17 21 29 P. 11 View into a Metallurgical Lab Focused on AM Powder Sustainable Process Reclaims Metals for AM Applications SMST NewsWire Included in This Issue EXAMINING NICKEL SUPERALLOYS PROCESSED BY LASER POWDER BED FUSION ADDITIVE MANUFACTURING MARCH 2025 | VOL 183 | NO 2
17 21 29 P. 11 View into a Metallurgical Lab Focused on AM Powder Sustainable Process Reclaims Metals for AM Applications SMST NewsWire Included in This Issue EXAMINING NICKEL SUPERALLOYS PROCESSED BY LASER POWDER BED FUSION ADDITIVE MANUFACTURING MARCH 2025 | VOL 183 | NO 2
INTERNATIONAL CONFERENCE ON ADVANCES IN MATERIALS, MANUFACTURING & REPAIR FOR POWER PLANTS (EPRI) FEBRUARY 25 – 28, 2025 | INDIAN WELLS (PALM SPRINGS), CALIFORNIA As the world undergoes an energy transformation, the safe, reliable, affordable, and environmentally responsible operation of today’s and tomorrow’s power plants requires continued advancement in high-temperature materials technology. Materials serve as the key enabling technology driving the development of high-efficiency power conversion technologies. INTERNATIONAL THERMAL SPRAY CONFERENCE & EXPOSITION (ITSC) MAY 5 – 8, 2025 | VANCOUVER, CANADA ITSC is the world’s foremost international conference and exhibition for thermal spray technologists, researchers, manufacturers, and suppliers. This conference rotates between North America, Europe, and the Pacific Rim and is organized by the ASM Thermal Spray Society, the German Welding Society (DVS), and International Institute of Welding (iiw). 3RD INTERNATIONAL CONFERENCE ON QUENCHING & DISTORTION ENGINEERING (QDE) MAY 6 – 7, 2025 | VANCOUVER, CANADA This event is the global gathering for professionals and researchers in the field of quenching and distortion engineering. Join us for an immersive experience filled with cutting-edge research presentations, insightful discussions, and unparalleled networking opportunities. AEROMAT MAY 6 – 8, 2025 | VANCOUVER, CANADA AeroMat focuses on innovative aerospace materials, fabrication, and manufacturing methods that improve performance, durability, and sustainability of aerospace structures and engines with reduced life-cycle costs. 2ND SHAPE MEMORY & SUPERELASTIC TECHNOLOGIES (SMST) IRELAND MAY 22, 2025 | GALWAY, IRELAND The 2nd SMST Ireland event will be a pivotal gathering in the MedTech industry, spotlighting the dynamic role of Nitinol in design and manufacturing. With the theme “Engaging and Enabling Irish MedTech for Design and Manufacturing with Nitinol,” the conference aims to explore the transformative potential of this unique alloy in advancing medical technology. INTERNATIONAL CONFERENCE ON RESIDUAL STRESSES (ICRS) OCTOBER 20 – 23, 2025 | DETROIT, MICHIGAN Discover the forefront of residual stress research and its impact on material behavior at this enriching event. Engage with experts and practitioners across diverse fields through our symposium topics, networking opportunities, and technical programming. INTERNATIONAL MATERIALS, APPLICATIONS & TECHNOLOGIES (IMAT) OCTOBER 20 – 23, 2025 | DETROIT, MICHIGAN IMAT, ASM’s annual event, is the only targeted conference on advanced materials, applications, and technologies in key growth markets that will have a focus on economic trends and business forecasts. The event will include a diverse group of materials experts, including the ASM Programming Committees and all six of ASM’s Affiliate Societies, who are heavily involved in building the technical symposiums, which will have a strong focus on realworld technologies that can be put to use today. HEAT TREAT 2025 OCTOBER 21 – 23, 2025 | DETROIT, MICHIGAN Discover the unrivaled opportunities awaiting you at Heat Treat Conference/Expo! As the LARGEST gathering for heat treating professionals, materials experts, and industry leaders in North America, Heat Treat is a MUST-ATTEND event! INTERNATIONAL SYMPOSIUM FOR TESTING AND FAILURE ANALYSIS (ISTFA) NOVEMBER 16 – 20, 2025 | PASADENA, CALIFORNIA ISTFA is the only North American event devoted to the semiconductor, electronic sample preparation, and imaging markets. ISTFA offers the best venue for failure analysts and the FA community for sharing challenges and acquiring the technical knowledge and resources needed to take them on. Showcase your thought leadership and innovations at one of ASMʼs 2025 conferences and expositions, which offer unparalleled access to highly engaged audiences of industry leaders and decision-makers. Learn more about each event and related exhibit and sponsorship opportunities at asminternational.org/events
3 EVENTS • 1 LOCATION SUSTAINABLE INNOVATIONS IN THERMAL SPRAY TECHNOLOGY: PIONEERING A GREENER FUTURE INNOVATIONS IN MATERIALS ENGINEERING: SHAPING THE FUTURE OF THE AEROSPACE INDUSTRY 2025 MAY 5–8, 2025 VANCOUVER CONVENTION CENTER | VANCOUVER, CANADA REGISTRATION NOW OPEN! REGISTER BY APRIL 1 FOR THE EARLY BIRD DISCOUNT ITSCevent.org QDEevent.org AeroMatevent.org CO-LOCATED WITH: OFFICIAL MEDIA SPONSOR: 3RD INTERNATIONAL CONFERENCE ON QUENCHING AND DISTORTION ENGINEERING ORGANIZED BY:
45 ASM NEWS The latest news about ASM members, chapters, events, awards, conferences, affiliates, and other Society activities. RELATING PROCESS ANOMALIES FROM LASER POWDER BED FUSION OF Ni282 TO CREEP DEFORMATION Holden Hyer, Amanda Heimbrook, Rahul Franklin, Amir Ziabari, and Sebastien Dryepondt This examination of the spatter particle process in a nickel superalloy using x-ray computed tomography and optical microscopy studies possible causes for the formation of lack of fusion voids and other variations during laser powder bed fusion. 11 ADVANCED MATERIALS & PROCESSES | MARCH 2025 2 Additive manufacturing includes advanced methods such as laser powder bed fusion. Image AI enhanced. Courtesy of Dreamstime. On the Cover: 60 3D PRINTSHOP A look at a coin-sized photonic chip 3D printer and a cement material with high structural viability. METALS/POLYMERS/ CERAMICS Researchers are investigating cordierite’s properties, editing plastic waste to generate new polymers with improved attributes, and creating smart fabric that heats up when exposed to the sun. 6
