Cornell researchers adjust grain size and morphology in alloys using targeted manipulation of phase stability.
Every engineer worth their salt understands that even the smallest differences can end up make a big difference to product performance. Case in point: the microstructure of 3D printed metals has a profound impact on their material properties. That’s why controlling the evolution of a 3D printed part’s microstructure during the phase changes the occur in the metal additive manufacturing (AM) process is the subject of intense research.
The latest advancement in this area comes from engineers at Cornell University, who have discovered a way to control grain size and morphology in multiprincipal element alloys (MPEAs) during the metal AM process.
“A major problem is that most of the materials we print form column-like structures that can weaken the material in certain directions,” said Atieh Moridi in a press release. “We discovered that by adjusting the composition of the alloys, we can essentially disrupt these column-like structures and make a more uniform material.” Moridi is assistant professor in the Sibley School of Mechanical and Aerospace Engineering and senior author of the published research.
By adjusting the relative amounts of manganese and iron in their starting material, Moridi and her team team disrupted columnar grain growth, significantly reduced grain size, and improved the yield strength of the finished metal.
“Microstructural features, like grain size, are the building blocks that govern material performance and properties” Moridi said. “The material composition controls the phase stability, which was the key for us to control the microstructure.”
“The difficult part was trying to resolve these very short spans of time where the material goes from liquid state to solid state,” explained first author Akane Wakai. The team overcame this roadblock by utilizing the Cornell High Energy Synchrotron Source (CHESS) to obtain fraction-of-a-second data about their materials during the printing process. In the best-performing sample, the researchers found evidence of an intermediate phase that can help disrupt those column-like grains and refine the grain structure.
“The findings from this research can be used for real-life applications to create more reliable materials that enable even better performance,” Wakai said. “Not too far into the future, we’ll start seeing 3D printed metal parts, even in consumer products like cars or electronics.”
The research is published in the journal Nature Communications.
