16 27 47 P. 11 Emerging Role of AI in Ceramic AM ASM Reference Publications & Digital Databases Catalog HTPro Newsletter Included in This Issue ANALYSIS OF TITANIUM SAMPLES MADE BY WIRE ARC DED ADVANCED MANUFACTURING SEPTEMBER 2024 | VOL 182 | NO 6
16 27 47 P. 11 Emerging Role of AI in Ceramic AM ASM Reference Publications & Digital Databases Catalog HTPro Newsletter Included in This Issue ANALYSIS OF TITANIUM SAMPLES MADE BY WIRE ARC DED ADVANCED MANUFACTURING SEPTEMBER 2024 | VOL 182 | NO 6
MAY 6–8, 2025 | VANCOUVER, CANADA 36th AeroMat Conference and Exposition INNOVATIONS IN MATERIALS ENGINEERING: SHAPING THE FUTURE OF THE AEROSPACE INDUSTRY 2025 aeromatevent.org New innovations in materials engineering are required to deliver improvements in the performance, cost, and environmental impact of aerospace structures and engines. The 2025 technical program will focus on the latest aerospace materials and process developments, with keynotes and panels to feature Canadian-centric projects and collaborations with the global materials community. SAVE THE DATE! ORGANIZED BY CO-LOCATED WITH:
44 IMAT 2024 SHOW PREVIEW IMAT—the International Materials, Applications & Technologies Conference and Exhibition—and ASM’s annual meeting will be held in Cleveland, September 30 to October 3. EXPLORING THE TENSILE-COMPRESSIVE ASYMMETRY OF TITANIUM SAMPLES MADE BY WIRE ARC DIRECTED ENERGY DEPOSITION Blanca Palacios, Tanaji Paul, Arvind Agarwal, and Sean Langan This entry won first place in the light microscopy category of the prestigious 2023 International Metallographic Contest. 11 ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 2 Optical micrograph of deformed profilometry-based indentation plastometry sample using polarized light and DIC microscopy. On the Cover: 62 ASM NEWS The latest news about ASM members, chapters, events, awards, conferences, affiliates, and other Society activities. ASM REFERENCE PUBLICATIONS & DIGITAL DATABASES CATALOG Our vast, authoritative reference library offers the most comprehensive and up-to-date materials information. 27
4 Editorial 5 Machine Learning 6 Metals/Polymers/Ceramics 8 Testing/Characterization 10 Emerging Technology 71 Editorial Preview 71 Special Advertising Section 71 Advertisers Index 72 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. 182, No.6, SEPTEMBER 2024. Copyright © 2024 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: 700 Dowd Ave., Elizabeth, NJ 07201. Printed by Kodi Collective, Lebanon Junction, Ky. 16 THE EMERGING ROLE OF AI IN CERAMIC ADDITIVE MANUFACTURING Bhargavi Mummareddy and Kalyan Immadisetty The integration of artificial intelligence for predictive modeling and adaptive learning allows manufacturers to achieve unprecedented levels of e iciency and precision in ceramic AM products. 20 ASM HISTORICAL LANDMARK SERIES PITTSBURGH CHAPTER HONORS HENRY CLAY FRICK’S BIRTHPLACE The springhouse home of one of the most significant pioneers in the coke and steel industries is dedicated as a 2024 ASM Historical Landmark. 22 CELEBRATING 25 YEARS OF MATERIALS CAMPS Twenty-five years ago, the ASM Materials Education Foundation created a dynamic educational camp to bridge the gap between academia and industry, inspiring the next generations of scientists and engineers. FEATURES SEPTEMBER 2024 | VOL 182 | NO 6 ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 3 16 The ASM Foundation transforms classrooms into dynamic spaces where theory meets practice. By empowering educators and inspiring students, we shape the STEM workforce by encouraging thousands of young people to explore materials science and consider careers in engineering, manufacturing, and technical fields. We are dedicated to fostering a brighter future in materials science and engineering. Transforming Education Global Impact The ASM Materials Education Foundation has influenced over 13,000 teachers, introduced 1.1 million students to materials science, and awarded over $2.5 million in scholarships. With 42 camps nationwide and growing, the Foundation aims to reach every state by 2030 giving all students opportunities in materials science and engineering. 2024 22 47 20 47 HTPro The official newsletter of the ASM Heat Treating Society. This supplement focuses on heat treating technology, processes, materials, and equipment, and features a preview of the International Federation for Heat Treatment and Surface Engineering World Congress, held in Cleveland from September 30 to October 3.