4 Editorial 5 Research Tracks 6 Metals/Polymers/Ceramics 8 Testing/Characterization 10 Process Technology 59 Editorial Preview 59 Special Advertising Section 59 Advertisers Index 60 3D PrintShop TRENDS INDUSTRY NEWS DEPARTMENTS Check out the Digital Edition online at asminternational.org/news/magazines/am-p ASM International serves materials professionals, nontechnical personnel, and managers worldwide by providing high-quality materials information, education and training, networking opportunities, and professional development resources in cost-e ective and user-friendly formats. ASM is where materials users, producers, and manufacturers converge to do business. Advanced Materials & Processes (ISSN 0882-7958, USPS 762080) publishes eight issues per year: January/February, March, April, May/June, July/August, September, October, and November/December, by ASM International, 9639 Kinsman Road, Materials Park, OH 44073-0002; tel: 440.338.5151; fax: 440.338.4634. Periodicals postage paid at Novelty, Ohio, and additional mailing offices. Vol. 183, No. 2, MARCH 2025. Copyright © 2025 by ASM International®. All rights reserved. Distributed at no charge to ASM members in the United States, Canada, and Mexico. International members can pay a $30 per year surcharge to receive printed issues. Subscriptions: $499. Single copies: $54. POSTMASTER: Send 3579 forms to ASM International, Materials Park, OH 44073-0002. Change of address: Request for change should include old address of the subscriber. Missing numbers due to “change of address” cannot be replaced. Claims for nondelivery must be made within 60 days of issue. Canada Post Publications Mail Agreement No. 40732105. Return undeliverable Canadian addresses to: 13487 S Preston Hwy, Lebanon Junction, KY 40150. Printed by Kodi Collective, Lebanon Junction, Ky. 17 BEST PRACTICES FOR METALLOGRAPHY IN A POWDER TESTING LABORATORY Dana M. Drake This article highlights some of the best metallographic practices from a laser powder bed fusion laboratory and provides practical observations of the more universal aspects of powder testing. 21 REACHING FOR ‘GREEN’ WITH RECLAIMED METALS Sunil Badwe Sustainable, advanced-plasma technology atomizes scrap alloys into ‘in spec’ powder for additive manufacturing and other industrial applications. 25 EXPLORING THE USE OF BRAID IN ADVANCED COMPOSITE STRUCTURES Alexandra Ivers, Molly Dingeldein, Stephanie Kramig, and Nathan Jessie Braid allows for the creation of composite parts with an efficient fiber architecture and provides manufacturers with a material that results in fewer processing steps and less waste than woven alternatives. FEATURES MARCH 2025 | VOL 183 | NO 2 ADVANCED MATERIALS & PROCESSES | MARCH 2025 3 17 25 29 21 29 SMST NEWSWIRE The official newsletter of the International Organization on Shape Memory and Superelastic Technologies (SMST). This biannual supplement covers shape memory and superelastic technologies for biomedical, actuator applications, and emerging markets, along with SMST news and initiatives.
4 ADVANCED MATERIALS & PROCESSES | MARCH 2025 ASM International 9639 Kinsman Road, Materials Park, OH 44073 Tel: 440.338.5151 • Fax: 440.338.4634 Joanne Miller, Editor joanne.miller@asminternational.org Victoria Burt, Managing Editor vicki.burt@asminternational.org Frances Richards and Corinne Richards Contributing Editors Anne Vidmar, Layout and Design Allison Freeman, Production Manager allie.freeman@asminternational.org EDITORIAL COMMITTEE John Shingledecker, Chair, EPRI Beth Armstrong, Vice Chair, Oak Ridge National Lab Adam Farrow, Past Chair, Los Alamos National Lab Yun Bai, Ford Rajan Bhambroo, Tenneco Inc. Punnathat Bordeenithikasem, Machina Labs Daniel Grice, Materials Evaluation & Engineering Surojit Gupta, University of North Dakota Michael Hoerner, KnightHawk Engineering Hideyuki Kanematsu, Suzuka National College of Technology Ibrahim Karaman, Texas A&M University Ricardo Komai, Tesla Krassimir Marchev, Northeastern University Bhargavi Mummareddy, Dimensional Energy Scott Olig, U.S. Naval Research Lab Christian Paglia, SUPSI Institute of Materials and Construction Satyam Sahay, John Deere Technology Center India Abhijit Sengupta, USA Federal Government Kumar Sridharan, University of Wisconsin Vasisht Venkatesh, Pratt & Whitney ASM BOARD OF TRUSTEES Navin Manjooran, President and Chair Elizabeth Ho man, Senior Vice President Daniel P. Dennies, Vice President Pradeep Goyal, Immediate Past President Lawrence Somrack, Treasurer Amber Black Pierpaolo Carlone Rahul Gupta Hanchen Huang André McDonald Victoria Miller Christopher J. Misorski Dehua Yang Fan Zhang Veronica Becker, Executive Director STUDENT BOARD MEMBERS Gladys Duran Duran, Amanda Smith, Nathaniel Tomas Individual readers of Advanced Materials & Processes may, without charge, make single copies of pages therefrom for personal or archival use, or may freely make such copies in such numbers as are deemed useful for educational or research purposes and are not for sale or resale. Permission is granted to cite or quote from articles herein, provided customary acknowledgment of the authors and source is made. The acceptance and publication of manuscripts in Advanced Materials & Processes does not imply that the reviewers, editors, or publisher accept, approve, or endorse the data, opinions, and conclusions of the authors. AM BRINGS ON INNOVATIONS Amazing innovations are occurring every day in the world of materials. Additive manufacturing (AM) processes can be found at the core of many of those advances. Among its benefits over traditional manufacturing methods are design flexibility, rapid prototyping, increased customization, fewer defects, lower cost, and reduced waste. And let’s not forget the wow factor. Recently, a team at the University of Glasgow created the world’s first 3D-printed microscope in under three hours. The microscope has a single lens with a 2.9× magnification and was made for less than 50 dollars. For more clever applications of AM, turn to our 3D PrintShop page and learn about a miniature 3D printer that can fit into the palm of your hand. In another story, you can read about how 3D-printed bendable concrete could revolutionize the construction industry. Other impressive applications are being employed to solve problems in space. NASA is conducting experiments on the International Space Station to examine the behavior of colloids or “soft matter” in the microgravity environment. Knowledge gathered from those studies will help astronauts build or repair equipment and materials in space, exactly when the need arises. Bringing the conversation back to earth for some practical uses here, this issue of AM&P offers several articles with scientific results and pragmatic tips from various AM practitioners. Holden Hyer from Oak Ridge National Laboratory (ORNL) provides insights into the use of laser powder bed fusion for rapid qualification of new materials in the nuclear sector. By pairing two microstructural characterization methods, the quality and long-term performance of nickel-base AM components in their study can be accurately evaluated. For more from ORNL, turn