6
Sciences of Extreme Materials

INTRODUCTION

The mission of the U.S. Army Combat Capabilities Development Command (DEVCOM) Army Research Laboratory’s (ARL’s) sciences of extreme materials competency is to

The competency’s vision aims to

Its research areas include advanced manufacturing sciences, functional materials, high-strain-rate materials response, materials and data science, the mechanics of materials, novel synthetic molecular systems, structural and ballistic material synthesis, and processing and characterization. Underpinning these research areas, the competency strives to develop capabilities in foundational research, characterization techniques, and computer modeling.³

The competency is made up of three core competencies, which include invincible materials, invisible materials, and super materials.

The focus of the invincible materials core competency is to “mature and demonstrate advanced lightweight materials, agile manufacturing processes, modeling, and simulation and design optimization methodologies to provide survivability and durability performance improvements at acceptable weights.”⁴

The super materials core competency focuses on foundational materials and manufacturing research on ultra-high temperature materials, structural materials for munitions and missiles, gun barrel materials for all calibers, and non-energetic propellant binders.⁵

On June 4–6, 2024, the Panel on Assessment of Sciences of Extreme Materials visited the Aberdeen Proving ground in Aberdeen, Maryland. During this visit, the panel viewed podium and poster

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¹ N.S. Weingarten, 2024, “Story of the Competency Structure – Sciences of Extreme Materials,” U.S. Army Combat Capabilities Development Command (DEVCOM) Army Research Laboratory (ARL) presentation to the committee, June 4.

² Ibid.

³ Ibid.

⁴ Ibid.

⁵ Ibid.

presentations, toured facilities, and spoke to the scientific researchers within the competency. Below is the summary of its findings as they relate to the assessment criteria questions. As part of the assessment, the Army Research Laboratory Technical Assessment Board (ARLTAB) and its panels were asked by ARL to provide suggestions of specific people and organizations relevant to the work it is doing, or could be doing, that it could connect with. The fruits of this brainstorming activity are captured in the pages of the following chapter. It is important to note, however, that while certain individuals or organizations are mentioned, the ARLTAB and its panels are in no way being prescriptive about connecting to these outside entities and understand there may be other exemplars of equal value in the research community. ARL should therefore use its best judgement as to whether these ideas could be helpful.

TECHNICAL QUALITY OF THE COMPETENCY

Invincible Materials Core Competency

Achievements and Advancements

Through the “Invincible Materials Portfolio Overview” presentation, the invincible materials research thrust was described as the development and optimization (including modeling and simulation) of lightweight materials with improved survivability and durability, including in extreme (e.g., dynamic loading) and non-traditional (e.g., electromagnetic) environments.⁶ Some of these efforts were focused on creating the “invincible soldier,” better vehicle protection, and advanced manufacturing.

The quality of the research in the portfolio is on par with other leading national/international research institutions and funding agencies and the research for polymers, including two-dimensional (2D) polymers, is best in class. For this polymer research, deep subject-matter expertise has been developed by the core competency on state-of-the-art polymer design and responsiveness to stimuli (e.g., to induce mechanical response) that take advantage of novel chemistries. For 2D polymers, translational aspects are strong and viewed as an exemplar for technology maturation and integration with industry partners. An increased awareness of research within the polymer industry may be beneficial to the ARL, and its work may be strengthened by ongoing and new strategic partnerships (as discussed further in the next section on “Research Portfolio Opportunities”).

Additionally, work on armor and composites and their integration into systems for the soldier and vehicle protection is best in class and remains distinct across the Department of Defense (DoD). Furthermore, capabilities and subject-matter expertise in powder processing of metals and ceramics (e.g., including new cold spray capabilities) and the ability to produce complex shapes is unique to ARL and across DoD.

Regarding modeling and simulation, examples like steel design and composites were highlighted. The proper methods and tools are being developed and used, and there is strong emphasis on artificial intelligence (AI) and machine learning (ML). Suggestions on how to expand this toolset are discussed in the next section.

The ARL extramural projects portfolio is impressive and covers a wide spectrum of research, including polymer chemistry, materials science, mechanics, and computational science. Understanding the dynamic response of novel materials in extreme, complex environments in the presence of coupled mechanical, electromagnetic, and thermal loads and the development of models to predict such behavior remains a challenge that this portfolio is uniquely positioned to tackle.

