5

Materials Science and Engineering

INTRODUCTION

The Materials Science and Engineering Division (MSED) supports the NIST Material Measurement Laboratory (MML) activities in advanced manufacturing (including Materials Genome Initiative 2.0, Additive Manufacturing and Biomanufacturing) and in Quantum Materials with the Physical Measurement Laboratory. The division also has programs in nano lithography, sustainability, and dental materials. Many of the topics are crosscutting between programs, and some programs are shared with other divisions of NIST. MSED made six presentations to the panel, including the following: Thermodynamics and Kinetics Group, the Mechanical Performance Group, Polymers and Complex Fluids Group, Functional Polymers Group, Polymers Processing Group, and the Functional Nanostructured Materials Group.

In MSED, there are a total of 151 staff members, which includes permanent staff, postdoctoral fellows, associates, and administrative support. In 2017, the staff was 168, indicating the total staff count has decreased by 17 persons over the past 3 years. Most of the reductions in staff are in the category of associate postdocs, which went from 44 to 27 during the past 3 years. (Associate postdocs are funded not by NIST but by another sponsoring organization.) MSED staff represents about 19 percent of the total MML staff. The budget for 2020 was $27.457 million, which included indirect cost.¹ The budget is essentially flat as compared to 2017 when the panel last reviewed the laboratory.²

ASSESSMENT OF TECHNICAL PROGRAMS

Accomplishments

MSED’s Thermodynamics and Kinetics Group is respected world-wide for its expertise in computational materials science. Its primary goal is to reduce the cost and time of alloy development. In addition to staff expertise with computational tools (e.g., CALPHAD, etc.), its suite of data repositories (e.g. phase-based data center, interatomic potentials repository) are becoming highly valued in the academic and industrial research communities.

Good models without solid empirical validation and downstream applications have limited value. Therefore, the group has empirical laboratory facilities to cast and process metal alloys. As additive manufacturing and other far-from-equilibrium processes become more commonplace, it will be important to strategically evaluate and upgrade laboratory equipment to keep a balance between the synergistic

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¹ Mark R. VanLandingham and John E. Bonevich, National Institute of Standards and Technology (NIST), 2020, “Materials Science and Engineering Division,” presentation to the panel, September 9.

² National Academies of Sciences, Engineering, and Medicine, 2017, An Assessment of the National Institute of Standards and Technology Material Measurement Laboratory: Fiscal Year 2017, Washington, DC: The National Academies Press.

computational and empirical approaches. One example is adding a high-temperature, gas-cooled vacuum furnace to improve non-equilibrium capability. The group has a very solid track record of metallurgical alloy development, such as in Ni and Co superalloys, and coinage alloys. Of note is its recent work on 17-4 stainless in additive manufacturing. 17-4 is a very common, higher-strength, martensitic stainless steel that has wide application nationally. However, when it is processed far from equilibrium by using additive manufacturing techniques, 17-4 stainless has dramatically different microstructure and resulting properties compared to traditionally processed material. The group is working on the alloy design of this material to provide more stable microstructure and properties when it is used in additive manufacturing. This far-from-equilibrium work is evidence of the group’s understanding and supporting new metallurgical engineering directions in this field. The group is also supporting computational polymers research, which is commendable. This is very complementary to the work in metals and will likely benefit longer-term research in industrially important processes where metals and polymers interact, such as paints and coatings.

FINDING: The computational work of the Thermodynamics and Kinetics Group is well ahead of many other entities outside of NIST.

RECOMMENDATION 5-1: The Materials Science and Engineering Division (MSED) should consider investment in additional high-performance computing resources to continue the comparative advantage the Thermodynamics and Kinetics group holds. In making such investments, MSED should maintain balance with empirical approaches.

The Polymers and Complex Fluids Group spans a wide range of scientific technologies and applications. A key to the success of this group is having and developing new analytical techniques to understand and analyze materials. In support of this, eight pieces of analytical equipment have been acquired since 2017. Such excellent equipment is one part of the equation, but also needed are dedicated users who receive cross-training to continue to excel in their application on a long-term basis. To this end, it will be important to support the integrated polymer analytics cross-functional group project in 2021. Understanding macromolecular architectures and polymer degradation mechanisms and their quantification are a strength of the group’s work in this area. The group also works hard on using polymer science in supporting other areas of technology, such as their exceptional carbon nanotube separation technology. The group overtly makes a substantial effort to identify the overlap between fundamental science and industrial need and to plan strategically based on this information. Labor, budget, and priorities are set on an annual basis.