to our Research Tracks page to learn about a partnership with the DOE’s Idaho National Laboratory that is improving the inspection process of additively manufactured nuclear components. Their next challenge is to use their specialized technology to conduct quality checks on nuclear fuel cells. Next, we move from the national labs to a commercial lab. With Dana Drake as our tour guide, we get a glimpse into the workings of an AM-focused metallurgical lab at EOS in Texas. Her article describes best practices the team follows in conducting metallographic inspections of AM powders. And finally, checking in with industry, the R&D folks at Continuum Powders share an article that addresses how powder operations could be made “green” through a single-step plasma-assisted atomization process. Their method allows for more scrap alloy to be collected and repurposed for future AM projects. Whether a specific AM application is backed by strong scientific data with practical uses or just has the wow factor, AM is here to stay. And we can count on it to bring on more innovations. joanne.miller@asminternational.org 3D-printed microscope. Courtesy of University of Strathclyde, Glasgow.
ADVANCED MATERIALS & PROCESSES | MARCH 2025 5 RESEARCH TRACKS SOUPED-UP SUPERGLUE BIODEGRADES Researchers at Colorado State University (CSU) and their colleagues at the National Renewable Energy Laboratory and University of California, Berkeley developed an adhesive polymer that is stronger than those commercially available—in addition to being biodegradable and reusable. Poly(3-hydroxybutyrate), known as P3HB, is a natural, bio-based, and biodegradable polymer that can be produced by microbes under the right biological conditions. While the polymer is not adhesive when made that way, the team was able to chemically reengineer its structure to deliver stronger adhesion than the common petroleum-derived, nonbiodegradable options when used on substrates or surfaces such as aluminum, glass, and wood. The adhesion strength of the reengineered P3HB can also be tuned to accommodate different application needs. “Petroleum-based thermoset adhesives such as Gorilla Glue and J-B Weld, along with thermoplastic hot melts, can be very difficult or even impossible to recycle or recover—primarily because of their strong bonds to other materials,” says CSU professor and lead researcher Eugene Chen. “Our approach instead offers a biodegradable material that can be used in a variety of industries with tunable or even higher strength compared to those options.” His team at CSU team is now working on ways to commercialize the polymer for broad use. colostate.edu. COLLABORATION VETS NUCLEAR COMPONENTS A research partnership between the DOE’s Idaho National Laboratory (INL) and Oak Ridge National Laboratory (ORNL) has accelerated inspection of additively manufactured (AM) nuclear INL researchers use ORNL software to reduce the x-ray CT scan time and improve image accuracy for 3D-printed parts. Courtesy of Bill Chuirazzi/INL. components, and the effort is now expanding to inspect nuclear fuels. INL is using a software algorithm developed by ORNL to check for flaws in AM components as part of the process of identifying promising metals and alloys for 3D printing the next generation of nuclear reactors. The ORNL-developed technology has been so successful that researchers are now training the algorithm to inspect the ceramic casings of irradiated nuclear fuel tested at INL. “If we use this algorithm to reduce the scan time for radioactive fuels by 90%, it will increase worker safety and the rate we can evaluate new materials,” says Bill Chuirazzi, an instrument scientist at INL. The ramifications for the nuclear field extend far beyond the current project. “Down the road, it enables us to expedite the life cycle of new nuclear ideas from conception to implementation in the power grid.” The availability of advanced computational and characterization capabilities across both laboratories will accelerate the qualification of materials for 3D-printed nuclear components and the develop- ment of new fuel designs, helping the industry deploy new reactors more efficiently. inl.gov, ornl.gov. Biodegradable sr-P3HB adhesive applied between two steel plates suffers no failure, even with 20 lb load. Savannah River National Laboratory, Aiken, S.C., will receive $6 million to lead two projects related to fusion materials: “Non-Aqueous 2-D Material Based Hydrogen Isotope Separation” and “Development and De-risking of Li Electrolysis and CoRExt Process by Flow-Loop Integration.” Both focus on challenges in fuel cycle and blanket technologies, and tritium interactions with materials. srnl.gov. BRIEF
ADVANCED MATERIALS & PROCESSES | MARCH 2025 6 METALS | POLYMERS | CERAMICS Stardust Power Inc., Greenwich, Conn., broke ground in January on its lithium refinery in Muskogee, Okla. The project’s first phase will build a production line to make 25,000 metric tons of battery-grade lithium per year. The second phase will add another line, doubling capacity. stardustpower.com POLYMER EDITING FOR PLASTICS Chemists at the DOE’s Oak Ridge National Laboratory, Tenn., have found a way to edit the polymers of discarded plastics and generate new macromolecules with more valuable properties than those of the starting material. The discovery could lead to the ability to rearrange polymeric building blocks to customize the properties of plastics. In some experiments, the team worked with polybutadiene, common in rubber tires. In other cases, they worked with acrylonitrile butadiene styrene, often used for things like toys, keyboards, and appliances. Researchers shredded synthetic or commercial polybutadiene and acrylonitrile butadiene styrene and immersed the material in dichloromethane to conduct a chemical reaction at 40°C for less than two hours. CORDIERITE’S THERMAL EXPANSION EXPLAINED Researchers at Queen Mary University of London report discovering the fundamental reasons behind cordierite’s ability to resist changes in size despite significant temperature fluctuations. They say their findings could have profound implications for the design and development of advanced materials. While widely used in applications from pizza stones and catalytic converters to high-temperature industrial processes, the mineral’s unusual thermal behavior has not been well understood until now. Unlike most materials, cordierite displays an unusual combination of thermal expansions—low positive expansion along two perpendicular axes and negative expansion along the third. This unique behavior has made cordierite especially