Several projects highlighted in the Army Research Office (ARO) “Invincible Materials” presentation also reflect the breadth of the extramural portfolio. These projects are related to unique materials architecture, granular crystals (traditionally known as particulate materials) and their

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⁶ K. Behler and R. Lambeth, 2024, “Invincible Materials Portfolio Overview,” DEVCOM ARL presentation to the committee, June 4.

mechanical responses to quasistatic loads, damage mechanics in woven composites under dynamic loads, as well as inhomogeneities and defects. A strong emphasis on modeling and computational approaches is a signature of this portfolio, and the research methods employed in the presented projects are sound. This presentation and portfolio demonstrated a broad understanding of the underlying materials science and mechanics being conducted in the field at large. The list of external investigators is extensive and includes many well established, senior academics and assistant professors from leading R1 universities.

Key entities in the core competency portfolio include mechanisms like cooperative agreements (CAs) and cooperative research and development agreements with universities and industrial partners; the National Science Foundation’s (NSF’s) Designing Materials to Revolutionize and Engineer Our Future (DMREF) and DoD Multidisciplinary University Research Initiative (MURI) partnerships with academia; coordination with DEVCOM centers as well as with the Air Force, Navy, and other Army agencies. Important Army-related activities engaged in by the core competency include leading the materials thrust for the enabled soldier and developing efforts to revise military details (MIL-DTLs) and performance specifications (PRFs).

Some highlighted partnerships found across the core competency and broader competency portfolio include Carnegie Mellon University; Cornell University; Duke University; Georgia Institute of Technology; University of Arizona; University of California, Berkeley; University of California, San Diego; University of Chicago; University of Michigan; and University of Wisconsin, just to name a few. These interactions, which are supported by CAs, MURIs, etc., have resulted in numerous, peer-reviewed journal publications in top journals like Science and Materials and Design. Partnerships and collaborations with industry have also been realized for 2D polymers and metallic alloys. These efforts have resulted in the knowledge, skills, and capabilities needed to meet the core competency’s goals—including the development of invincible materials and demonstrations that consider size, weight, power, and cost trade-offs to achieve enhanced performance and survivability.

Research Portfolio Opportunities

While the extramural invincible materials core competency presentations showed a strong portfolio of work, opportunities exist to improve direction and add projects focused on novel materials and their response to complex loading conditions that include mechanical, electromagnetic, and thermal loads. Many of the presented projects focus on mechanical response, whereas the overall goal of the invincible materials core competency portfolio includes a wide range of non-traditional environments and electromagnetic spectrum. Given the strong computational mechanics emphasis of this portfolio, there is an opportunity to build connections with other ARL research thrusts/directions. Materials processing under extreme mechanical, thermal, and electromagnetic conditions would be a natural fit to investigate the effects of extreme fields and their interactions on materials response, damage, and failure. The competency portfolio may also consider expanding its efforts to study materials in extremes to further include other (thermal, electromagnetic, etc.) environments and coupled environmental responses.

While research being pursued by the ARL represents the state of the art for advanced materials like high-entropy alloys (HEAs) and basic (6.1) extramural collaborations with universities and industry are appropriate and strong in many instances, as exemplified for 2D polymers, coordination with other federal and academic partners is encouraged to facilitate knowledge sharing and enable the ARL to establish distinct scientific priorities that avoid overlap with other efforts in the field and promote scientific leveraging. For example, significant efforts are being sponsored by DoD entities like the Air Force Research Laboratory (AFRL) and the Office of Naval Research (ONR), the National Aeronautics and Space Administration (NASA), and the Department of Energy’s National Nuclear Security Administration (NNSA) in high-throughput materials discovery, synthesis and processing, and testing (e.g., high-strain-rate testing) of metals and alloys in extreme environments. Connecting to these efforts may afford significant opportunities for leveraging research, establishing future collaborations, and avoiding duplicative efforts. This will help to ensure that ARL’s scientific priorities are differentiated from other efforts across DoD. This core competency can also enhance its connections to industry, which

will benefit several projects, including Resins with Adaptive and Reversible Properties, 2D Polymers: High Performance Films for Soft Armor and Optical Control, and Polymer Networks. Additional suggestions for ARL connections with industrial, DoD, and academic entities are provided in the “Opportunities Identified for Individual Projects” section below. In addition, if the core competency is not already doing so, it can connect with the biosynthesis and biomaterials core competency to determine potential collaborative efforts on polymer research.

