innovative additive manufacturing (AM) technique that incorporates an extra dimension of time into AM. 4D printed objects can change their shapes or properties in response to external stimuli. However, the intrinsic microstructural anisotropy also affects the shape memory performance of AM printed shape memory alloys (SMAs). This work investigated the effect of TiN nanoparticle addition on the mechanical and shape-memory properties of a high entropy shape memory alloy (HESMA) Fe50Mn20Co10Cr10Si10 (at.%) fabricated by laser powder bed fusion (LPBF). Results show that the TiN addition enhances the yield strength (YS) of the AM HESMA at the expense of ductility. Meanwhile, the as-built shape memory performance is reduced, with the maximum bending recovery strain of the vertical sample decreasing from 6.3 % to 4.7 %. Moreover, it is shown that introducing TiN nanoparticles can significantly alleviate the 4D-printing anisotropy. The YS anisotropy ratio is reduced from 40.0 % to 20.5 %, and the shape memory anisotropy ratio decreases from 56.3 % to 14.9 %. The underlying reason is attributed to a columnar-to-equiaxed microstructure transition induced by the TiN addition, which results in similar amount of grain boundaries during deformation in different directions. To restore the shape memory ability, the TiN/HESMA is subjected to further heat treatment. The maximum recovery strain is improved greatly and approaching that of HESMA matrix, and the shape memory anisotropy ratio further decreases to 3.4 %. The underlying mechanism of the heat treatment is revealed. The synergy of TiN addition and heat treatment provides a novel approach to balance strength enhancement and functional anisotropy of 4D printing
{"title":"Effect of TiN nanoparticle on shape memory properties of additively manufactured ferrous high entropy shape memory alloy","authors":"Guoyuan Qiu , Yaning Tang , Jianjun Lin , Jeremy Heng Rao , Xing Gong , Changyong Liu , Zhangwei Chen , Chao Dong , Zhiyuan Liu","doi":"10.1016/j.addlet.2026.100356","DOIUrl":"10.1016/j.addlet.2026.100356","url":null,"abstract":"<div><div>Emerging 4D printing is an innovative additive manufacturing (AM) technique that incorporates an extra dimension of time into AM. 4D printed objects can change their shapes or properties in response to external stimuli. However, the intrinsic microstructural anisotropy also affects the shape memory performance of AM printed shape memory alloys (SMAs). This work investigated the effect of TiN nanoparticle addition on the mechanical and shape-memory properties of a high entropy shape memory alloy (HESMA) Fe<sub>50</sub>Mn<sub>20</sub>Co<sub>10</sub>Cr<sub>10</sub>Si<sub>10</sub> (at.%) fabricated by laser powder bed fusion (LPBF). Results show that the TiN addition enhances the yield strength (YS) of the AM HESMA at the expense of ductility. Meanwhile, the as-built shape memory performance is reduced, with the maximum bending recovery strain of the vertical sample decreasing from 6.3 % to 4.7 %. Moreover, it is shown that introducing TiN nanoparticles can significantly alleviate the 4D-printing anisotropy. The YS anisotropy ratio is reduced from 40.0 % to 20.5 %, and the shape memory anisotropy ratio decreases from 56.3 % to 14.9 %. The underlying reason is attributed to a columnar-to-equiaxed microstructure transition induced by the TiN addition, which results in similar amount of grain boundaries during deformation in different directions. To restore the shape memory ability, the TiN/HESMA is subjected to further heat treatment. The maximum recovery strain is improved greatly and approaching that of HESMA matrix, and the shape memory anisotropy ratio further decreases to 3.4 %. The underlying mechanism of the heat treatment is revealed. The synergy of TiN addition and heat treatment provides a novel approach to balance strength enhancement and functional anisotropy of 4D printing</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"17 ","pages":"Article 100356"},"PeriodicalIF":4.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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