As the world looks for ways to cut greenhouse gas emissions, researchers from Sandia National Laboratories have shown that a new 3D-printed superalloy could help power plants generate more electricity while producing less carbon.
Sandia scientists, collaborating with researchers at Ames National Laboratory, Iowa State University, and Bruker Corp., used a 3D printer to create a high-performance metal alloy, or superalloy, with an unusual composition that makes it stronger and lighter than state-of-the-art materials currently used in gas turbine machinery. The findings could have broad impacts across the energy sector as well as the aerospace and automotive industries, and hints at a new class of similar alloys waiting to be discovered.
“We’re showing that this material can access previously unobtainable combinations of high strength, low weight and high-temperature resiliency,” Sandia Scientist Andrew Kustas said. “We think part of the reason we achieved this is because of the additive manufacturing approach.” The team published their findings in the journal Applied Materials Today.
About 80 percent of electricity in the U.S. comes from fossil fuel or nuclear power plants, according to the U.S. Energy Information Administration. Both types of facilities rely on heat to turn turbines that generate electricity. Power plant efficiency is limited by how hot metal turbine parts can get. If turbines can operate at higher temperatures, “then more energy can be converted to electricity while reducing the amount of waste heat released to the environment,” said Sal Rodriguez, a Sandia nuclear engineer who did not participate in the research.
Sandia’s experiments showed that the new superalloy — 42 percent aluminum, 25 percent titanium, 13 percent niobium, 8 percent zirconium, 8 percent molybdenum and 4 percent tantalum — was stronger at 800 °C (1,472 °F) than many other high-performance alloys, including those currently used in turbine parts, and still stronger when it was brought back down to room temperature.
“This is therefore a win-win for more economical energy and for the environment,” Rodriguez said.
Energy is not the only industry that could benefit from the findings. Aerospace researchers seek out lightweight materials that stay strong in high heat. Additionally, Ames Lab Scientist Nic Argibay said Ames and Sandia are partnering with industry to explore how alloys like this could be used in the automotive industry.
Additive manufacturing is known as a versatile and energy-efficient manufacturing method. A common printing technique uses a high-power laser to flash-melt a material, usually a plastic or a metal. The printer then deposits that material in layers, building an object as the molten material rapidly cools and solidifies.
But this new research demonstrates how the technology also can be repurposed as a fast, efficient way to craft new materials. Sandia team members used a 3D printer to quickly melt together powdered metals and then immediately print a sample of it.
Sandia’s creation also represents a fundamental shift in alloy development because no single metal makes up more than half the material. By comparison, steel is about 98 percent iron combined with carbon, among other elements.
“Iron and a pinch of carbon changed the world,” Kustas said. “We have a lot of examples of where we have combined two or three elements to make a useful engineering alloy. Now, we’re starting to go into four or five or beyond within a single material. And that’s when it really starts to get interesting and challenging from materials science and metallurgical perspectives.”
Moving forward, the team is interested in exploring whether advanced computer modeling techniques could help researchers discover more members of what could be a new class of high-performance, additive manufacturing-forward superalloys.
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