Furthermore, while theory, modeling and simulation, analysis, and experimentation are sound and integrated across the invincible materials core competency portfolio, opportunities exist to strengthen physics-based modeling and simulation, especially microstructure-driven approaches, to enhance ongoing AI/ML efforts. ARL could consider prioritizing verification and validation (V&V) and uncertainty quantification (UQ) as they may help to inform and streamline future efforts, including experimental ones.

Finally, in considering the request for commentary on where research may be at a risk of not meeting its objectives, it should be noted that while the extramural portfolio is very broad (polymer chemistry, particulate materials, mechanics, etc.), the majority of the highlighted projects focused on quasistatic experiments. Although this is important, it may be insufficient to meet the core competency scientific objectives. A focus on dynamic behavior of relevant materials systems will also need to be maintained. It is, however, understood that the projects shown during the review may not represent the entire ARL portfolio and that new acquisitions may be in process; however, these points are mentioned in case more attention needs to be paid in this direction.

Invisible Materials Core Competency

Achievements and Advancements

The invisible materials core competency portfolio encompasses multiple extramural and intramural projects that collectively aim to reduce the visibility of objects, often across a broad spectral range, and to add a dynamic dimension to such spectral manipulation. The core competency has a wide-ranging vision to understand and leverage control of material structure, shape, and properties. On the properties side, these include color- and texture-changing materials and materials with controlled thermal properties. On the synthesis and structure side, these include three-dimensional (3D) self-assembled metamaterials and interfacial reactions in functional hybrid materials.

The core competency has achieved noteworthy successes. Some of these success center around understanding how pigments and structure color work as camouflage in cephalopods and achieving relatively high thermal conductivity in 3D printed composites. Extramural research is largely performed by U.S. academia, with some involvement from international academia. This part of the program aims to advance materials design, polymer chemistry, surface and interface chemistry, as well as adaptive self-assembly of materials, addressing the following research areas within the competency: electro-optical (EO) and infrared materials, thermal materials, and autonomy.

The extramural efforts are robust and productive. These extramural collaborations have already yielded multiple presentations and peer-reviewed publications in high-quality respected journals, such as Science, Nature Communications, and Advanced Materials, with a few notable results that include self-healing polymer films, cephalopod-inspired dynamic structured color, and adaptive self-assembled materials. These efforts—performed by leading faculty at major academic institutions—are state of the art. They are resulting in peer-reviewed publications in national and international journals. Here, the extramural portfolio leads the way of scientific research and innovation, on par with other major DoD and non-DoD funding agencies.

Intramural researchers have also achieved a great deal of success with their projects, and these successes, along with some identified opportunities, are discussed in more detail in the section on “Opportunities Identified for Individual Projects” below. It is noteworthy that ARL intramural researchers collaborate with extramural researchers. For example, two intramural scientists collaborate

with researchers at the University of Pennsylvania and Northeastern University on a cephalopod-inspired pigment project called Cephalopod-Inspired Pigments and Color-Changing Materials.

Both intramural and extramural researchers within the core competency demonstrated they have a broad understanding of underlying science and research conducted elsewhere. As mentioned, extramural projects often aim to disseminate their results via open peer-reviewed academic publications. The rigorous peer-review process inherently ensures that research efforts are not done in isolation, and that the new science is reflective of research conducted elsewhere. Interaction with intramural scientists at ARL made it clear that these researchers understand the state of the art within the broader scientific community and can readily identify contributions of their research projects. Additionally, the projects demonstrate deep understanding of the underlying science, both in theoretical and experimental efforts. Some projects demonstrated emerging ML acceleration of research efforts. That said, some suggestions on how to better integrate theory and experimental efforts, especially in early-stage projects, are provided in the next section below.

