Researchers may have just future-proofed turbines in the aerospace and energy industry

Researchers have come up with a new way to use 3D printing to make a new superalloy.
Christopher McFadden

A group of researchers has developed a new superalloy resistant to high temperatures. This could if ever brought into production, prove revolutionary for the future of turbines.

At present, steam turbine blades, bearings, and seals are made of metal that tends to soften and elongate well before its melting point, which is one issue restricting the output of today's power plants. If these issues are resolved, it is possible to increase the temperature of anything that uses a steam turbine to convert heat into electricity.

This would increase its efficiency and decrease waste heat.

However, a new high-performance superalloy that can be printed in three dimensions by scientists at Sandia Labs, Ames National Laboratory, and Iowa State University is said to be stronger and lighter than the most advanced high-temperature alloys now in use.

This substance is an example of a "multi-principal-element superalloy," or MPES. It comprises 42 percent aluminum, 25 percent titanium, 13 percent niobium, 8 percent zirconium, 8 percent molybdenum, and 4 percent tantalum. Multi-principal-element alloys have higher concentrations of three or more elements than most alloys, mostly made of one main element and small amounts of other elements to improve certain properties.

The research team claims that a wide range of these alloys exhibits excellent potential in metrics like strength-to-weight, fracture toughness, corrosion and radiation resistance, wear resistance, etc. However, the MPES subset this team has investigated performs exceptionally well in high-temperature conditions.

According to the researchers, this finding suggests a more significant class of MPES materials just waiting to be studied and have exciting immediate promise in energy and aerospace. They warn that more improvements in 3D printing technology are needed before they can reliably make large parts out of these alloys without microscopic cracks and that the feedstock contains some expensive metals that will make it hard to scale up this particular MPES for use in applications where cost is a top priority.

“With all those caveats, if this is scalable and we can make a bulk part out of this, it’s a game changer,” says Sandia scientist Andrew Kustas in a press release. “We’re showing that this material can access previously unobtainable combinations of high strength, low weight, and high-temperature resiliency. We think part of the reason we achieved this is because of the additive manufacturing approach,” he added.

You can view the study for yourself in the journal Applied Materials Today.

Study abstract: 

“Materials are needed that can tolerate increasingly harsh environments, especially ones that retain high strength at extreme temperatures. Higher melting temperature alloys, like those consisting primarily of refractory elements, can greatly increase the efficiency of turbomachinery used in grid electricity production worldwide. Existing alloys, including Ni- and Co-based superalloys, used in components like turbine blades, bearings, and seals, remain a performance limiting factor due to their propensity, despite extensive optimization efforts, for softening and diffusion-driven elongation at temperatures often well above half their melting point. To address this critical materials challenge, we present results from integrating additive manufacturing and alloy design to guide significant improvements in performance via traditionally difficult-to-manufacture refractory alloys. We present an example of a multi-principal element alloy (MPEA), consisting of five refractory elements and aluminum, that exhibited high hardness and specific strengt,h surpassing other known alloys, including superalloys. The alloy shows negligible softening up to 800°C and consists of four compositionally distinct phases, in distinction to previous work on MPEAs. Density functional theory calculations reveal a thermodynamic explanation for the observed temperature-independent hardness and favorability for the formation of this multiplicity of phases.”

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