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3D-printed alloy 600 times as resistant to stress as existing alloys

A team of materials scientists from NASA working with a colleague from The Ohio State University and another from HX5 LLC has developed a 3D printing process that produces an alloy that is much more resistant to stress than others now in use. Their study is reported in Nature.

As scientists develop new ways to produce energy and explore space, a need has arisen for materials that can survive under extreme conditions—those used to make rocket nozzles, for example. To meet that need, materials scientists have been creating alloys that are ever more resistant to heat and other stressful elements. In this new effort, the research team took a big step forward by developing a 3D process to create an alloy that is much more resilient than anything created thus far.

Prior research has shown that adding ceramic to metal alloys gives them more resilience. Unfortunately, adding ceramic has proven to be problematic due to the difference in characteristics of metals and ceramics—the lighter ceramic bits tend to float to the top when added to molten metal. To overcome that problem, the researchers turned to 3D printing.

They used an "ink" made of a mixture of cobalt, nickel and chrome particles and programmed the printer to add a dusting of yttrium oxide powder to each layer of ink. As the printing progresses, a layer of the metal alloy is printed onto a surface, followed by a fine layer of yttrium oxide particles, which are then heated with a laser, forcing the particles into the metal alloy. The result is a layer of metal alloy infused with tiny pieces of ceramic material. As the process continues, an object is created—a nozzle, for example. The researchers call the new alloy GRX-810.

The team tested their new material using the "creep test," whereby a test material is subjected to high temperatures while also carrying a heavy load to provide stress. The longer it lasts, the more resistant the material. Current top materials typically last approximately 10 hours— GRX-810 lasted for 6,500 hours.