Both extramural and intramural researchers are using sound research methods and methodologies. The peer-review process also ensures the extramural researchers are using adequate methodologies when designing their studies, as well as in data analysis, and there are no concerns in this regard for extramural researchers. The methods and methodologies used in the intramural work, which does not always show up in open peer-reviewed research, similarly, have been reasonably thought out. The interaction with ARL researchers during the review demonstrated the researchers’ grasp of the methodologies at their disposal, and careful reasoning for selecting the particular methods for the particular project.

The assessment criteria asked for commentary on the overall balance of the competency’s research portfolio (e.g., core competencies, partnerships, supporting extramural partners) to address the cumulative competency goals. The projects described represent a good balance of extramural/intramural research and there are no concerns in this regard. In addition, the PSQs supporting the core competency are good questions.

Research Portfolio Opportunities

The assessment criteria asked for commentary on opportunities, if found, within the competency where improved direction, increased focus, connections with other research lines, or other changes could better and more quickly address the competency objectives. Presentations and posters shown during the review demonstrated scientific expertise across multiple areas of science and technology, including materials science, spectroscopy, imaging, and chemistry, among others. In the portfolio of invisible materials, several researchers are working on engineered electromagnetic materials and, separately, on engineering thermal and phononic flows within materials. Closer communication between these groups of researchers may open up new scientific avenues, since the equations describing transport of elastic and electromagnetic waves are similar.

While there are no risks identified at the core competency level, the Bio-Based Fibers for Camouflage project seems to be at an initial stage and would benefit from more detailed analysis of the parameter space, in part to be able to narrow down the list of important parameters in the future. For example, the researchers may record not just the type of the fiber, but also its weave. Diffuse transmittance spectroscopy and its diffuse reflection counterparts⁷ may be useful in characterization efforts.

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⁷ See, for example, A. Taboudoucht and H. Ishida, 1989, “Diffuse Transmittance Spectroscopy of Polymeric Fibers,” Applied Spectroscopy 43:1016.

Super Materials Core Competency

Achievements and Advancements

The objective of the super materials core competency is to increase the range, lethality, structural, and thermal integrity of materials through materials science and manufacturing. The ARL scientists are excellent, and the facilities are world class. It is evident that clear leadership is being provided to this core competency both intra- and extramurally, and the managers are well attuned and sensitive to the scientific goals of the core competency.

The topics presented in the super materials core competency align well with the PSQs that have been outlined by the super materials program, and all the researchers are using state-of-the-art methodologies, fabrication facilities, and analysis tools. The experimentalists and the modeling/simulation personnel within the core competency are interacting and exchanging insights and overviews.

The core competency’s research is on par with other leading research institutions nationally and internationally. Still, more strongly establishing their knowledge of the state of the art in their presentations and written documents (perhaps through a slide devoted to their knowledge of state-of-the-art research) could help to demonstrate their understanding of research done elsewhere, as an understanding of outside research was not always apparent.

Research Portfolio Opportunities

While the core competency is using state-of-the-art research methods and methodologies, there are identified opportunities for further augmentation, including the following:

• Simulation is a very useful tool in obtaining molecular-level information in carbon materials, although it should be mentioned that since simulations can only capture nanoseconds, enhanced sampling methods can be used to accelerate the kinetics. In reference to the polybenzoxazine-derived carbon structure simulation presented during the review, incorporating more polymerization pathways into simulations to mimic the experiments would be useful. This would help in capturing the processing–structure–property relationship through the simulations as well.
• Work focused on C/C composites has a good experimental (chemist) approach, however, simulations are conducted separately. The connection between the experimental and simulation work could be further improved to gain more fundamental insights. One way to do this would be to use data science or ML to exploit the data from both sides.

Additionally, further attention to model and analyze uncertainty could benefit the overall research effort. This broadly refers to the application of statistical approaches to guide the analyses.

Furthermore, continued communication with other DoD laboratories and other experts (industry, academia) in the field could also help the researcher stay connected to scientific advances in their areas. A more in-depth understanding can greatly focus research efforts as the community builds on the knowledge of others. Knowledge of current and previous work keeps the research moving forward, limits the organization from becoming insulated from outside activities, and can generate new research ideas and direction. This chapter provides helpful references in line with these suggestions.