4 ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 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 Press Release Editor magazines@asminternational.org EDITORIAL COMMITTEE John Shingledecker, Chair, EPRI Beth Armstrong, Vice Chair, Oak Ridge National Lab Adam Farrow, Past Chair, Los Alamos National Lab Rajan Bhambroo, Tenneco Inc. 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 Bhargavi Mummareddy, Dimensional Energy Scott Olig, U.S. Naval Research Lab Christian Paglia, SUPSI Institute of Materials and Construction Amit Pandey, Lockheed Martin Space Satyam Sahay, John Deere Technology Center India Kumar Sridharan, University of Wisconsin Vasisht Venkatesh, Pratt & Whitney ASM BOARD OF TRUSTEES Pradeep Goyal, President and Chair Navin Manjooran, Senior Vice President Elizabeth Ho man, Vice President Mark F. Smith, Immediate Past President Lawrence Somrack, Treasurer Amber Black Ann Bolcavage Pierpaolo Carlone Hanchen Huang André McDonald Christopher J. Misorski U. Kamachi Mudali James E. Saal Dehua Yang 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. INFLUENCING THE FUTURE Long before the first profile was posted on Facebook and the first video was uploaded to TikTok, ASM was positively impacted by our own brand of “influencers”—in the very best sense of the word. Don Baxter, Al Kay, FASM, TSS-HoF, and Roger Jones, FASM, are all highlighted in the “In Memoriam” section of this issue. All three were champions for ASM in their own way. Don was the managing editor of AM&P magazine and several other publications during his long career as an ASM staff member, before retiring in 2008. He taught me the guidelines for article preparation and issue layout. Today, our magazine team is known to spout “Don-isms’’—reciting his preferences for styling an equation or wording an image caption. His editing pencil was always sharp, and always correct. He was a true mentor, often taking time out of his day to explain an intricacy of a specific publishing best practice. We had the opportunity to work together at the magazine booth during several ASM events. I appreciated learning firsthand that he viewed those conferences not only as vehicles for sharing technical information, but as places to nurture relationships and strengthen professional bonds—to build up the ASM family. Al Kay had incredible financial acumen. He served on several boards and committees for the Thermal Spray Society, ASM at large, and the ASM Foundation in roles where he used his quick mind and keen business sense for the betterment of the Society. Roger Jones was a true leader in both the Heat Treating Society and ASM International, in word and deed. If Roger supported an idea or a cause, he could build consensus and others followed. These examples show the power of a life lived in service of the greater good. Don, Al, and Roger all looked to the future and shared their vast experience to prepare the next generation. Similar knowledge sharing will happen at IMAT 2024 in Cleveland in several ways, but most pointedly during the Emerging Professionals symposium. A lineup of invited speakers will provide advice to those early in their careers. And a new “office hours” program will offer a venue for young people to receive guidance on resume preparation and career strategies. Also at IMAT, the 2024 Class of Fellows will be inducted. The 16 new Fellows are featured in this issue’s ASM News section. These distinguished members are being recognized for their contributions to materials science and engineering as well as the Society. They join an illustrious group of existing Fellows, representing various areas of our industry, who serve as professional leaders and advisors to the Society. But it’s not just the ASM Fellows who can make an impact. Every ASM member can be a role model in their own way. At IMAT and in your career, bring along the next generation: teach, mentor, support, and build relationships. Look to the future and use your influence to make the outlook of the materials industry, and ASM, brighter. joanne.miller@asminternational.org Joanne Miller with Don Baxter, fall 2006.
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 5 MACHINE LEARNING | AI NEW STANDARD COVERS AI FOR MATERIALS A prerequisite for artificial intelligence (AI) in materials research is largescale use and exchange of data on materials, which is facilitated by a broad international standard. A major international collaboration has developed an extended version of the OPTIMADE standard. Many demanding simulations are now performed on supercomputers that describe how electrons move in materials, giving rise to different properties. These advanced calculations yield large amounts of data that can be used to train machine learning models. These AI models can then predict responses to new calculations that have not yet been made, and by extension predict the properties of new materials. However, huge amounts of data are required to train the models. “We’re moving into an era where we want to train models on all data that exist,” says researcher Rickard Armiento of Linköping University, Sweden. Data from large-scale simulations, as well as general data about materials, are collected in large data- bases. Many such databases have emerged over time from various research groups—all working differently and using properties defined in numerous ways. The OPTIMADE (open data- bases integration for materials design) standard has been developed over the past eight years. Behind the standard is a large international network with over 30 institutions worldwide and large materials databases in Europe and the U.S. The goal is to give users easier access to both leading and lesser-known materials data- bases. A new version of the standard (v1.2) is now being released and is described in an article published in Digital Discovery. One of the biggest changes in the new version is a greatly enhanced ability to accurately describe different materials properties and other data using common definitions. The collaboration spans the EU, U.K., U.S., Mexico, Japan, and China. www.liu.se. ALGORITHM DESIGNS OPTICAL FILMS OptoGPT, developed by engineers at the University of Michigan, employs the computer architecture underpinning ChatGPT to work backward from desired optical properties to the material structure that can provide them. The new algorithm designs optical multilayer film structures that can serve a variety of purposes. Well-designed multi- layer structures can maximize light absorption in a solar cell, optimize reflection in a telescope, and improve semiconductor manufacturing with extreme UV light. From left, Oskar Andersson and Rickard Armiento work on supercomputers at Linköping University to simulate how atoms in different materials behave. OptoGPT produces designs for multilayer film structures within 0.1 seconds. In addition, the algorithm’s designs contain six fewer layers on average compared to previous models, making its results easier to manufacture. To automate the design process for optical structures, the research team tailored a transformer architecture— the framework used in large language models like OpenAI’s ChatGPT—for their own purposes. The model treats materials at a certain thickness as words, also encoding their associated optical properties as inputs. Seeking out correlations between these “words,” the model predicts the next word to create a “phrase”—in this case a design for an optical multilayer film structure—that achieves the desired property such as high reflection. Researchers tested the new model’s performance using a validation dataset containing 1000 known design structures including their material composition, thickness, and optical properties. When comparing OptoGPT’s designs to the validation set, the difference between the two was only 2.58%, lower than the closest optical properties in the training dataset at 2.96%. umich.edu. OptoGPT’s process combines an undetermined layer’s possible materials and thicknesses into a format that can be run through the program to choose the best possible combination. Courtesy of L. Jay Guo Laboratory.