useful in applications requiring exceptional thermal stability. In their study, the team used advanced lattice dynamics and molecular dynamics simulations, employing transferable force fields to model the atomic structure of cordierite under varying thermal conditions. The simulations accurately reproduced experimental data, providing insights into the mineral’s behavior at both low and high temperatures. At lower temperatures, the scientists observed that lower-frequency vibrations favor negative thermal expansion along all three axes. At higher temperatures, higher-frequency vibrations dominate, leading to positive expansion. Further, these actions are counterbalanced by the material’s elastic properties, which act like a 3D hinge to effectively cancel out many of the thermal effects. These findings could lead to the design of materials with tailored thermal properties, say researchers. The method of combining simulations of atomic vibrations with elasticity models could be directly applied to other anisotropic materials. www.qmul.ac.uk. Standard Lithium Ltd., Lewisville, Ark., and Equinor, Houston, announced Smackover Lithium as the new name for their joint venture developing direct lithium extraction projects in Southwest Arkansas and East Texas. smackoverlithium.com. BRIEFS Crystal structure of cordierite. Courtesy of M. Dove et al./Matter. To upcycle the polymers of plastic waste, chemists generated new macromolecules with more valuable properties than the original material. Courtesy of Adam Malin/ORNL, U.S. Dept. of Energy.
ADVANCED MATERIALS & PROCESSES | MARCH 2025 7 The molecular building blocks of the polymer backbone contain functional groups that serve as reactive sites for modification. Notably, the double bonds between carbons increase the chances for chemical reactions that enable polymerization. A carbon ring opens at a double bond to create a polymer chain that grows as each functional polymer unit directly slips in, conserving the material. The plastic additive also helps control the molecular weight of the synthesized material as well as its properties and performance. If scaled up and expanded to employ other additives, broader classes of waste could be mined for molecular building blocks, dramatically reducing the environmental impact of other difficult-to-process plastics. ornl.gov. SMART FABRIC FOR WINTER WARMTH Researchers at the University of Waterloo, Canada, developed a new type of cloth that heats up when exposed to the sun due to specialized nanoparticles embedded in the fabric’s fiber. Traditional forms of heated clothing usually rely on metal or ceramic elements to warm up in addition to an external power source. The new cloth incorporates conductive polymer nanoparticles that can reach 30°C under sunlight. The design does not require external power and can also change color to visually monitor temperature fluctuations. The fiber is created by a scalable wet-spinning process, combining polyaniline and poly- dopamine nanoparticles to enhance light absorption and improve photo- thermal conversion. Thermoplastic poly- urethane serves as the spinning matrix, while thermochromic dyes enable the reversible color-changing feature. The resultant fiber can be woven into fabric for wearable applications. In addition to its temperature- changing capability, the new fabric can stretch out by as much as five times its original shape and withstand as much as 24 washings while still maintaining its function and appearance. Its reversible color-changing ability also provides a built-in temperature monitoring feature to ensure the wearer’s safety and convenience. Potential applications include aiding in cold rescue situations and keeping animals warm with solar-powered pet clothing. www.uwaterloo.ca. This smart fabric can change its color when nanoparticles embedded in the fibers are activated by sunlight. Courtesy of the University of Waterloo. TECHNICAL SUPPORT EPOXIES, SILICONES & UV/LED CURING CUSTOM FORMULATIONS Select the right adhesive www.masterbond.com 154 Hobart Street, Hackensack, NJ 07601 USA• +1.201.343.898 • mainmasterbond.com
8 ADVANCED MATERIALS & PROCESSES | MARCH 2025 strontium titanate (STO) substrate. The scientists found that FeSe has a transition-to-superconductivity temperature of 65 K, approximately -340°F, making it the highest-temperature super- conductor in its class. They witnessed a close relationship between electron- phonon coupling and the uniformity of the FeSe/STO interface. This greater homogeneity means a higher temperature at which superconductivity occurs. “Our vibrational spectroscopy approach enabled us to achieve highly detailed imaging of the vibrations at the superconducting material’s interface with its substrate,” says researcher and materials science professor Xiaoqing Pan. “The observed variation in the interlayer spacing correlates with the superconducting gap, which demonstrates the crucial role of spacing in electron-phonon coupling strength and superconductivity.” Pan added that his TESTING | CHARACTERIZATION HEXAGONAL BORON NITRIDE BREAKTHROUGH Researchers at the University of Surrey, U.K., report a new development in decoding the growth process of hexagonal boron nitride (hBN), a 2D material, and its nanostructures on metal substrates. They say this discovery could lead to more efficient electronics, cleaner energy solutions, and more environmentally benign chemical manufacturing. Often called “white graphene,” one-atom-thick hBN is an extremely thin and resilient material that blocks electrical currents, withstands extreme temperatures, and resists chemical damage. The research team also demonstrated the formation of nanoporous hBN, a unique material with structured voids that allows for selective absorption and advanced catalysis, greatly expanding potential environmental applications. Examples include sensing and filtering pollutants as well as enhancing advanced energy systems such as hydrogen storage and electrochemical catalysts for fuel cells. Working in collaboration with Graz University of Technology, Austria, researchers combined density functional theory and micro- kinetic modeling to map the growth process of hBN from borazine precursors. They examined key molecular processes such as diffusion, decomposition, adsorption and desorption, polymerization, and dehydrogenation. This approach helped them develop an atomic scale model that enables the material to be grown at any temperature. www.surrey.ac.uk. SPECTROSCOPY EXPLORES SUPERCONDUCTIVITY Researchers at the University of California (UC), Irvine, say they have uncovered the atomic- scale