If you wanted to 3D print an object that was magnetic in some areas only, you'd typically have to print two separate items out of different metals, then join them together. A new take on an existing technique, however, allows for the printing of single objects with gradient magnetic qualities.
The process was developed by a consortium led by Russia's Skolkovo Institute of Science and Technology. It's based around an established 3D printing method known as directed energy deposition, in which a heat source such as a laser is used to melt metal powder as it's being dispensed from a nozzle.
Ordinarily, the type of metal powder remains the same throughout one print job. Utilizing an InssTek MX-1000 3D printer, however, the researchers were able to start out by dispensing a powder made of one metal, then gradually blend it with another metal powder until eventually only the other metal was being dispensed.
The two metals were both alloys, the first being aluminum bronze (copper, aluminum, and iron) and the second being marine-grade stainless steel (mainly iron, chromium, and nickel). Interestingly, neither one is magnetic on its own, in that they're not attracted to permanently magnetic metals.
When they're mixed together, though, the resulting blended alloy exhibits "soft ferromagnetic" qualities. This means that although it isn't permanently magnetic itself, it sticks to "hard ferromagnetic" metals that are. The soft ferromagnetic effect is strongest in the middle of the printed object, where the aluminum bronze and marine-grade stainless steel are mixed in a 50/50 blend, then tapers off toward the ends as either one metal or the other becomes prominent.
"Gradient soft magnetic alloys could find applications in machine engineering, for example, in electrical motors," says principal investigator Stanislav Evlashin. "Our findings show that directed energy deposition is not just a way to 3D-print gradient materials, but also a way to discover new alloys. Besides that, the technology is highly efficient and suitable for manufacturing even large-size parts quickly."
A paper on the research – which also involved scientists from Russia's St. Petersburg State Marine Technical University, National Research Center Kurchatov Institute, and Belgorod State University – was recently published in The Journal of Materials Processing Technology.
Source: Skoltech
