HRL’s researchers have made a revolutionary breakthrough in metallurgy that solves both a major 21st century difficulty and a significant problem dating back to the origins of high-strength aluminum. Metallurgy is a discipline that includes the physics and chemistry of metal structure as well as the link between a metal’s microstructure; how the metal is processed, and how those factors affect the metal’s properties. The HRL team just developed a technique called nanofunctionalization. It enables successful 3D printing of high-strength aluminum alloys, including those of the 6000 and 7000 series commonly used in aerospace and automotive applications. BRENNAN: Of the thousands of commercially available metal alloy systems, only a handful of about ten alloys can be readily 3D printed. Until now, the higher strength alloys, although very desirable for engineering applications such as airplane fuselages, had to be fastened by riveting or other methods because they were not weldable. They were also not available for 3D printing – known as, additive manufacturing. We’ve developed a methodology that allows us to 3D print any metal system. HUNTER: Additive manufacturing of metals is essentially equivalent to welding. You’re taking layer by layer and welding each layer on top of another. And so, that adds the constraint that the metals you put in there generally have to be weldable. So what we did at HRL, was we took an unweldable metal and made it weldable so that it can now be processed in conventional additive manufacturing equipment. In 3D printing, parts begin as powder fed into the printer. Construction begins as the machine lays down a thin layer of metal powder that is melted and resolidified by a rastering laser only in the areas that will make up the final part. As the metal in each successive layer fuses together, it also fuses to the layer below. The new breakthrough is a treatment for the metal powder that controls the way the material solidifies in this process, without hot cracking and other problems that were inherent in 3D printing with these materials. Because melting and solidifying locally is essentially welding them together, this treatment can also be used to weld previously unweldable alloys. HUNTER: We know that we can induce lattice-matched nucleation. So that’s essentially taking these atomic-scale phenomena, where these atoms need to line up perfectly in the right spot to create these micron-sized grains, which then create millimeter-sized features, which are ultimately built into a meter-sized part, which then can then be used on a variety of different vehicles. This is, in it’s essence, true optimization from the atomic scale up to the component scale. Now that we have 3D printed a metal that before now could never before be 3D printed, what we’ve done is opened the door so that really any new metal can be processed using additive manufacturing equipment. This amazing leap in technology could launch the future of automotive and aircraft parts that can be manufactured faster, cheaper, more accurately, and with high-strength materials never before available. A paper on this topic has been published in Nature, and can be found online, at nature.com.