Additive manufacturing is a very rapidly developing industrial field. It opens many possibilities for the fast fabrication of complex-shaped products and devices, including functional materials and smart structures. This paper presents an overview of polymer 3D printing technologies currently used to produce magnetic materials and devices based on them. Technologies such as filament-fused modeling (FDM), direct ink writing (DIW), stereolithography (SLA), and binder jetting (BJ) are discussed. Their technological features, such as the optimal concentration of the filler, the shape and size of the filler particles, printing modes, etc., are considered to obtain bulk products with a high degree of detail and with a high level of magnetic properties. The polymer 3D technologies are compared with conventional technologies for manufacturing polymer-bonded magnets and with metal 3D technologies. This paper shows prospective areas of application of 3D polymer technologies for fabricating the magnetic elements of complex shapes, such as shim elements with an optimized shape and topology; advanced transformer cores; sensors; and, in particular, the fabrication of soft robots with a fast response to magnetic stimuli and composites based on smart fillers.

Additive manufacturing (AM) is a rapidly developing technical field that is becoming an irreplaceable tool to fabricate unique complex-shaped parts in aerospace, the automotive industry, medicine, and so on. One of the most promising directions for AM application is the design and production of multi-material components with different types of chemical, structural, and architectural gradients that also promote a breakthrough in bio-inspired approaches. At the moment there are a lot of different AM techniques involving various types of materials. This paper represents a review of extrusion-based AM techniques using metal-polymer composites for structural metal parts fabrication. These methods are significantly cheaper than powder bed fusion (PBF) and directed energy deposition (DED) techniques, though have a lower degree of part detail. Thus, they can be used for low-scale production of the parts that are not rentable to produce with PBF and DED. Multi-material structures application in machinery, main aspects of feedstock preparation, the subsequent steps of extrusion-based 3D printing, and the following treatment for manufacturing single-metallic and multi-metallic parts are considered. Main challenges and recommendations are also discussed. Multi-metallic extrusion-based 3D printing is just a nascent trend requiring further wide investigation, though even now it shows pretty interesting results.

In this paper, a novel approach to obtain a ferromagnetic material for smart applications was implied. A combination of mechanical alloying (MA) and plasma spheroidization (PS) was applied to produce Ni₃₆Al₂₇Co₃₇ spherical powder. Then its structure was systematically studied. It was shown that homogenization of the structure occurs due to mechanism of layered structure formation. The dependence of the lamella thickness on the energy dose input at MA was defined. It was found that 14.7 W⋅h/g is sufficient to obtain lamella thickness of 1 μm and less. The low-energy mode of a planetary mill with rotation speeds of the main disk/bowl of 150/−300 rpm makes it possible to achieve a uniform element distribution upon a minimal amount of impurity. During MA in an attritor Ni₃Al-type intermetallic compounds are formed that result in more intensive degradation in particle size. Plasma spheroidization of the powder after MA allowed obtaining Ni₃₆Al₂₇Co₃₇ spherical powder. The powder had a fine β + γ-structure. The particle size distribution remains almost unchanged compared to the MA stage. Coercivity of the powder is 79 Oe. The powder obtained meets the requirements of selective laser melting technology, but also can be utilized as a functional filler in various magnetic composites.