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 6 METALS | POLYMERS | CERAMICS According to a new report from MarketsandMarkets Research, the metal recycling market is projected to grow from $551.9 billion in 2024 to $767.9 billion by 2029 at a CAGR of 6.8%. Metal recycling involves converting both ferrous and non-ferrous scrap into new products. marketsandmarkets.com. a pathway to make new titanium alloys with exceptional combinations of strength and ductility. The team tailored the chemical composition and lattice structure of the alloys while also adjusting processing techniques for producing the material at industrial scale. The improvements could have applications in the aerospace sector. Titanium alloys have been important because of their exceptional mechanical properties, corrosion resistance, and light weight when compared to steels, for example. The structure of titanium alloys, all the way down to atomic scale, governs their properties. Through careful selection of the alloying elements and their relative proportions, scientists can create various structures, allowing for different property combinations—both for cryogenic and elevated temperatures. In addition to choosing the right alloying materials and proportions, the team found, steps in the materials processing turned out to play an important role. A technique METAL-INSULATOR SUPERCRYSTAL DISCOVERY A research team led by Cornell University, Ithaca, N.Y., discovered a supercrystal formation previously unobserved in a metal-insulating material, potentially unlocking new ways to engineer materials and devices with tunable electronic properties. The researchers showed that the atomic structure in the thin-film Mott insulator Ca2RuO4—part of a unique family of materials that can switch between being a metal and an insulator due to quantum effects—forms an anisotropic, organized pattern with multiple spatial periods below temperatures of 200 to 250 K. Previously, the group developed an analysis technique combining high-powered x-rays, phase-retrieval algorithms, and machine learning that could provide a real-space visualization of materials at the nanoscale. This technique revealed a new type of straininduced nanopattern that spontaneously forms in Ca2RuO4 during cooling to cryogenic temperatures. By zooming out, the latest research showed that the 10-nanometer structure was embedded in a larger supercrystal. The versatile control capabilities of Mott insulators make them ideal materials for various applications, including memory elements and optical switches. Switchable structures such as the supercrystal state in Ca2RuO4 could offer a powerful means of influencing the energy balance between competing ground states, according to the researchers. They also say this switch in the preferential direction of the current gives them a new means of controlling technologically relevant properties, potentially not just in this material, but in others as well. cornell.edu. DESIGNING STRONGER TITANIUM ALLOYS A collaborative group of researchers from Massachusetts Institute of Technology, Cambridge, working with ATI Specialty Materials, Dallas, discovered Mango Materials, Redwood City, Calif., developed a new process to convert methane into polyhydroxyalkanoate, which can be compounded into 100% biodegradable polyester pellets to form durable goods, fabrics, and flexible films. mangomaterials.com. BRIEFS Depiction of x-ray nanodi raction and local resistivity measurements shedding light on a novel supercrystal state. Courtesy of Oleg Gorobtsov. A new method for creating titanium alloys could lead to unprecedented strength and ductility.
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 7 called cross-rolling is another key to achieving the exceptional combination of strength and ductility. Working together with ATI researchers, the team tested a variety of alloys under a scanning electron microscope as they were being deformed, revealing details of how their microstructures respond to external mechanical load. They discovered that there was a particular set of parameters— composition, proportions, and processing method—that yielded a structure where the alpha and beta phases shared the deformation uniformly, mitigating the cracking tendency that is likely to occur between the phases when they respond differently. The analysis and experimental results of the new design approach provide guidance for producing materials that meet the needs of specified applications. mit.edu. MAKING SPACE BRICKS WITH MICROWAVES Researchers at the Korea Institute of Civil Engineering and Building Technology (KICT) developed a new method for producing construction materials using in-situ resources from the moon. Utilizing microwave sintering, the research team produced blocks from lunar regolith—the moon’s surface soil and its most readily available in-situ resource. When using microwaves to heat lunar regolith, localized hot and cold spots can form. These spots lead to localized thermal runaway, hindering uniform heating and sintering. To address this, the researchers established a stepwise heating method with specific temperature and dwell time. Another challenge the team addressed was lunar regolith’s inherent volatile substances, including water. Heating these volatile materials can cause internal cracks during sintering. The researchers mitigated crack formation by using preheated lunar regolith simulant under vacuum conditions at 250°C. To assess the completeness of sintered blocks intended for construction materials, researchers core-drilled the resulting blocks at specific locations within the material. The average density, porosity, and compressive strength of the core-drilled samples were approximately 2.11 g/cm , 29.23%, and 13.66 MPa, respectively. The corresponding standard deviations were 0.03, 1.01, and 1.76, confirming the homogeneity of the sintered blocks. The team’s next step is to validate this technology in space environments. www.kict.re.kr. Space brick shown via photography (le ) and x-ray CT scan (right). Courtesy of KICT. STAY AHEAD OF YOUR PROFESSIONAL JOURNEY WITH ASM EDUCATION & TRAINING. EARN CEUs, ENJOY DISCOUNTS, NETWORK, AND LEARN FROM INDUSTRY EXPERTS. SCAN TO ENROLL TODAY Education