Within the Mechanical Performance Group, the NIST Center for Automotive Lightweighting addresses a significant national need. The U.S. transportation sector consumes more energy and generates more carbon dioxide (CO₂) than buildings or industry, the other energy end-use categories. For personal transportation, lightweighting offers a direct path to meaningful energy savings and CO₂ reduction in the short-term (next 5 years) and potentially long-term. One of the immediate impacts has been in assessing sheet metal forming. This program, and associated consortia, specializes in multi-axial, multi-strain path, and high-strain-rate measurement and testing that is traditionally more difficult for individual companies to perform and model in a standardized manner. Two new approaches to cruciform testing using built-up specimens and thick-to-thin samples to better localize deformation have particular utility for automotive sheet designs and subsequent lightweighting. Measurement of macro and micro stress and high-speed thermographic measurements when performing tests is among the best in the world and brings a scientific level of insight to these mechanical testing methodologies. Digital Image Correlation (DIC) using both speckle and patterning provides empirical data to validate computational forming models. The program is to be commended for the 2020 Numisheet benchmarking study³ and its structured links to industry that

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³ NIST, 2020, “2020 Numisheet Benchmark Study Uniaxial Tensile Tests Summary,” April 29, https://www.nist.gov/publications/2020-numisheet-benchmark-study-uniaxial-tensile-tests-summary.

enable rapid dissemination of its work product into the marketplace. In the area of composites, studying fiber fragmentation with Dow and Ford is an enabler of cost-effective, high strength-to-weight ratio composite adoption in automotive and light truck applications. It should be noted that having local machine shop capability to expedite test method development is a best practice and increases efficiency in this area.

Measurement of hardness and coating thickness is essential to many products that are widely used in the economy (e.g., engine components, bearings). The National Metrology Institute capacity of MML works with numerous influential companies to assure that standards and test methods (e.g., Knoop and Vickers) are accurately and properly transitioned into the marketplace. The importance of this work to the economy cannot be understated.

Additive manufacturing is a hot topic in the field of materials science and engineering. Almost every governmental laboratory in the nation has some activity in this area. It is critical to differentiate the work being conducted at NIST, as compared to many of these other laboratories and industry. NIST is “laser-focused” on obtaining numerous, physics-based, quantitative, in situ measurements of what is happening in the “weld” pool. This is absolutely essential for several reasons, and the depth of this undertaking is what sets NIST apart from other organizations. The first reason that this work is essential is that accurate in situ measurements enable active process feedback and closed-loop machine control for reproducible and superior part quality. Second, these measurements also enable the next generation of manufacturing and data analytics to occur in this field (industry 4.0 approach). Third, it provides quantitative, accurate numerical data that can be both integrated into computational modeling efforts and used to validate computational models. Finally, these measurements provide a much deeper understanding of the physics of the additive manufacturing process, which will enable both more statistically reliable parts (and increased applications) and future technical process advancement in this area. Additive manufacturing is transitioning from a “let’s just set our process controls and see what we get after the fact” approach to a “thoughtful, modeled, physics-based, quantitative in situ measurement and closed-loop feedback control” approach. The MML is providing leadership in this effort, and its own program is among the best in the world. The MML is also to be commended for their efforts in AM Bench and One NIST, which unites the technical community and starts solid data stewardship in the field of additive manufacturing.

The Functional Polymers Group works in three areas—Polymer Transport, Polymer Matrix Composites, and Polymer Mechanics. In alignment with the overall mission of NIST, industry is the group’s number one customer, but they also interact with government agencies. Recently, the group filed six patent disclosures, four patent applications, and has three active CRADAs (Cooperative Research and Development Agreements). The majority of this work on the innovation continuum starts at lower technology readiness levels (TRLs)⁴ where they continue the efforts of academics and continue through higher TRLs up to the point that they enable commercial products (e.g., football helmet energy mitigation products, membrane technology, ballistic mitigation products). This range of TRL efforts appropriately keeps them balanced on both the science of polymers and the engineering applications that benefit the economy. This group is to be commended for thoughtfully and actively managing this balance between science and engineering. Of particular note is its work starting at the molecular level of understanding for enabling high strain rate and short-time-scale mechanics applications (e.g., impact mitigation, noise mitigation).