mechanics that enhance superconductivity in an iron- based material. Using advanced spectroscopy instruments at the UC Irvine Materials Research Institute (IMRI), the team was able to image atom vibrations and thereby observe new phonons at the interface of an iron selenide (FeSe) ultrathin film layered on a Xiaoqing Pan displays IMRI equipment that allowed his team to image atom vibrations at the interface between a superconductor and a substrate. Courtesy of Steve Zylius/UC Irvine. Model of “white graphene” maps the growth process of hBN. Courtesy of University of Surrey. LK Metrology Ltd., U.K., acquired Nikon Corp.’s laser scanning and Focus Inspection point cloud software business. The deal includes all of Nikon Metrology’s laser scanning R&D, service, and production resources. lkmetrology.com. Exact Metrology, Milwaukee, is partnering with Hexagon Manufacturing Intelligence, Sweden. Hexagon manufactures digital reality products that integrate sensors, software, and autonomous technologies. Industries served include aerospace, automotive, defense, medical, industrial manufacturing, and clean energy. exactmetrology.com. BRIEFS
ADVANCED MATERIALS & PROCESSES | MARCH 2025 9 team’s results are an important step toward achieving scalable fabrication and utilization of superconductors in a wide range of applications. Examples include quantum computers, mass transit using magnetic levitation, and advanced medical diagnostic and treatment devices. uci.edu. QUASIPARTICLE DISCOVERY IMPACTS MAGNETISM Two scientists at the University of Missouri, Columbia, along with their teams of students and postdoctoral fellows, recently made a significant discovery on the nanoscale. They found a new type of quasiparticle that exists in all magnetic materials, regardless of strength or temperature. These new properties challenge what researchers previously assumed about magnetism, showing that it is not as static as once believed. “We’ve all seen the bubbles that form in sparkling water or other carbonated drink products,” says researcher Carsten Ullrich. “The quasiparticles are like those bubbles, and we found they can freely move around at remarkably fast speeds.” The team believes this discovery could help support development of a new generation of electronics that are faster, smarter, and more energy efficient. However, the scientists first need to determine how this finding could work into those processes. One field that could directly benefit from the new discovery is spintronics. While traditional electronics use the electrical charge of electrons to store and process information, spintronics uses the natural spin of electrons—a property intrinsically linked to the quantum nature of electrons. For example, a cell phone battery could last for hundreds of hours on one charge when powered by spintronics. “The spin nature of these electrons is responsible for the magnetic phenomena,” explains researcher Deepak Singh. “Electrons have two properties: a charge and a spin. So, instead Deepak Singh (right) works on spintronics with a graduate student in Singh’s lab. Courtesy of University of Missouri. of using the conventional charge, we use the rotational, or spinning, property. It’s more efficient because the spin dissipates much less energy than the charge.” Singh’s group conducted the experiments while Ullrich’s team analyzed Singh’s results and created models to explain the unique behavior they were observing under powerful spectrometers at Oak Ridge National Laboratory. missouri.edu. Ovens and Furnaces for Laboratories & Materials Testing Systems Thermcraft LAB-TEMP™ exclusively supplies laboratory furnaces and ovens to many leading materials testing system manufacturers around the world. • Stainless steel constructed exteriors • Designed to work with all types of material testing systems • Manufactured for new OEM systems or retrofitted • Designed for horizontal or vertical operation • Available with various types of mounting brackets or stands • Optional ports for atmosphere introduction
ADVANCED MATERIALS & PROCESSES | MARCH 2025 10 PROCESS TECHNOLOGY FASTER WELDING FOR FUEL CELLS Researchers at Penn State combined observation and analytical modeling to identify the conditions that produce humping at high laser welding speeds and to adjust the process to increase speed without causing surface irregularities. “We wanted to increase the laser welding speed to increase the production rate for fuel cell bipolar plates, which are an important component in fuel cells,” says researcher the largest simulation ever on this type of polymer and confirmed theoretical predictions, finding that the ring polymers spontaneously solidify into a glass when their chains become sufficiently long. The study shows how changing the shape of polymers from open strings to closed rings drastically alters how the molecules pack and diffuse inside the material. Researchers found that as ring polymers become onger, separate chains become increasingly cramped together until the chains cannot move, causing the material to solidify. The simple act of changing the shape of the molecules from open strings to closed rings also changed the plastics phase from a liquid to a solid. The scientists ran large-scale molecular dynamics simulations for more than a year on DOE supercomputers to test the theoretical predictions developed by their colleagues at UIUC. The simulations built on previous research from the team where they experimentally synthesized a recyclable polymer material made of pure ring polymers that unexpectedly vitrified in the lab. These new theoretical results explain this surprising behavior and could help drive the design of recyclable cyclic polymers. cmu.edu. Jingjing Li. Bipolar plates are formed by welding two panels together and the channels that form in these plates are necessary for energy generation in fuel cells. The production rate of bipolar plates was previously limited because welding speeds were restricted to prevent humping. Using high-speed synchrotron x-ray imaging, the team observed the process in real time at extreme detail. They then designed a numerical simulation to correlate with the experimental observation and developed an equation to link defects with process parameters. By adjusting welding conditions, researchers modeled various process parameters to create a hump-free weld even at high speeds. When welding speed becomes too high, the materials being welded develop large molten metal pools that contribute to the hump. Researchers realized that the molten pools needed to be stabilized, which they could do by applying a shielding