8 ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 Sydney in New South Wales, a new microscopy method can decode atomic relationships within materials and could open possibilities for next- generation design. The new technique allows researchers to detect tiny changes in the atomic-level architecture of crystalline materials—like advanced steels for ship hulls and custom silicon for electronics. The breakthrough could assist in the development of stronger and lighter alloys for the aerospace industry, new generation semiconductors for electronics, and improved magnets for electric motors. It could also enable the creation of sustainable, efficient, and cost-effective products. The team harnessed the power of atom probe tomography (APT) to unlock the intricacies of short-range order (SRO). The SRO process is key to understanding the local atomic environments essential for development of innovative materials which could underpin a new generation of alloys and semiconductors. SRO is sometimes likened to the materials genome— the arrangement or configuration of TESTING | CHARACTERIZATION FRACTURE MECHANISM IN SOFT MATERIALS REVEALED Researchers led by a team at the Polytechnic University of Milan developed a new theory they say has finally deciphered the physical mechanisms of fracture in soft materials. The discovery could lead to new, defect-free materials that are more resistant and durable as well as environmentally friendly. This discovery stimulates significant applications in various technological sectors —for instance, in the production of micro and nanodevices, where materials need to be extremely resistant and defect-free. “We have revealed that fracture propagates from the free surface of the material, starting from an elastic instability that breaks the symmetry of the object,” explains researcher Pasquale Ciarletta. “Then, the rupture drastically extends with an intricate network of cracks spreading like a turbulence phenomenon similar to what we observe in fluids, like during vortex formation.” In the consumer electronics field, this could lead to the creation of devices such as smartphones, tablets, and laptops with screens that better withstand shocks and drops, thus reducing the frequency of repairs and replacements. In the medical sector, implantable devices like pacemakers and prostheses could benefit from safer and longer-lasting materials, critically improving patient health. In the aerospace industry, understanding and preventing material fractures can lead to more robust and reliable structures, reducing the risks associated with space and air travel. www.polimi.it/en. DECODING ATOMIC RELATIONSHIPS Developed by a research team at the University of Triangular holes make this material more likely to crack from left to right. Courtesy of N.R. Brodnik et al./Phys. Rev. Lett. Leica Microsystems Inc. recently celebrated its 175th anniversary. In 1849, Carl Kellner founded the Optical Institute in Wetzlar, Germany, making instruments with a new type of eyepiece that significantly reduced distortion. Ernst Leitz I soon took over the business, with several generations of the Leitz family making contributions for decades. Leica joined the Danaher Group in 2005. leica-microsystems.com. In June, Zeiss opened its new Innovation Center in Hsinchu Science Park, Taiwan. The facility offers a comprehensive equipment mix to meet the needs of semiconductor R&D, production, and failure analysis in Taiwan. zeiss.com. BRIEFS Simulated 2D atomic images from atom probe. Courtesy of University of Sydney. Depiction of surface instability showing the reference and actual configurations, while also detailing the nature of the boundary conditions. Courtesy of Physical Review Letters, 2024, DOI: 10.1103/PhysRevLett.132.248202.
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 9 atoms within a crystal. This is significant because different local atomic arrangements influence the electronic, magnetic, mechanical, optical, and other properties of materials, which have a bearing on the safety and functionality of a range of products. Until now, SRO has been challenging for researchers to measure and quantify because atomic arrangements occur at a scale so small that they are difficult to see with conventional microscopy techniques. The new method, using APT, overcomes these challenges, paving the way for advances in materials science that could have far-reaching implications in a range of industries. Critically, the study enhances the capabilities of researchers to computationally simulate, model, and ultimately predict materials behavior with SRO providing the detailed atomicscale blueprint. www.sydney.edu.au. FORMING RARE EARTH ELEMENTS Scientists have discovered how the rare mineral fluocerite quickly forms and transforms into bastnaesite, a crucial mineral for the extraction of rare earth elements (REEs). Researchers from Trinity College Dublin revealed this novel route to the formation of bastnaesite, advancing the progress toward making the extraction of these REEs more efficient. The research team revealed a new crystallization path that produces extremely tiny, nanometricsized minerals. Some of these elusive minerals are incredibly small, just a few billionths of a meter in size, making them very difficult to observe in natural samples. Their research found that fluocerite can act as a seed to promote the rapid formation of bastnaesite. REEs are vital for a wide range of technologies, from smartphones to renewable energy solutions. They are also crucial for researchers who have struggled to understand the intricate factors and pathways involved in the formation of these tiny, nanometric minerals. The researchers say their discovery was made by following a completely different approach—they built synthetic bastnaesite rocks in the laboratory to mimic the same processes occurring in nature—and studied them with powerful spectroscopic and microscopic techniques. According to the researchers, their insights are crucial for developing better industrial methods for extracting rare earth elements. www.tcd.ie. Images of fluocerite and bastnasite. Courtesy of Rodriguez-Blanco/Trinity College Dublin.
