Scientists at Skoltech and their colleagues used a 3D printer to fuse two materials into an alloy whose composition continually changes from region to sample to sample, giving the alloy gradient magnetic properties. Despite the non-magnetic nature of the constituent materials, the alloy exhibits magnetic properties. Posted in The Journal of Materials Processing Technology, the study also offers a theoretical explanation of the phenomenon.
Once perceived as a simple novelty tool for rapid prototyping, 3D printing has become an industrial technology in its own right used to produce aircraft parts, patient-specific implants and prostheses, bespoke jewelry and footwear, among others.
The main advantage of 3D printing is the ability to produce objects with very complex shapes that are impossible or too expensive to manufacture with conventional manufacturing techniques, such as molding, rolling and stamping. The technology also allows for faster and riskier prototyping, as well as greater flexibility in terms of product customization and the number of items produced. And then there is the added benefit of reduced waste.
One of the limitations of 3D printing is that it tends to use a homogeneous material or mixture throughout the produced item. By varying the composition from one part of the article to another, it could be endowed with continuously changing properties.
An example of this would be a rod made of an alloy of two metals whose ratio goes from 100% metal A to fifty-fifty, to 100% metal B, and so on. Provided that the metals in question mix well, without giving rise to defects, the gradient properties of the rod – including magnetic ones – could be technologically useful, for example for motor rotors, magnetic encoder tapes or transformers.
The authors of a recent study led by Skoltech published in The Journal of Materials Processing Technology report an experience where they produced such an alloy. Its two components – metals A and B above – are alloys themselves: aluminum bronze (copper, aluminum and iron) and marine grade stainless steel (mainly iron, chromium and nickel. ). Both are technically known as paramagnetics, or “non-magnetic” in layman’s terms. That is, they do not stick to a magnet. Yet, when mixed in equal proportions, the resulting alloy turns out to be a “soft” ferromagnetic. That is, it is attracted to “hard” ferromagnetics – like that in the refrigerator – but does not become so itself.
“We used these two paramagnetic materials to create a gradient alloy with an InssTek MX-1000 3D printer. It uses a technique called directed energy deposition, which involves depositing powdered material from a nozzle and simultaneously melting it with a laser. The resulting alloy exhibited ferromagnetic properties to an extent that depended on the ratio of the two constituent materials, ”said lead author of the study, Oleg Dubinin, of Skoltech’s Additive Manufacturing Lab.
“Our study also provides a theoretical explanation for the emergence of ferromagnetic properties in the alloy in terms of atomic structure,” continued the researcher. “While the two original materials have a face-centered cubic crystal structure, their combination results in a body-centered cubic structure. “
In the first, metal atoms sit in the corners of imaginary cubes and on their faces. In the latter, there are metal atoms in the center of invisible cubes instead of on their faces. This second arrangement gives the material its ferromagnetic properties.
“Gradient soft magnetic alloys could find applications in machine engineering, for example in electric motors,” commented PI Stanislav Evlashin, a leading researcher at Skoltech. “Our results show that directed energy deposition is not only a way to 3D print degraded materials, but also a way to discover new alloys. In addition to this, the technology is very efficient and suitable for the rapid manufacture of even large parts. “
In addition to Skoltech researchers, the study reported in this article features scientists from St. Petersburg State Marine Technical University, the Kurchatov Institute National Research Center, and Belgorod State University. .
Skoltech is a private international university located in Russia. Established in 2011 in collaboration with the Massachusetts Institute of Technology (MIT), Skoltech cultivates a new generation of leaders in science, technology and business, conducts research in groundbreaking areas and promotes technological innovation in the goal of solving critical problems. problems facing Russia and the world. Skoltech focuses on six priority areas: artificial intelligence and communications, life sciences and health, advanced engineering and advanced materials, energy efficiency and ESG, photonics and quantum technologies, advanced studies. Website: https://www.skoltech.ru/.
Journal of Materials Processing Technology
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Gradient soft magnetic materials produced by additive manufacturing from non-magnetic powders
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