The assessment criteria also ask for commentary on opportunities, if found, within the competency where improved direction, increased focus, connections with other research lines, or other changes could better and more quickly address the competency objectives. The criteria also ask for novel research approaches that the competency should consider pursuing. Some general comments focused on these two questions are provided below.

• Projects focused on manufacturing and processing science are rich in data (during and after manufacturing). Exploiting more data science-based approaches could get fundamental scientific insights that connect processing-structure relationships and potentially accelerate the manufacturing process by pin-pointing the limiting process.
• It is understood that most of the manufacturing work for ARL is provided by external collaborators. However, knowledge of smart manufacturing processes and additive manufacturing capabilities, and limitations, could help broaden the range of material possibilities. This will also help to guide researchers to assess the feasibility of materials from the fabrication perspective. The investigation and application of smart manufacturing techniques is also encouraged. ARL could also consider connecting to various programs on AI/ML (e.g., AFRL and NASA) for the additive manufacturing of metals.
• Another opportunity for the laboratory to grow would be adding researchers working at the interface of ML and materials science. This would be specifically important to (1) develop models that are grounded in the fundamentals of material science and (2) help in extracting scientific insights from physics or chemistry-based ML models that can aid in improving processing and/or achieving desired properties.
• There is an opportunity to connect the ARL research areas more precisely with the broader processing science of other academic and government laboratories. This can be accomplished in several ways, including an in-depth literature understanding of the state of the art, interactions with other laboratories via visits, tech committee involvement, and conference attendance (this is discussed below in greater detail).
• Microstructure-driven approaches could be added by utilizing AI and data from other models to determine preferred microstructures to achieve desired properties for a specific material of interest (e.g., ultrahigh temperature ceramics, C/C composites). This knowledge could be applied to guide the processing procedures that will achieve desired microstructures.

The assessment criteria also asked for comment on any specific areas, if found, where the research may be at major risk of not meeting its objectives and provide reasoning. While there are no major risks at the competency level, for the research not meeting its objectives, the technical presentations did not include critical timelines or deliverables, and so there was no sense of the “go/no go” in the work. This is not a criticism, as most 6.1 and 6.2 research does not have strong timelines, however, it would be helpful to know (1) What are the key performance indicators? and (2) What constitutes success or failure? To help guide and motivate the researchers, it is suggested that milestones be added to direct the research and be provided in future presentations of this work.

In viewing the super materials core competency portfolio holistically, a few observations emerged:

• ARL may want to consider more closely connecting the three areas it states as overarching research goals (range, lethality, and structural and thermal integrity) with its individual intramural research efforts.
• ARL’s sciences of extreme materials competency has a very talented technical staff that are clearly passionate about their work. The Rodman laboratory facilities are world class with capabilities that are unique in the United States. The combination of excellent technical staff and facilities affords ARL the opportunity to lead programs and address problems unique to Army sciences that cannot be addressed by other researchers. Thus, ARL may be missing an opportunity to solidify its brand and the extent of its technical achievements amongst non-academic laboratories. In line with this point, an important question emerges, How can ARL increase its technical presence in the non-academic laboratory space? Some suggestions on how to answer this are summarized below.
  1. More Intentional Promotion of ARL’s Laboratory Facilities, Equipment, and

