3D-Printable Alloy Can Take the Heat

Subheadline

A NASA-developed metallic alloy fills a big materials gap for printed parts

Two requirements that rockets and high-speed jet engines have in common are durability and the ability to function in extreme temperatures. Until now, additive manufacturing, commonly known as 3D printing, could only produce certain engine components, because there were no affordable metal alloys for durable parts in the mid-temperature range, from 1,900°F to 2,400°F. Expensive higher-heat alloys were the only option until NASA developed GRX-810. This was the first time NASA used computational modeling to develop a custom alloy for 3D printing, but this novel material also required a new manufacturing process.

A team led by Tim Smith, materials engineer with NASA’s Glenn Research Center in Cleveland, developed the new alloy. Before any physical material was prepared, the team simulated and tested alloy mixtures on a computer to determine which recipes would yield the necessary properties.

“We used different elements, adding different amounts of each, and looked at the properties each iteration had,” he said. The primary metals in GRX-810 include nickel, cobalt, and chrome. But even with the right mix, the powdered metal particles required a ceramic oxide coating to increase heat resistance and other performance. Known as oxide dispersion strengthened (ODS) alloys, these powders were impossible to manufacture at a reasonable cost when the project started. “We were also trying to develop new manufacturing techniques to incorporate nano-oxides into a metal when you 3D print,” said Smith.

The advanced dispersion coating technique Smith and his team developed employs resonant acoustic mixing. Rapid vibration is applied to a container filled with the metal powder and nano-oxide particles. The vibration evenly coats each metal particle with the oxide, making them inseparable. Even if a manufactured part is ground down to powder and reused, the next component will have the benefits of ODS.

“If you look at the metal powder under a microscope, it looks like powdered-sugar donut holes. The metal is the donut, and the nano-oxide material is the powdered sugar,” said Smith.

The benefits over common alloys are significant – higher heat resistance and increased durability. Smith estimated that GRX-10 could last up to a year at 2,000°F under stress loads that would crack any other affordable alloy within hours.

Elementum 3D, an Erie, Colorado-based company, produces GRX-810 for customers in quantities ranging from small batches to one ton or more. The company has a co-exclusive license for the NASA patented alloy and manufacturing process and continues to work with the agency under a Space Act Agreement to improve the material.

“A material under stress or a heavy load at high temperature can start to deform and stretch almost like taffy,” said Jeremy Iten, chief technical officer with Elementum 3D. “Initial tests done on the large-scale production of our GRX-810 alloy showed a lifespan that’s twice as long as the small-batch material NASA produced, and those were already fantastic.”

Commercial space and other industries, including aviation, are testing GRX-810 for various applications, Iten said. For example, flow sensors monitor the speed of gases flowing through a turbine, helping engineers optimize engine performance. However, they can burn out in minutes due to extreme temperatures. One Elementum 3D customer, Vectoflow, is testing a GRX-810 flow sensor. This could improve airplane fuel efficiency, reduce emissions, and eliminate frequent hardware replacements.