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 10 RECYCLING UNSATURATED POLYMERS WITH OXYGEN AND LIGHT Researchers at The University of Akron, Ohio, developed a novel method to recycle unsaturated polymers such as rubber and plastics. The new process uses oxygen and light to help break down the polymers naturally. Since the 1950s, the mass production of plastics has resulted in the creation of approx- imately 8.3 billion metric tons of polymers. Most of these polymers have been discarded or incinerated, leading to significant environmental contamination. Only 600 million metric tons have been effectively recycled. The stability and durability of commercial polymers, particularly polyolefins—which constitute over half of global polymer production—present significant recycling challenges due to their hydrocarbon backbone. The new research focuses on introducing unsaturation to enhance the reactivity of these polymers, thus facilitating their recycling. Traditional methods for oxidative cleavage of alkenes, such as ozonolysis, epoxidation, and permanganate oxidation, while effective, often require environmentally unfriendly, energy-intensive conditions that are difficult to scale up. This study pioneers a controlled, efficient method for breakdown using a catalyst that, when activated under light, successfully breaks down the polymers at room temperature without requiring elevated temperatures or pressures. This research not only enhances our understanding of polymer degradation but also provides a practical, scalable solution for recycling unsaturated polymers. uakron.edu. STRONGER AND LONGER METALLIC MATERIALS A research team from Pohang University of Science and Technology (POSTECH), South Korea, and Northwestern University, Evanston, Ill., introduced a groundbreaking technology that enhances both high strength and high elongation in metallic EMERGING TECHNOLOGY materials. The new approach incorporates spinodal decomposition, where a solid solution spontaneously separates into two distinct phases, resulting in nanoscale structures with regularly arranged atoms. The scientists added copper and aluminum to an iron-based medium- entropy alloy to trigger periodic spinodal decomposition at the nanoscale. This process led to spinodal hardening, a phenomenon that enhances resistance to structural deformation. The resulting microstructure, with its uniformly arranged features, effectively distributes strain throughout the material. This distribution helps minimize localized deformation, thereby increasing overall strength while preserving elongation. Experiments revealed that alloys produced using the team’s method demonstrated superior structural integrity compared to traditional alloys, achieving a yield strength of 1.1 GPa. Remarkably, even with this increased yield strength, the alloy maintained nearly the same elongation (28.5%) as before. This advancement enables both improved strength and elongation. international.postech.ac.kr, northwestern.edu. A new tool called 4Pi from General Atomics (GA), San Diego, is helping to optimize the targets used in inertial confinement fusion experiments. Including the first ignition in December 2022, each of the five successful ignitions at the National Ignition Facility has used a target characterized by 4Pi. The tool combines up to eight instruments within one system, including robotics, automation, batch evaluation, and machine learning. ga.com. BRIEF A graphical depiction of a novel process for breaking down polymers. Courtesy of University of Akron. Analysis of spinodal decomposition and strengthening using nano-atomic-scale analysis. Courtesy of POSTECH.
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 1 1 This entry won first place in the light microscopy category of the prestigious 2023 International Metallographic Contest. *Member of ASM International EXPLORING THE TENSILE-COMPRESSIVE ASYMMETRY OF TITANIUM SAMPLES MADE BY WIRE ARC DIRECTED ENERGY DEPOSITION LIGHT MICROSCOPY Blanca Palacios,* Tanaji Paul,* and Arvind Agarwal, FASM* Florida International University, Miami Sean Langan Solvus Global, Worcester, Massachusetts
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 12 Wire arc directed energy deposition (WDED) offers a robust alternative for metal printing on a large scale with high deposition rates of up to 9.5 kg/hr[1]. WDED achieves excellent material and energy efficiency, boasting a rate of over 90% and significantly reducing wasted material compared to conventional manufacturing processes such as casting and machining. However, investigating WDED involves several processing para- meters and boundary conditions that must be thoroughly navigated to comprehend their impact on the microstructural characteristics and materials properties. The inherent phase transformations and complex thermal history cycles along with robotics tool planning can introduce anisotropy, underscoring the importance of a deeper scientific understanding of WDED to unlock its full potential in metal production. Optical microscopy can assist in this effort. Commercially pure titanium (cp-Ti) is a notable candidate for WDED due to its remarkable properties, including high yield strength (~180-480 MPa), low specific weight (4.5 g/cm3), and excellent corrosion resistance. These attributes have long positioned cp-Ti as a material of choice across diverse industries from aerospace to automotive to chemical applications. However, as demand for large-scale additive manufacturing of complex components continues to rise, it becomes imperative to grasp the intricate interplay between manufacturing processes and the resulting microstructure and mechanical properties of WDED cp-Ti. Investigating the mechanical properties of anisotropic WDED cp-Ti has underscored the importance of comprehending plastic deformation across different conditions. When subjecting samples to tension and compression (along the same direction), different stressstrain curves are often obtained, a phenomenon known as tensile- compressive asymmetry (TCA)[2]. The present study employs standard and advanced techniques to derive stress-strain curves, coupled with optical microscopy, to investigate the behavior of WDED cp-Ti under tension and compression. MATERIAL PROCESSING AND EXPERIMENTAL METHODS A 1-mm diameter cp-Ti wire with a chemical composition of 99.8 Ti, 0.14 O, 0.04 Fe, 0.003 N, 0.008 C, and 0.002 H wt% was used for the wire arc directed energy deposition. The 3D