Researchers at Sandia National Laboratories discovered that a 3D printed superalloy could be used to help power plants produce more electricity, while also producing less carbon. The 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. These findings could have wide-ranging impacts on the energy sector, as well as the aerospace industry and automotive industries. They also hint at a new class in similar alloys that are still to be discovered.
“We’re showing that this material can access previously unobtainable combinations of high strength, low weight, and high-temperature resiliency,” said Andrew Kustas, a Sandia scientist. “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.
Power plant turbines require this essential information
According to the US Energy Information Administration, about 80% of the electricity generated in the US is from nuclear power plants or fossil fuels. Both types of facilities depend on heat to turn turbines that produce electricity. How hot the metal turbine parts are can limit power plant efficiency. 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% aluminum, 25% titanium, 13% niobium, 8% zirconium, 8% molybdenum, and 4% tantalum – was stronger at 800 degrees Celsius (1,472 degrees Fahrenheit) 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,” said Sal Rodriguez.
These findings are not limited to energy. Aerospace scientists are looking for lightweight materials that can withstand high temperatures. Nic Argibay from Ames Lab said that Sandia and Ames are working with the industry to see if alloys such as this can be used in automotive manufacturing.
“Electronic structure theory led by Ames Lab was able to provide an understanding of the atomic origins of these useful properties, and we are now in the process of optimizing this new class of alloys to address manufacturing and scalability challenges,” said Nic Argibay.
The Department of Energy and Sandia’s Laboratory Directed Research and Development program funded the research.
Material science is changing
This research further shows how AM can still be used as an efficient and fast way to create new materials. Sandia team members used 3D printers to quickly melt powdered metals, then print a sample.
Sandia’s creation also represents a fundamental shift in alloy development because no single metal makes up more than half the material. Steel is 98% iron, carbon and other elements.
“Iron and a pinch of carbon changed the world,” said Andrew Kustas. “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.”
Scalability and cost
Moving forward, the team is reportedly 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.
“These are extremely complex mixtures,” said Michael Chandross, a Sandia scientist and expert in atomic-scale computer modeling who was not directly involved in the study. “All these metals interact at the microscopic – even the atomic – level, and it’s those interactions that really determine how strong a metal is, how malleable it is, what its melting point will be, and so forth. Our model takes a lot of the guesswork out of metallurgy because it can calculate all that and enable us to predict the performance of a new material before we fabricate it.”
Andrew Kustas acknowledged that there will be challenges. One, it may be difficult to make the superalloy in large quantities without microscopic cracks. This is a common challenge in additive manufacturing. He said that the alloy could not be used in consumer goods because of the high cost of the materials.
“With all those caveats, if this is scalable and we can make a bulk part out of this, it’s a game changer,” concluded Andrew Kustas.