gas or adjusting the shape of the welding laser beam. These simple adjustments increased the production rate to 75 meters of steel per minute—from the previous rate of just 20—and without humps. psu.edu. RING-SHAPED POLYMERS GEL INTO GLASS Researchers from Carnegie Mellon, Sandia National Laboratories, and the University of Illinois Urbana-Champaign (UIUC) made a new discovery regarding ring-shaped polymers that they say has potential to help create more sustainable materials. The scientists conducted Norman Noble Inc. is expanding its micromachining facility in Naples, Fla., adding advanced milling and Swiss machines and automated deburring technologies. The new equipment will ensure precision and quality while streamlining the manufacture of orthopedic medical implants such as Nitinol staples, spine implants, orthopedic plates, screws, and anchors as well as vascular implants. nnoble.com. BRIEF Penn State researchers are able to model various process parameters to create a hump-free weld of bipolar plates even at high speeds. Courtesy of Zen-Hao Lai and Jingjing Li. Example of molecular modeling and simulation used by researchers to design sustainable polymers. Courtesy of Carnegie Mellon University.
ADVANCED MATERIALS & PROCESSES | MARCH 2025 1 1 ADDITIVE MANUFACTURING MARCH 2025 A 3D-printed oak leaf fabricated from alumina forming austenitic stainless steel using a Renishaw AM400 laser powder bed fusion system, by Holden Hyer at Oak Ridge National Laboratory. *Member of ASM International This examination of the spatter particle process in a nickel superalloy using x-ray computed tomography and optical microscopy studies possible causes for the formation of lack of fusion voids and other variations during laser powder bed fusion. RELATING PROCESS ANOMALIES FROM LASER POWDER BED FUSION OF Ni282 TO CREEP DEFORMATION Holden Hyer,* Amanda Heimbrook, Rahul Franklin, Amir Ziabari, and Sebastien Dryepondt* Oak Ridge National Laboratory, Tennessee
ADVANCED MATERIALS & PROCESSES | MARCH 2025 12 Nuclear reactor designs have only seen incremental technological advancements since the 1950s. Materials systems used to build reactors still include Zr-alloys as fuel cladding, stainless steels for structural components, and some use of Ni-based super- alloys in the coolant pumps and turbines, despite the large body of development in metal alloys[1]. The challenge lies with materials qualification, a rigorous process requiring exhaustive mechanical testing, and in some cases, irradiation data needed for confidence in the material’s performance. For example, the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) requires extensive materials testing that could take more than 10 years to satisfy all the requirements needed[2]. Section III, Division 5 of the ASME BPVC currently only lists six alloys that have met all the requirements for qualification: SS304, SS316, Fe-2.25Cr-1Mo, Fe-9Cr-1Mo, Alloy 800H, and the most recent addition, IN617, which was added in 2020[2,3]. BACKGROUND AND MOTIVATION Safety-oriented industries such as nuclear have adopted a design–manufacture–test approach to qualification that provides continuous feedback. Additive manufacturing (AM) techniques have realized the ability to fabricate custom designed components to nearnet shape from a wide variety of materials[4]. AM enables reactor designers to optimize complex geometries, not thought possible with conventional manufacturing techniques; moreover, the fast turnaround of the AM process allows for rapid prototyping of the design before moving on to the test stage. The U.S. Department of Energy (DOE) Office of Nuclear Energy established the Advanced Materials and Manufacturing Technologies (AMMT) program to build a rapid qualification framework that takes a more manufacturing and microstructure approach to evaluating new materials and their performance and eventual deployment in nuclear reactors[5-7]. The AMMT program has identified multiple AM and other advanced techniques, but has taken special interest in laser powder bed fusion (LPBF) AM due to the high geometric resolution (<100 µm) that can be achieved across a variety of materials. A schematic of the LPBF process is shown in Fig. 1. During the LPBF process, powder is dispensed into the system and wiped over a starting substrate (i.e., build plate), before the laser selectively melts the profile of the desired component to the base; powder layers are typically <100 µm, requiring hundreds to thousands of consecutive layers to build components[4]. The repetitive local melting of the laser is conducive to high cooling rates, on the orders of 105–107 K/s[8], which can greatly vary the microstructure and generate high residual strains. Moreover, the complex melting and solidification can result in the formation of many process anomalies such as pores, cracks, and layer delamination. In-situ monitoring capabilities integrated with software such as Peregrine, developed at Oak Ridge National Laboratory, is trained to observe process anomalies related to the printing process such as part over-melting or recoater streaking and digging that may cause incomplete melting[9-11]. One process anomaly that can be detected with in-situ capabilities is the formation of spatter particles due to the recoil pressure associated with the laser interacting with the powder bed, which is quite violent, sending particles hurdling upward in the chamber[12], as shown in Fig. 1. An inert gas shroud is often used to sweep over the top of the powder bed and carry spattered particles across to the side, since these particles can oxidize with any remaining oxygen in the build chamber, or coalesce with other particles and become much bigger than the starting powder particle size[11]. However, spatter particles do not always make it to the side of the build plate and redeposit on the build volume. Spatter particles have been directly correlated to the formation of lack of fusion (LOF) voids, among other process anomalies, characterized by inconsistent melting, forming irregular shaped voids[11]. This work investigates the processing of Ni282 by LPBF with attempts to induce process anomalies and potentially more LOF voids. A Ni282 build was set up with a high density of parts located near one another in attempts to induce process anomaly variations across the build volume. The experiment focused on spatter particle process anomalies because they were easy to identify with in-situ monitoring; however, the LOF void variation could Fig. 1 — Schematic of a typical LPBF build chamber as well as dramatization of the spatter particle formation.