printed block resulted from the deposition of eight vertical layers overlapping each other on the substrate and 16 parallel tracks using a raster pattern (Fig. 1a). Analysis was conducted along the build direction because the current study focuses on understanding the thermal gradient’s effect on the mechanical response of the bulk. Deformation mechanisms were investigated along the samples after testing subjected them to tensile and compressive (indentation) loads. Uniaxial tensile tests were conducted at room temperature according to the ASTM E8/E8M standard on a universal testing machine (MTS Criterion Model 43) with a calibrated load cell of 30 kN. Tests were performed in displacement controlled mode at a 0.1 mm/min rate. Yield strength was calculated at a 0.2% offset strain. A novel indentation technique, profilometry-based inden- tation plastometry (PIP), was implemented to subject the samples to compressive stresses. The employed indentation plastometer (Plastometrex, version 1.0) is comprised of multiple components: a silicon nitride spherical 1-mm radius indenter, a linear variable differential transducer (LDVT) with 0.3 µm resolution, a Taylor Hobson (Talysurf) profilometer including a contacting stylus with 0.4 µm resolution, a 9 kN load cell with accuracy to 0.1 N, and Corsica 4.0 software to conduct calculations and generate the stress-strain curves[3]. PIP uses the material’s elastic properties, maximum indentation load, and residual indent profiles to feed into the model. In this way, the elastic constants that represent the material’s elastic behavior, load displacement response, and residual indent profiles that describe the plasticity response of the material are integrated into the FEM model, which uses the Voce plasticity equation for the iterations. In this equation, σs is the von Mises equivalent stress, σy denotes the current yield stress, and (-ε/ε0) denotes the equivalent plastic strain. Plasticity parameters are adjusted iteratively in the FEM simulation to mimic the indentation test. Optimal convergence is reached, yielding best-fit plasticity parameters. True stress and strain values reflecting the material’s plasticity are also derived. Finally, stress-strain curves for a representative volume are obtained from the processed FEM model. The general schematic of the PIP is presented in Fig. 2. Fig. 1 — Schematic of (a) bulk commercially pure titanium deposit, sample locations, and orientation; (b) macro image of reference dog bone sample for uniaxial tensile test acquired using a 6K resolution camera; and (c) polarized light microscopy stitched images of reference sample for PIP indentation. (a) (b) (c)
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 13 Samples were machined from the bulk WDED cp-Ti using a high-speed diamond saw (Allied High Tech Products, TechCut 5x) for the PIP indentation all along the building direction; indentation locations are shown in Fig. 1a. Modified sub-size (ASTM E8) tensile test specimens were machined using wire electrical discharge machining to ensure precision of the dogbone shape; samples along the buildup are shown in Fig. 1a. Metallography preparation was conducted manually using a rotary polishing wheel at 40-120 RPM. Silicon carbide papers with grit sizes of 400 and 600 [ANSI] were used for grinding. A chemical-mechanical procedure was used with a 7:2:1 mixture of 0.05 µm amorphous colloidal silica suspension, H2O2 with a concentration of 30%, and Kroll’s reagent for polishing to achieve a mirror finish free of deformations. Residual particles were removed through ultrasonic cleaning in methanol for 15 minutes. Microscopic imaging of the samples (before and after uniaxial tensile and PIP tests) was performed using optical microscopy (Axioscope 5, Carl Zeiss Microscopy) along with ZEN core 3.3.92 software for image acquisition. Polarized light microscopy (PLM) and differential interference contrast (DIC) microscopy were used to capture images of deformed grains from the unetched surfaces. Reference images from undeformed tensile and PIP samples are shown in Figs. 1b and 1c, respectively. After testing, images were post-processed in Adobe Photoshop to highlight regions of the deformed twins. Next, the twinned area fraction was computed using ImageJ open-source software. RESULTS AND DISCUSSION Combining metallography sample preparation with optical microscopy techniques enabled microstructural characterization and revealed deformation mechanisms along the WDED cp-Ti buildup. It was observed that the solidified microstructure of the pristine material exhibited a monolithic bimodal grain size (≈1 mm coarse grains with nested finer grains) distribution of alpha-phase titanium (α-Ti), which is characterized by its hexagonal close-packed (HCP) structure[4]. HCP structures enable microscopy observation under polarized light even after Fig. 2 — Schematic of PIP technique for plasticity characterization: This combines the material’s elastic properties, residual indent profiles, and mathematical models implementing the Voce equation and FEM to iterate calculations that result in the generation of stress-strain curves.
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 14 severe deformation on the surface. PLM detects c-axis orientation in relation to the incident light direction and vibration plane. According to the generalized Fresnel equations, incident light splits into two refracted (or reflected) waves, each polarized differently and with distinct refractive indices. Upon exiting the sample, these waves interfere destructively, causing color changes. As the Michel-Levy birefringence inter- ference color chart indicates, these colors depend on sample thickness and birefringence value[5]. Rotating crystals on the microscope stage can adjust their color appearance accordingly. Representative PLM images of the deformed surface of WDED cp-Ti tensile test samples after fracture are shown in Fig. 3. Loading direction with respect to the sample is represented in the Fig. 3a inset. Large deformed regions arise from plastic deformation caused by dislocation glide, which leads to strain accumulation and localized deformation within the material, as shown in Figs. 3a and 3b. However, plastic deformation by slipping of WDED cp-Ti is limited due to its low symmetry and reduced number of independent slip systems. Thus, nucleation of twinning deformation occurs to accommodate complete deformation along the c-axis direction