High performance permanent magnets based on Nd-Fe-B are produced by well-established powder metallurgical routes [1] - typically with a limited choice of shapes based on cuboids or cylinders. Driven by the strongly increasing demand of these magnets for energy and e-mobility related applications [2], the efficient use of the material during production becomes more and more important. The recent growing interest in additive manufacturing (AM) of functional materials inspires the use of the Nd-Fe-B materials for newly developed production ideas such as complex shape magnets with optimized local stray field geometries and multi-material printing to obtain hybrid parts with integrated magnets [3,4].  
It is known that the development of the AM process requires a qualified starting material and the supply of metal powders for AM is limited in general. Thus, the development of Nd-Fe-B-based starting materials for commercial production is the goal of the EIT Raw Materials funded project 3DREMAG. The outlined route for the large scale production is derived from the existing powder-metallurgical route starting from ground strip cast flakes followed by a plasma spheroidization step.
It is very challenging to (a) obtain fully dense Nd-Fe-B magnets by AM and (b) the specific microstructure of uniform micrometer sized Nd$_2$Fe$_{14}$B grains separated by a rare-earth rich grain boundary phase that has to be established to achieve high remanence and coercivity [1,2,5,6]. Spherical particle morphology and proper particle size distribution to assure good flowability and packing density for the powder are desired for application in laser powder bed fusion. Special considerations are given to the process challenges such as oxidation, particle shape and size distribution as well as the magnetic properties and density of printed parts.

This work was supported financially by EIT Raw Materials in the Project “3DREMAG: 3D printing of rare-earth permanent magnets”, URL: https://3DREMAG.eu.

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