ADVANCED MATERIALS & PROCESSES | MARCH 2025 13 be related to a number of process variations in the LPBF system. At this point, the authors are not able to confirm all the factors that led to variations in LOF void formation. Creep samples were machined from LPBF material and analyzed using x-ray computed tomography (XCT); samples were analyzed before and after creep testing to track void growth and potential new formation between samples with a low and high density of spatter particles. Optical microscopy was used to validate the XCT for smaller voids not in resolution of the instrument, and to distinguish the formation of voids at specific locations within the microstructure. SAMPLE FABRICATION Gas atomized Haynes Ni282 (UNS N07208) powder was acquired from Powder Alloy Corp. (Ohio, USA). The powder was processed with a Renishaw AM250 LPBF system (Wotton-under- Edge, UK), equipped with a 200 W, Yb-fiber laser. As shown in Fig. 2a, a four-inch-tall build was designed with a high density of material, including rods, plates, and thin walls. It is expected that samples farthest from the Ar inlet would be more susceptible to spatter particle deposition, than samples closer to the Ar inlet. Creep specimens were machined from the rods on the right and left sides of the build plate, labeled as T and C samples. Argon was flown from the inlet near the T samples, over the top of the build volume, to the outlet, closest to the C samples, as indicated by the arrow in Fig. 2a. Camera images were taken in-situ during the printing process of the powder volume as shown in Figs. 2b and 2c. Samples labeled C1 and C2, closest to the Ar outlet show a significant number of spatter particles, as indicated by the arrows in Fig. 2b, whereas the T1 and T2 samples near the Ar inlet only show signs of a few spatter particles as can be seen in Fig. 2c. More information on the Ni282 sample fabrication and preparation can be found elsewhere[13]. CREEP RESULTS The Ni282 creep specimens were subjected to a recrystallization heat treatment at 1180°C for 1 h, followed by a single step ageing treatment at 800°C for 4 h, per the recommendation following investigations of similar AM material[14]. Creep testing was performed on two T and C cylindrical threaded samples (6.36 mm in diameter gage section, 31.75 mm gage length) at 750°C, at 300 and 350 MPa, and creep curves are shown in Fig. 3. Two thermocouples were attached at the top and bottom grips to control the temperature within ±3°C. Creep curves were generated using two linear variable differential transformers (LVDT) connected to rods attached to the specimen heads. Overall, the T samples exhibited higher ductility, almost two times more than the C counterparts tested under each condition. A lower loading stress led to a longer creep life, but the ductility was consistent between the two testing conditions for both the T and C samples. CHARACTERIZATION OF VOIDS Before creep testing, the samples were examined using XCT in a Zeiss Metrotom system with an x-ray source of 200 kV. A short-scan strategy with 145 views between 0 and 197°, each view had an average 8×1 second acquisition, resulting in a scan time of 18 mins/scan. Advanced deep-learning algorithms[15] were used to reconstruct the void space for each sample, resolving any voids above ~75 µm with high confidence, although some smaller voids were still detected. Profiles from the XCT data on the T3 and C3 samples were processed to generate quantitative data on the various voids observed in the specimens, both in the reference state before testing and after rupture during creep testing. The ruptured samples were then crosssectioned after XCT, mounted in epoxy, and metallographically prepared down to a 0.05 µm finish with colloidal silica. A reference piece taken from the top of the rod before specimen machining was Fig. 2 — (a) Ni282 build investigated and camera images taken in-situ after melting mid-build of the (b) C samples closest to the Ar outlet and (c) T samples closest to the Ar inlet. Arrows in (b and c) indicate redeposited spatter particles[13]. Fig. 3 — Creep curves of T1 and C1 samples tested at 300 MPa, as compared to T3 and C3 tested at 350 MPa; testing temperature for both sets of specimens was 750°C. (a) (b) (c)
ADVANCED MATERIALS & PROCESSES | MARCH 2025 14 (a) (b) prepared in a similar manner. Optical characterization of the as-polished surfaces was performed with a Leica light microscope with up to 100 images captured automatically at 200× using Leica’s imaging software. The images were processed with a script that converts them to 8-bit files and uses shadow imaging to distinguish between the solid material and voids under grayscale; a threshold is applied, and the statistical data can be generated on all the observed voids. More information on the image analysis technique can be found in previous work[8]. Limitation in void size detectable by image analysis was <5 µm. Arguably, higher resolution optical images could be taken of the sample surfaces but would be more time consuming to focus and image across large cross-sections. Magnifications of 200× were chosen as the best compromise between resolution and imaging time. Comparisons of the number of voids detected by XCT and measured from image analysis of optical micro- scopy (OM) for reference and ruptured conditions is shown in Fig. 4; the frequency of voids shown was binned and then normalized by a factor of 100 for each data set to the maximum void frequency to be able to better compare the XCT data to that from OM. The maximum number of voids observed in the ruptured T3 and C3 samples from XCT was 11 and 196, respectively, whereas OM detected a maximum of 99 and 40 for the T3 and C3 ruptured samples, respectively. The T3 samples, being closest to the Ar inlet showed the least number of voids, as can be seen in Fig. 4a. The XCT resolved a small number of voids in the T3 reference material, <100 voids, with minor increases in number after creep testing in the ruptured sample. Optical image analysis from the reference material showed the presence of many small voids <25 µm in diameter that could not be detected by XCT. Moreover, the number of small voids increased after creep testing, most likely attributed to creep induced voids such as creep cavitation. The C3 sample, fabricated on the side of the build plate farthest from the Ar inlet and expected to have a higher number of redeposited spatter particles, exhibited a significantly higher number of voids, almost two times, in the reference sample, as analyzed by the XCT data and shown in Fig. 4b. After creep testing, there was an increase in magnitude in the number of larger voids 60-100 µm observed in the ruptured sample, and a decrease in the smaller voids <50 µm. Optical image analysis of the C3 reference and ruptured specimens showed a high concentration of smaller voids <50 µm and with no observation of larger voids. Since the OM data shown in Fig. 4 is reliant upon a single cross-section of the sample, it is understandable that detecting high frequencies of larger voids is unlikely to observed. XCT reconstructed 3D renderings of the creep specimens with voids and compressed cross-sections across a few millimeters near the fracture surface are shown in Fig. 5. 