• 1. Capabilities. Industry and academic partners could benefit from use of the Rodman laboratory facilities, providing ARL with unique opportunities to collaborate with a broader spectrum of the technical community and be more widely known for its technical achievements. While it is understood that issues of security cause ARL to limit who can come into their intramural laboratories, ARL may be able to find a way to safely foster greater collaborations at the Aberdeen Proving Ground.
  2. Conference Participation/Presentations. During the review, it was learned that the administrative and approval process for attending conferences was onerous. For high-profile conferences (e.g., Gorden Research Conferences [GRCs]), attendance can be limited and may work on a first-come, first-serve basis. It is therefore important that ARL administrative processes are streamlined to ensure rapid review and approval of conference attendance applications. More external visibility of the technical achievements of the super materials core competency staff presented broadly will help to publicize the ARL name, as well as the top-notch laboratory capabilities that allow for unique experiments. Conference presence and presentations can also instigate new collaborations and help keep ARL staff abreast of the state of the art—which could yield more high-risk/high-reward projects, and projects at the cutting edge. This also provides a potential mechanism for external peer review. ARL needs to consider finding ways to reduce barriers to conference attendance, especially for early-career personnel. Some relevant conferences include the following: American Ceramic Society (ACerS) Annual Conference; ACerS International Conference and Expo on Advanced Ceramics and Composites; TMS (The Minerals, Metals & Materials Society) Annual Meeting and Exhibition; International Conference on Composite Materials; SAMPE (Society for the Advancement of Material and Process Engineering) Conference and Exhibition; GRC; and, DYMAT (European research association in the field of Dynamic Behavior of Materials).
  3. External Networking (Participation in Technical Societies and Committees). Having early-career scientists and engineers more involved with the planning and execution of technical conference/workshop programming will contribute to their technical and professional development, provide more research visibility, and further mature the ARL brand. Identification of mid- to late-career ARL technical professionals would be helpful toward initiating or encouraging connections in their research areas with technical committees, organizers of technical conferences and workshops. This has been effective with ARL staff members attending the Society for Experimental Mechanics annual conference focused on extreme materials science, as junior colleagues have become involved in jointly planning future conference sessions and/or contributing to technical committees.
  4. Internal Networking. There was a sense of siloing amongst research occurring at ARL. This happens in many organizations, due to the specific focus of the staff and programs. Being intentional with gathering technical professionals to share research successes and challenges would be beneficial. New ideas and collaborations are often generated from such cross-pollination. Having key members of the technical staff, and leadership prioritizing such opportunities, will be important. The creation of a research forum or internal seminar series is suggested with possible incentives for attendance.
  5. New Extramural Partners. The desire to continue collaborations with the same extramural partners is understandable. Working with researchers whose work is known provides a beneficial and productive exchange. However, there are benefits to bringing in new people with innovative ideas and approaches into ARL research. Expanding the range of academic collaborators will also provide a means of informing them on ARL’s excellent staff, capabilities, and facilities.

Finally, a related note that ties in with ARL’s ability to connect with the scientific community is how such connections may inspire high-risk/high-reward intramural projects through closer acquaintance with emerging scientific advances. The intramural research and the research presentations often followed a traditional approach to research with a shorter-term (<5 years) vision. For example, it was observed that in one case (i.e., C/C composites research) cutting-edge tools were used, but through low-risk approaches. Although this type of research is necessary, the intramural researchers may consider taking the lead in new research areas that are less explored by the existing technical community (academic, DoD laboratories, etc.) who work in these areas. Specifically, part (not all) of the portfolio could explore high-risk/high-reward concepts or ideas. This would help them to explore more cutting-edge technologies and fully exploit the capabilities of their cutting edge-tools, as well as the talents of their technical staff. Related questions may be about what new ideas are being explored that could establish research areas where the core competency team can take the lead. The competency has the technical talent to think outside of the box. Thinking bigger and attacking bigger, long-term problems, and exploring revolutionary (versus evolutionary) technologies in the intramural 6.1 efforts is encouraged.

Opportunities Identified for Individual Projects:

The following opportunities were identified for an individual project that was presented during the review:

• Resin Chemistry and Graphizability—The following list of leaders in benzoxazine chemistry and its applications in countries friendly to the United States (listed in alphabetical order) may be helpful for the team to reach out to:
  1. Professor Thanyalak Chaisuwan, Petroleum and Petrochemical College, Chulalongkorn University, Thailand
  2. Professor Suwabun Chirachanchai, Petroleum and Petrochemical College, Chulalongkorn University, Thailand
  3. Professor Philippe Dubois, University of Mons, Belgium
  4. Professor Pablo Froimowicz, Department of Macromolecular Science and Engineering, Case Western Reserve University
  5. Professor Ian Hamerton, Composite Institute, University of Bristol, United Kingdom
  6. Professor Baris Kiskan, Department of Chemistry, Istanbul University of Technology, Turkey
  7. Professor Katharina Koschek, Department of Polymeric Materials and Mechanical Engineering, Fraunhofer-Institut für Fertigungstechnik und Angewandte Materialforschung (IFAM), Germany
  8. Professor Shao-Wei Kuo, Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Taiwan
  9. Professor Bimlesh Lochab, Department of Chemistry, Shiv Nadar University, India
  10. Professor Pierre Verge, Department of Materials Research and Technology, Luxembourg Institute of Science and Technology, Luxembourg