Work on polymer matrix composites tends to be focused on fiber–matrix and filler–matrix interactions, which are essential for high strength-to-weight-ratio applications in real-world environmental applications. Analytical techniques and the associated equipment to perform measurements

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⁴ A number of agencies maintain their own TRL scale as a measure of the maturity of technology as it progresses toward deployment. The TRL metric developed by NASA is often cited; see NASA, “Technology Readiness Level,” updated October 28, 2012, https://www.nasa.gov/directorates/heo/scan/engineering/technology/txt_accordion1.html.

at a molecular and sub-molecular level are essential to advancements in this area. Thoughtful, strategically aligned equipment renewal plans are in place to assure this continued capability.

The Functional Polymers Group is to be commended for its strategic planning and identification of targeted growth directions in the following five areas:

• Molecules as Measurements,
• Composites for Infrastructure,
• Advanced Dental Composites,
• Advanced Chemical Separations in the Circular Economy, and
• Impact Behavior and Mechanics.

These areas are in alignment with the mission of NIST and many industrial corporate strategies.

The Polymers Processing Group is unique in that they have the scientific and technical expertise to perform very sophisticated and quantitative materials measurements during industrial processing of polymers. Good examples include neutron imaging in a running polymer extruder head, as well as numerous simultaneous scattering and spectroscopy techniques to study the development of crystallinity of polymers during processing. In most institutions, crystallinity is measured as a single end result number from processing, as opposed to NIST’s approach of deeply understanding this extremely important time-based mechanistic phenomenon that results in final polymer properties. This theme of in situ measurement and understanding, which is also evident in other groups within MSED, is essential to enable the next generation of manufacturing in the United States and the world (Industry 4.0 approach). Having quantitative, accurate, in situ measurements enables active, closed-loop process control. This results in more statistically reliable polymer components and a wider application of polymers in society. The Polymers Processing Group is also to be commended for its technology transfer accomplishments, such as the Rheo-Raman-Microscope with ThermoFisher Scientific, TA Instruments, and Anton Paar.

The Functional Nanostructured Materials Group has unique capabilities in synthesis (e.g., materials foundry with capabilities in thin-film deposition, crystal growth, and 2D materials and nanoparticle synthesis), characterization (e.g., suite of magnetic measurements, spectroscopy, electrical measurements, and microscopy) and modeling (e.g., multiscale and machine learning). Its suite of tools for magnetic measurements coupled with modeling and synthesis capabilities define the group. The Functional Nanostructured Materials Group gave three presentations on specific projects, namely Electrochemical Processes, Metrology of Magnetic Materials, and Low Dimensional Electronic Materials. The Electrochemical Processes project team continued work on understanding the electrochemistry of the filling of recessed surface features for building complex structures, which was impressive particularly as it fills a well-defined industrial need. The group developed a new process for bottom-up gold-filling of recessed structures and gained a mechanistic understanding of the process and transitioned the technology from laboratory to manufacturing. In the Metrology of Magnetic Materials effort, there was a transition of the magnetic thin-films device effort to low-D materials project as the former aligns better with the electronics/quantum application space of the low-D project. The stated objectives are very well-aligned with NIST’s missions for development of new measurement methods and instrumentation for characterizing 0D, 1D, 2D and 3D materials and development of new magnetic standard reference materials (SRMs). Much of the efforts in this area are a work in progress. The Low-dimensional Electronic Materials and Magnetic Thin Films team’s goals were to develop libraries and advance metrology of 2D materials and quantum materials. The single-crystal growth facilities are good and include Bridgeman growth, chemical vapor transport, and CVD (crystal vapor deposition) capabilities. The magnetic engineering research facility (MERF) was excellent with coupled synthesis, processing, and novel advanced characterization capabilities. The team is developing advanced imaging and metrology techniques for characterization of spintronic materials and devices. Such expertise, capabilities, and resources are important to the development of emerging electronic and magnetic materials.

Opportunities and Challenges

There is a need for comprehensive strategic planning to define clearly and outline the envisioned trajectory for MSED scientifically, given the limitations on resources. Such planning would consider the number of scientific staff and specific scientific expertise needed, equipment development needs, standards development needs, and prioritize all needed investments. Ideally, the strategic planning might include a shorter-term and a longer-term horizon. Having a well-developed plan that is clearly articulated to MML leadership will go a long way toward obtaining support.

RECOMMENDATION 5-2: The Materials Science and Engineering Division should develop a clear articulation of a broad-based strategic plan of the division and state how that plan reflects the overarching strategic plan of the Material Measurement Laboratory.