when the <a> or <c + a> are limited. Contrary to slip dislocation, twinning dislocations are characterized by shearing and reorientation of one segment of the crystal lattice. As mentioned, PLM interacts with grains with respect to the c-axis angles. Next, the microscope’s analyzer plate angle was rotated to facilitate visualization of the twin planes on the surface and differentiate them from the slip planes (Fig. 3c). PIP indentation of the samples along the buildup shows a large deformation in the vicinity of the indent (Fig. 4). PIP has the ability to provide accurate stress-strain curves that enable calculation of tensile- compressive asymmetry (TCA)[6]. Twin planes are present all around the vicinity of the indent with slip planes nested in between (Fig. 4a). PLM and DIC techniques were combined to characterize the larger twin regions (Fig. 4b). Formation of secondary twins was evidenced as presented in Fig. 4c. In this case, the primary twin acts as a parent grain and allows formation of the secondary twin due to the affinity of its orientation to be deformed again under stress. This phenomenon can be attributed to the complex loading condition that results beneath the indent from the PIP indentation, which is graphically described in the Fig. 4a inset[7]. Stress-strain curves from both the tensile and PIP tests were overlapped and used to compute the mechanical properties of the material under both conditions (Fig. 5). Yield stress (σy) demonstrated comparability with a low TCA percentage, approximately 8%, indicating a more uniform strain during the initial plasticity stage. On the other hand, ultimate tensile strength (UTS) exhibited around 37% TCA, with higher values observed when employing the PIP technique. This suggests that the intricate compressive stresses induced by the indenter interact with the compressive residual stresses of the overlapped WDED layers, alongside the influence of predetermined grain misorientation, which is susceptible to deformation via twinning[8]. The role of twin deformations in the plastic behavior of WDED α-Ti, especially in the work hardening region, is evident and contributes to the observed significant tensile-compressive asymmetry of the UTS. Multiple optical micrographs from both tensile and PIP tests were processed into 16-bit grayscale and edited to highlight twin regions in order to support the current study’s findings. A fixed threshold of 30% was applied to calculate the approximate twinned area fraction of the characterized images (Figs. 6a and 6b). Fig. 4 — Optical micrographs of deformed PIP samples using polarized light and DIC microscopy for characterizing slip and twin planes on the indent’s vicinity. Fig. 3 — Optical micrographs of deformed tensile test samples using polarized light at different angles of the analyzer plate. Different c-axis angles react to various contrasts, allowing identification of individual grains, morphology, and features as slip planes and twins. (a) (b) (c) (a) (b) (c)
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 15 The average twinned area fraction was 3.99 ± 2.8% and 4.55 ± 0.9% from the tensile test and PIP images, respectively. The larger twinned area fraction is observed in the PIP case, impacting the hardening capacity of WDED α-Ti at room temperature. Hence, the increased twin boundary density acts as a low- energy grain boundary, not blocking but reducing dislocation movement on the material. CONCLUSIONS The tensile-compressive asymmetry of single phase WDED α-Ti along the buildup was characterized by comparing experimental data from the uniaxial tensile test and the PIP technique. The combination of experimental results and optical microscopy techniques resulted in a characterization of the main deformation mechanisms under tensile vs. compressive stresses at room temperature. Samples exhibited two prominent deformation mechanisms: twinning and slip dislocations. Twins significantly influenced the material’s plasticity behavior, particularly its hardening capacity. Mechanical properties from the PIP resulted in higher UTS, which is primarily attributed to larger twin density. The larger formation of twins under compression emerges primarily from the complex stress condition under the indent and interaction with the compressive residual stresses resulting from multiple deposited layers on the buildup. ~AM&P For more information: Blanca Palacios, Ph.D. researcher, Cold Spray and Rapid Advanced Deposition Laboratory, Florida International University, 10555 W. Flagler St. EC 2400, Miami, FL 33174, 305.348.0198, bpala021@fiu.edu. References 1. A. Queguineur, et al., Wire Arc Additive Manufacturing of Thin and Thick Walls Made of Duplex Stainless Steel, Int. J. Adv. Manuf. Technol., 127, p 381-400, 2023, doi.org/10.1007/s00170- 023-11560-5. 2. J. Suryawanshi, et al., Tensioncompression Asymmetry and Shear Strength of Titanium Alloys, Acta Mater., 221, p 117392, 2021, doi.org/10.1016/ j.actamat.2021.117392. 3. D. John, et al., Profilometry-Based Indentation Plastometry for Evaluating Bulk Tensile Properties of AluminumSilicon Carbide Composites, Adv. Eng. Mater., 25(14), p 2201890, 2023, doi.org/ 10.1002/adem.202201890. 4. B. Palacios, et al., Role of Structural Hierarchy on Mechanics and Electrochemistry of Wire Arc Additive Manufactured (WAAM) Single Phase Titanium, J. Manuf. Process., 93, p 239249, 2023, doi.org/10.1016/j.jmapro. 2023.03.025. 5. L. Böhme, et al., Crystal C-axis Mapping of HCP Metals by Conventional Reflected Polarized Light Microscopy: Application to Untextured and Textured cp-Titanium, Mater. Charact., 145, p 573581, 2018, doi.org/10.1016/j.matchar. 2018.09.024. 6. Y.T. Tang, et al., Tensile-Compressive Asymmetry in Extruded AZ31B Rod and Its Effect on Profilometry-based Indentation Plastometry (PIP), Mater. Sci. Eng. A, 848, 2022, doi.org/10.1016/ j.msea.2022.143429. 7. A. Lama, et al., Macroscale Property Assessment and Indentation Characteristics of Thick Section Friction Stir Welded AA 5083, Mater. Sci. Eng. A, 880, p 145306, 2023, doi.org/10.1016/ j.msea.2023.145306. 8. F. Azarmi and I. Sevostianov, Evaluation of the Residual Stresses in Metallic Materials Produced by Additive Manufacturing Technology: Effect of Microstructure, Curr. Opin. Chem. Eng., 28, p 21-27, 2023, doi.org/10.1016/ j.coche.2019.12.004. Fig. 5 — Stress-strain curves resulting from the uniaxial tensile tests and PIP tests show the estimated anisotropy behavior of the WDED cp-Ti plasticity response. Fig. 6 — Optical micrographs of (a) tensile and (b) PIP samples used for the twinned area fraction calculations. Images were converted into 16 bits (grayscale pixels), twin regions were enhanced in Photoshop, and a threshold of 30% (darker shades/black) was used in ImageJ software to allow calculations under the same conditions. (a) (b)