PORTFOLIO OF SCIENTIFIC EXPERTISE

Invincible Materials Core Competency

The teams of intramural and extramural scientists and engineers involved in research supporting the invincible materials core competency portfolio contain subject-matter experts in their respective fields

who are well qualified to perform the work. In particular, the portfolio of scientific expertise of extramural scientists is impressive and diverse. The core competency teams are active in their communities and have produced scientific outputs such as peer-reviewed journal publications and have been invited to speak at national/international conferences. The culture at ARL appears to be collegial, especially at the peer-to-peer level.

ARL could seek out further engagement opportunities across DoD with AFRL or perhaps with universities supported by ONR to expand its network in topical areas of interest, further define distinct ARL scientific priorities, and amplify ARL’s research outputs. Opportunities for scientists and engineers to become more involved in professional societies and to attend national and international conferences are also encouraged.

Suggestions for ARL to enhance or grow its portfolio of scientific expertise include increasing opportunities for their scientists and engineers, especially early career, to attend national and international conferences. Relevant conferences include the TMS Annual Meeting and Exhibition, the Materials Science and Technology (MS&T) Technical Meeting and Exhibition, American Physical Society meetings, Materials Research Society (MRS) meetings, American Society for Composites Annual Technical Conferences, and specialty conferences. Additionally, ARL may encourage, where appropriate, more articles in peer-reviewed journals to grow the reputations of its scientists and that of ARL nationally and internationally. Possible peer-reviewed journals include, for example, Metallurgical and Materials Transactions A, Materials Science and Engineering A, Materials & Design, Scripta Materialia, Acta Materialia, Science, Nature Materials, Nature, Composites Science and Technology, and Composites Part A: Applied Science and Manufacturing. ARL may also consider diversifying its extramural collaborations to grow its university network and expand its potential hiring pipeline. This may be accomplished by leveraging other AFRL, ONR, DOE/NNSA, and/or NSF-supported academic efforts and centers, as noted above.

Invisible Materials Core Competency

Based on the interactions with researchers during the review, the invisible materials core competency team is highly qualified to perform state-of-the-art research. The efforts of ARL researchers in presenting and disseminating their results at high-profile conferences such as the American Chemical Society, SPIE, and MRS are to be applauded. Continued participation and attendance of ARL researchers in addition to university collaborators is encouraged. In order to retain expertise and better address emergent trends and challenges, researchers will need to interact with broader scientific communities. Regular presentations by ARL researchers at national or international conferences or, at least, regular attendance at such conferences is important. The conferences that are relevant to the invisible materials portfolio include those of the MRS, the Conference on Lasers and Electro-Optics (CLEO) conferences for visible/infrared materials, and a large number of topical meetings that are often co-organized by Optica, SPIE, and IEEE.

Super Materials Core Competency

Overall, the teams supporting the super materials competency are strong, impressive, and clearly passionate about the work they are performing and their contributions. The presenter of the ARO Super Materials presentation evinced strong interim leadership and was deeply engaged with the Synthesis and Processing Program, working well with the funded grants from the former program manager. The laboratory tours allowed further interaction with the staff, who were universally impressive. As previously mentioned, another opportunity for the laboratory would be through the addition of researchers working at the interface of ML and material science. This expertise would be specifically important for developing models that are grounded in the fundamentals of material science and to help in extracting scientific insights from physics- or chemistry-based ML models that can aid in improving processing

and/or desired properties. Projects focused on manufacturing and processing science are rich in data (during and after manufacturing). There may also be benefits to having a dedicated polymer chemist in the super materials core competency team, as many of the current problems lie in this research domain. The addition of one or more ceramists, or high-temperature materials experts, would also benefit the research efforts in ceramic processing and C/C composites.