3D data from the XCT was used to register the approximate location, within 100 µm, of the reference as compared to ruptured condition. Registering the two conditions allows for tracking of the voids that likely led to fracture. Although some information is lost at the fracture surface where the two ends of the sample separated, locating likely suspects of failure is still reasonable. Note the smaller cross-section sizes in the ruptured conditions (Figs. 5b and 5d), a result of necking in the gage section. The T3 sample exhibited more ductility, as shown in Fig. 3a, and therefore, had a smaller cross-section after rupture than that of the C3 sample, as shown in Fig. 5d. As can be seen in Fig. 5a, two larger voids can be observed in the reference condition, near where the fracture surface is expected. After rupture, a significantly larger void is observed in the same spot as indicated by the arrows in Fig. 5b; additionally, other larger voids are also observed in the ruptured condition in Fig. 5b, signifying that many small voids <75 µm, either from the LPBF process or induced by creep cavitation, also coalesce. Similar behavior was observed be- tween the C3 reference and ruptured conditions in Fig. 5c and 5d, respectively, Fig. 4 — Quantification of voids detected from XCT and measured using image analysis of optical images for the (a) T3 and (b) C3 specimens before and after rupture. The frequency of voids was binned and then normalized by a factor of 100 for all data sets to better compare the magnitudes between XCT and OM.
ADVANCED MATERIALS & PROCESSES | MARCH 2025 15 although it is not as conspicuous. It is likely that multiple larger voids coalesced more readily in the C3 sample, and cannot be observed in Fig. 5d, as they are all along the fracture surface itself. MICROSTRUCTURAL CHARACTERIZATION XCT is a powerful tool for observation of the void space inside of additively manufactured material, or a specific component. Ideally, every component can be examined by XCT post-build as a qualification tool to determine the existence of any limiting process anomaly induced voids that could hinder the material’s performance. OM has been a verification tool for XCT at the smaller scale because process induced voids and voids from creep cavitation can coalesce and become larger problems. Optical image analysis requires destructive testing as samples must be sectioned for metallographic preparation, but can observe smaller features as well as give insight into their location in the microstructure. In LPBF, the types of voids observed in the microstructure can be broken down in three simplified categories: (1) spherical pores due to the vaporization of the melt, forming a keyhole with high penetration into the material that can potentially result in entrapped gas during solidification due to the fast solidification rates not providing the time for gas to escape; (2) irregular voids formed due to incomplete melting or lack of fusion (LOF); (3) line voids that are either related to cold or hot cracking from solute segregation or high residual strains that cannot be accommodated by the material, or another form of LOF voids[4]. Figure 6 shows the cross-section of the C3 sample near the fracture surface in the ruptured condition. In Fig. 6a, multiple voids including the three common types mentioned above (indicated by arrows), are observed. Many factors can cause incomplete melting and the formation of LOF voids, but it is likely that the high degree of spatter particles deposited on the C3 are the reason for numerous voids seen in Fig. 6a. Keyhole pores are stochastic and form depending on the local environmental conditions and the instantaneous behavior of the laser, making them unstable and difficult to predict. Therefore, keyholes are sporadically distributed throughout Fig. 6a. The chemically etched version of Fig. 6a is shown in Fig. 6b, where the irregular and line LOF voids appear to lie across multiple grains; keyhole pores are no longer easily distinguishable in the etched surface. Cracking formation during creep testing was observed to nucleate from both LOF voids, as shown in Fig. 6c, but expected creep damage was also observed, as seen in Fig. 6d. Even though LOF voids are stress concentrators that are conducive to cracking, stress fields still accumulated elsewhere, finding creep cavitation to still be a possibility in contributing to creep failure. SUMMARY The AMMT program has identified LPBF AM processing as a potential route for rapid qualification of new materials for use in nuclear reactor design. Process anomalies such as spatter particles can induce LOF voids that may adversely affect the mechanical performance of the material. To assess the impact of LOF voids on creep resistance, this study used LPBF to fabricate nickel superalloy 282 with a high density of components in a single build, to intentionally induce process anomalies that may cause LOF voids. In-situ monitoring revealed a higher Fig. 5 — 3D renderings with voids and compressed pseudo crosssections reconstructed from XCT data for the (a) T3 reference, (b) T3 ruptured, (c) C3 reference, and (d) C3 ruptured samples. The arrows indicated tracked voids that grew in size during creep testing, likely due to coalescence of smaller voids. Note: Change in diameter between the reference and rupture conditions is due to the necking of the gage section during creep testing. Fig. 6 — Optical images of the cross-section for the C3 sample near the gage section a er rupture, (a) as-polished and (b-d) a er chemical etching. Distinguishing between cracks nucleated from (c) LOF voids or (d) a result of creep deformation. (c) (d) (b) (a) (a) (b) (c) (d)
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