Superalloy could help power plants generate more electricity while producing less carbon, according to a new study.
Scientists from Sandia National Laboratories, US, created a superalloy, with an unusual composition that makes it stronger and lighter than state-of-the-art materials currently used in gas turbine machinery, the study said. A superalloy, or a high-performance metal alloy, is an alloy with the ability to operate at a high fraction of its melting point.
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As the world looks for ways to cut greenhouse gas emissions, 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, the study said.
The team published their findings in the journal Applied Materials Today. "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," said Kustas.
Additive manufacturing, also called 3D printing, 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, the scientists said, steel is about 98 per cent 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," said Kustas.
About 80 per cent of electricity in the US comes from fossil fuel or nuclear power plants, according to the US 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.
According to the study, Sandia's experiments showed that the new superalloy - 42 per cent aluminum, 25 per cent titanium, 13 per cent niobium, 8 per cent zirconium, 8 per cent molybdenum and 4 per cent tantalum - was stronger at 800 degrees Celsius, or 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," 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, the researchers said.
Ames National Laboratory, Iowa State University, US, scientist Nic Argibay said Ames and Sandia are partnering with industry to explore how alloys like this could be used in the automotive industry, they said.
"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," Argibay said.
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