The way ARL communicated its presentations throughout the competency (and across the three core competencies) was very good, and the poster session provided additional perspective and the opportunity to interact with principal investigators. The presentation slides were well-prepared and easy to read and follow. Still, the junior staff could benefit from being mentored in presentation skills and presentation practice. Guidance from skilled senior staff will aid with presentation skills to help junior presenters rely less on written notes. Such skills are transferable and will be important for these researchers to communicate their research to different audiences in the future. More guidance and encouragement from senior staff on how to become more involved in the ARL technical community (outside of their focus areas) and beyond (e.g., technical and professional societies and committees) will also reap benefits. This would be an effective way to expand the ARL brand, and researchers’ personal brand and build a better scientific network.

FACILITIES AND RESOURCES

Invincible Materials Core Competency

The facilities and personnel supporting the ongoing intramural and extramural research in the invincible materials core competency portfolio are top notch, especially as they relate to polymer processing.

The staff expertise matches well to the facilities and resources, which ensures proper utilization of these facilities. ARL will need to prioritize support for preventative and continued maintenance to keep its capabilities and facilities world class and maintain existing capabilities.

The 6.1 2D Polymers project had collaborations that are highly appropriate for chemistry sourcing and for scaleup. (See previous comments about more broadly leveraging large company chemistry and processing expertise.) The 6.1 presentation “Resins with Adaptive and Reversible Properties” and the “Polymer Networks” poster all had facilities that seemed to be highly appropriate for the work that was being performed. The 6.1 “Dynamic Failure of Metals” poster also had staff expertise that matched well to the facilities and resources available for dynamic testing of metals and alloys and has the knowledge necessary to assess the microstructural and mechanical performance of 5xxx series Al alloys.

In addition, the 6.1 ARO Invincible Materials focus, the 6.2 Next Generation Thermoplastic Composites project, the 6.2 “Lightweight Composites” poster, the 6.1 “Cemented Ceramics: Liquid Silicon Infiltration of Composites” poster, and the 6.1 “Dynamic Response of Hybrid Composites for Hard/Soft Armors” poster all had a strong synergy of staff expertise that matched well to their facilities and resources. For the 6.1 “Alloys for Protection” poster, the staff also had expertise well matched to the facilities and resources, especially with respect to dynamic testing of materials for protective structures.

Invisible Materials Core Competency

ARL has truly unique facilities, including experimental capabilities that can be of interest to researchers from outside the ARL. Several of these are not available in universities or in other research laboratories. Should access to these facilities be available to wider research and technology communities, it would open new areas for collaboration between ARL and the wider community and will likely instigate further research. It is understood, however, that limitations owed to maintaining a secure environment may present obstacles to inviting broader research communities into ARL.

Super Materials Core Competency

The facilities at ARL supporting the super materials core competency and the sciences of extreme materials competency as a whole are exceptional and world class. The processing facilities included hot presses and autoclaves as well as thermoplastic extruders. All of the equipment was of large enough scale to conduct research that goes beyond, and differs from, what those found in average academic institutions can do. This is a great strength of the ARL. Metals processing also seems strong. Investing resources to help maintain the facilities is encouraged.

THEMES THAT CUT ACROSS COMPETENCIES

It was found that in all core competencies, conference attendance and participation could be enhanced and prioritized. Example conferences that can support the invincible materials core competency include the TMS Annual Meeting and Exhibition, the MS&T Technical Meeting and Exhibition, APS meetings, MRS meetings, American Society for Composites Annual Technical Conferences, and specialty conferences. Conferences that are relevant to the invisible materials portfolio include the MRS, CLEO conferences for visible/infrared materials, and a large number of topical meetings, which are often co-organized by Optica, SPIE, and IEEE. Conferences that are relevant to the super materials core competency include the ACerS Annual Conference; ACerS International Conference and Expo on Advanced Ceramics and Composites; TMS Annual Meeting and Exhibition; International Conference on Composite Materials; SAMPE Conference and Exhibition; GRC; and the DYMAT.

A focus on AI/ML could be increased in certain areas of the competency as identified in this chapter (e.g., ARL could consider connecting to various programs on AI/ML [e.g., AFRL and NASA] for the additive manufacturing of metals in the invincible materials core competency and adding the expertise of someone who can work at the interface of ML and data science for the supermaterials core competency). Additionally, V&V and UQ approaches and physics-based modeling and simulation need to be prioritized to enhance AI and ML efforts that are taking place within the invincible materials core competency and super materials core competency portfolios. These techniques could benefit multiple current and future projects.