An Accelerated Paradigm for Developing Mission-Critical Materials

Scientists and engineers at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, are developing a novel materials science paradigm — one that strategically applies artificial intelligence and robotics — that holds promise to dramatically accelerate the process of designing, testing and optimizing metal components for the defense industrial base.

“The Department of Defense needs legacy metallic components to maintain existing systems, but it also needs advanced materials to unlock enhanced performance. The problem is that the industrial base currently can’t keep up with demand for these crucial components,” said Sal Nimer, who is the assistant program manager for APL’s Science of Extreme and Multifunctional Materials program and leads this work. “Furthermore, the slow process for proving out and qualifying alloys hinders our ability to rapidly deploy new cutting-edge materials.”

APL’s new effort, funded by the DoD’s Industrial Base Analysis and Sustainment Program, is called Transforming Evaluation and Testing via Robotics and Acceleration, or TETRA. The name is a reference to the materials science tetrahedron, a conceptual framework for visualizing the relationship between the processing, structure, properties and performance of a material. In this effort, APL is reimagining the traditional tetrahedron. “By integrating robotics and accelerated synthesis and testing methods, we’re developing and validating a suite of tools that makes it possible to produce and evaluate materials at an unprecedented rate,” Nimer said.

“When developing materials for defense needs, it’s not just about the composition of the alloy or system — it’s also about how you shape, treat and refine it,” said Morgan Trexler, who leads the research program area in APL’s Research and Exploratory Development Mission Area. “TETRA has potential to be game-changing because it allows us to simultaneously consider every variable that impacts performance, which until now, has been painstaking and time-consuming, sometimes taking months to achieve what TETRA can accomplish in just a matter of days.”

Reimagining Materials Science

In materials science, processing, structure and properties are dynamically interrelated, with changes in one necessarily affecting the others. However, conventional processes lock scientists into procedures that force them to assess each factor serially, explained Paul Lambert, TETRA co-lead. Scientists typically produce a large ingot of material with a uniform chemical composition, cut it into pieces, place those in a furnace, machine each into a test specimen and then subject each specimen to analysis to test for properties of interest. This sequence is then iteratively repeated for each change made to the material.

“It takes a really long time, it’s really expensive and it’s inefficient,” Lambert said. “With the TETRA lab, we’re working to simultaneously explore all of the different composition and processing variants that influence properties and performance — or at least we aim to do this significantly more rapidly.”

Their approach leverages a method known as combinatorial synthesis to study a variety of chemical compositions. TETRA expands on the standard implementations, which are too limited in size and scale for the rigors of fielded equipment, Lambert explained.

“Materials perform quite differently when scaled up in size, so we are developing methods that focus on development and size scales of interest,” he said. “And traditional combinatorial synthesis often doesn’t account for critical effects of heat treatment and the hot work from forging and other production processes. Our approach will enable understanding and consideration for all of these effects as we develop new alloys and scalable processing approaches.”

Leveraging Advanced Manufacturing

TETRA is leveraging an additive manufacturing technique called blown-powder directed energy deposition, or DED. The process involves a laser melting metal powder as it’s fed into the build area, where it quickly solidifies. This allows for the creation, layer by layer, of dense metal structures, and chemical compositions can be varied in each sample. A single build plate can contain hundreds of alloys, printed into custom-designed 3D specimens, ready to be autonomously tested.

In addition to fabrication via additive manufacturing, the lab will feature a state-of-the-art melting furnace for ultrafast synthesis of custom castings from raw material, custom heat treatment furnaces and hot forging equipment for shaping material and modifying its microstructure, and robotic mechanical property measurement. This combination of capabilities will make TETRA an all-in-one materials research and development facility — the first of its kind.

These same tools for discovering new materials will also enable researchers to troubleshoot the manufacturing of legacy parts, Lambert said, helping to identify why a “surprisingly high” number of parts are rejected for poor properties, even when the root cause of these poor properties is not always clear. “One envisioned future use for the TETRA lab is to help diagnose those kinds of problems with existing parts, in addition to creating new ones,” he said.

The Future: Creating AI Co-Investigators

Eventually, the TETRA team envisions bringing in existing APL capabilities that employ artificial intelligence to discover novel materials for extreme environments.

“TETRA’s cutting-edge methods should integrate seamlessly with our ongoing work in AI-accelerated materials discovery,” Nimer said. “We envision creating an AI ‘co-engineer’ that works alongside human researchers, learning from materials development data to automatically recommend the next tests, or even creating a self-running lab that autonomously designs materials and tests them. We’re not there yet, but we hope we’re building the foundation to enable those instantiations in the future.”