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 16 Additive manufacturing (AM) has transformed the manufacturing landscape exponentially. The process begins with creating a digital model using computer-aided design (CAD), slicing it into thin layers, and converting these layers into printable instructions for AM equipment. Using a diverse array of base materials including polymers, metals, ceramics, THE EMERGING ROLE OF AI IN CERAMIC ADDITIVE MANUFACTURING The integration of artificial intelligence for predictive modeling and adaptive learning allows manufacturers to achieve unprecedented levels of efficiency and precision in ceramic AM products. Bhargavi Mummareddy,* Dimensional Energy, Ithaca, New York Kalyan Immadisetty, St. Jude Children’s Research Hospital, Memphis, Tennessee *Member of ASM International rapid prototyping and customization, AM gained quick popularity. It has become indispensable across sectors including aerospace, automotive, health- care, and consumer goods, fostering innovation and efficiency in product development and manufacturing. The capability to iterate designs swiftly and reduced time-to-market has established AM as a cornerstone of and composites, AM techniques fuse materials through either binder or en- ergy application, marking a significant leap over traditional manufacturing methods. Due to the substantial advantages of AM technologies compared to traditional manufacturing methods including unmatched precision in creating intricate geometries, material waste reduction, and facilitation of Fig. 1 — Applications of ML in additive manufacturing[1]. Shown are some of the ML techniques and how they can be adopted to harness the printing process.
ADVANCED MATERIALS & PROCESSES | SEPTEMBER 2024 1 7 achieve full density and mechanical attributes. Additionally, to fully utilize the potential of ceramic AM in industry, it is crucial to fine-tune the process parameters for various materials over the span of several applications. The integration of machine learning (ML) and artificial intelligence (AI) into ceramic AM procedures is expected to play a critical role in overcoming these challenges. For example, the application of ML techniques (Fig. 1) such as statistical learning theory (SLT), support vector machines (SVMs), Bayesian modeling, neural networks, and reinforcement learning (RL) is revolutionizing manufacturing processes. These technologies are at the forefront of predictive maintenance, quality control, classification, regression analysis, and process optimization, heralding a new era of manufacturing efficiency and innovation[1]. Presently, ML and AI are enhancing efficiency, quality, and performance across several domains. contemporary product development and manufacturing strategies. EMERGENCE OF CERAMIC AM TECHNIQUES Among all the AM techniques, ceramic additive manufacturing has demonstrated the potential to overcome unique challenges posed by ceramics in traditional manufacturing, such as high melting points, brittleness, and hardness. Ceramics are renowned for their resilience under extreme conditions and find extensive application across industries including biomedical, aerospace, automobile, refractory, chemical reactors, and electrical components. However, AM harnesses these properties to fabricate intricate objects layer by layer, showcasing ceramics’ versatility in various applications. This not only underscores ceramics’ critical role in advanced manufacturing but also navigates their complexities to deliver groundbreaking solutions. Currently, a few techniques recognized by ASTM International are used for 3D printing ceramics. These include: • Binder jet 3D printing involves applying a liquid bonding agent onto a bed of ceramic powder layer by layer, cured by UV light, then followed by debinding and sintering to obtain a final component. It is suitable for larger parts, but can result in high porosity. • Stereolithography or vat photo- polymerization uses a UV laser source to cure photosensitive resin with ceramic powder suspension, layer by layer. It is ideal for producing complex geometries with fine details. • Inkjet printing is similar to binder jetting, however the major difference lies in the liquid binder with ceramic suspensions referred as ink and this ink is cured into layers using UV rays to form a component. This process offers a high precision component and is suitable for complex part building while taking longer times. • Fused filament fabrication (FFF) uses a filament loaded with ceramic material to build a structure layer by layer using heat as fusing method. This is the most affordable and fastest building technique among all the AM methods, however, FFF offers less precision compared to other options. ROLE OF MACHINE LEARNING AND ARTIFICIAL INTELLIGENCE Although ceramic AM stands at the cutting edge of manufacturing innovation, providing a sustainable and efficient means to fabricate ceramic components with unparalleled precision, its evolution is ongoing. Given that ceramic 3D printing encompasses several phases—design, printing, post- processing, and quality validation— the final output’s integrity often encounters obstacles due to the physical, mechanical, and thermal characteristics intrinsic to the materials used. These challenges necessitate exacting control throughout the design, debinding, and sintering processes to (a) (c) (b) Fig. 2 — Potential scenarios for AI application in additive manufacturing: (a) A 3D surface plot of a SiO2 3D-printed coupon. AI can analyze this data for defect identification and process optimization. (b) A PCA plot of load data versus time of 3D-printed ceramic coupons, demonstrating PCA’s use in data analysis, pattern recognition, and material classification based on performance over time. (c) Images of a lattice structure: a CAD design (left) and a printed coupon using vat photopolymerization (right). AI can compare the CAD design with the printed object to ensure accuracy, detect defects, optimize geometric design and process parameters, and control quality.
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