PORTFOLIO OF SCIENTIFIC EXPERTISE

Accomplishments

The quality of the NIST scientists and technical staff is very high as is their commitment to the organization. The technical team has the expertise required to accomplish programmatic objectives.

Opportunities and Challenges

However, as indicated above it would be helpful to link to a fuller divisional plan to aid in assessing the scientific portfolio. Additionally it was pointed out that often NIST’s unique and specialized expertise disappears with the retirement of key personnel.

ADEQUACY OF FACILITIES, EQUIPMENT, AND HUMAN RESOURCES

Accomplishments

The equipment and facilities for the work reported was very good to excellent particularly with regard to data quality. Some equipment needs updating, which might best be handled through a thoughtful, strategic equipment renewal process. The division staff has communicated a long list of big-ticket items in terms of equipment that will be needed. These need to be carefully evaluated in a comprehensive strategic plan, together with a prioritization of equipment needs. These processes will need to emphasize “unique” equipment needed to further measurement science, standards and technology, even in areas such as electron microscopy to differentiate NIST from other federal laboratories.

There is clearly a positive culture where permanent staff, postdocs, and visiting researchers feel valued and are proud of their work. This culture translates into almost all postdocs desiring to stay at NIST if that opportunity was available. Postdocs expressed that a positive culture existed for female and minority students.

Opportunities and Challenges

In this era of constrained budgets, it will be necessary to prioritize equipment needs as well as take a survey of building infrastructure. From the overall division presentation, it was apparent that there is significant frustration with the laboratory operational model. An across-the-board 50 percent tax on all

equipment purchases heightens the trade-off between such purchases versus additional staff. For any equipment that is expensive ($1 million to $2 million or more), this effect can be substantial. Such a tax does not exist for large-equipment purchases in many universities, laboratories, or corporations. Second, the NIST working capital fund model for purchase of new equipment requires payback for any purchase from annual operating funds (that is, the funds that would otherwise go to pay staff salaries). Other agencies (such as the National Oceanic and Atmospheric Administration, the Department of Energy, the National Institutes of Health, and the Department of Defense, etc.) place a line item for expensive equipment in their annual budget request and treat equipment funds as separate from operating funds.

The support infrastructure (e.g., buildings) for the staff and equipment needs review and improvement. Although equipment and staff are appropriately prioritized over buildings, there have been instances where failures of the infrastructure compromised equipment with resulting impact on mission delivery. As an example, one laboratory flooded, resulting in damage and equipment downtime.

RECOMMENDATION 5-3: The Material Measurement Laboratory (MML) should evaluate how it budgets new equipment purchases and how this figures in to the resource management in its divisions. The MML should further remain aware of the damage to equipment due to flooding and other problems with buildings and facilities.

The hiring of term-hires (e.g., postdocs) as opposed to permanent hires is an issue. While the permanent hires are often preferred, personnel-related issues such as overhead and so forth appear to have prevented hiring of the latter type.

Mentoring and career planning of postdocs appears somewhat ad hoc with many postdocs expressing “opaqueness” about their career options. It was noted that early stage “beta” testing of a limited mentoring program is under way.

Finally, although diversity and inclusion was a difficult topic to assess in the time permitted, additional work in this area would better establish concrete programs and review processes to assure continued success.

DISSEMINATION OF OUTPUTS

Accomplishments

MSED is addressing stakeholder needs, especially at the higher TRLs. In addition, there was adequate monitoring of stakeholder use and impact of program output. It was noted that there was good dissemination of results using print media (high-impact journals).

Opportunities and Challenges

Results from primary work in MML could be highlighted more. This could be accomplished using forms of media such as YouTube. In addition, a review of the effectiveness of the NIST website in communicating specific examples of unique and transformative contributions to the nation likewise could be beneficial.

In general, many federal laboratories are criticized for their scientific metrics. Typically, a good scientific metric for a full-time scientist will be 4-5 papers in leading journals per year. While this may be true in academia where the focus is on publications, at federal laboratories such as NIST, other mission-related impacts need to be prominently articulated and disseminated, such as critical and transformative advances in measurement science, standards, and technology.

RECOMMENDATION 5-4: The Material Measurement Laboratory should increase its activities aimed at communicating its accomplishments to its customers, collaborators, and audiences. This should include greater effort at highlighting results from the primary work of the laboratory. This could be accomplished using forms of media such as YouTube and improving the effectiveness of the NIST website by adding specific examples of unique and transformative contributions.