_Applied_  
_sciences_  
_Article_  
**Effects of Carbon Doping and Annealing Temperature on Magnetic MnAl Powders and MnAl Polymeric Composites**  
**[PERSON] \({}^{1}\)\({}^{\copyright}\), [PERSON] \({}^{2,3}\), [PERSON] \({}^{4}\), [PERSON] \({}^{5}\), [PERSON] \({}^{1,6}\) and [PERSON] \({}^{2,3,4,\copyright}\)  
\({}^{1}\) Department of Physics, Faculty of Science, King Mongkut's Institute of Technology Ladkrabang, Ladkrabang, Bangkok 10520, Thailand, 616050766 knit.ac.th (W.T. ); [EMAIL_ADDRESS] (C.R.) \({}^{2}\) Functional Materials and Nanotechnology Center of Excellence, Wailiak University, Nakhon Si Thammarat 80160, Thailand; [EMAIL_ADDRESS]  
\({}^{3}\) Thailand Center of Excellence in Physics, Ministry of Higher Education, Science, Research and Innovation, Bangkok 10400, Thailand  
\({}^{4}\) Division of Physics, School of Science, Wailiak University, Nakhon Si Thammarat 80160, Thailand; panissa.saetmail.wua.ac.th  
\({}^{5}\) Department of Physics, Faculty of Science, Kasetsart University, Chatchak, Bangkok 10900, Thailand; [EMAIL_ADDRESS]  
\({}^{6}\) Center of Excellence in Smart Materials Research and Innovation, King Mongkut's Institute of Technology Ladkrabang, Ladkrabang, Bangkok 10520, Thailand  
\({}^{*}\) Correspondence: [EMAIL_ADDRESS]; Tel. : +66-75-672-005  
**Featured Application: Granular ferromagnetic MnAl incorporated into polymeric matrix can be implemented in 3D-printing of rare-earth-free magnets without forming into filaments. **  
**Citation:** [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] Effects of Carbon Doping and Annealing Temperature on Magnetic MnAl Powders and MnAl Polymeric Composites. _Appl. Sci._**2021**, _11_, 2067. [[https://doi.org/10.3309/appl1052067](https://doi.org/10.3309/appl1052067)]([https://doi.org/10.3309/appl1052067](https://doi.org/10.3309/appl1052067))  
Academic Editor: [PERSON]  
Received: 20 January 2021  
Accepted: 22 February 2021  
Published: 26 February 2021  
**Published: 26 February 2021**  
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**C copyright:** 0221 by the authors. License MDP, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)]([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/))). **Copyright:** 0221 by the authors. License MDP, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)]([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/))). **Feard Application: Granular ferromagnetic MnAl incorporated into polymeric matrix can be implemented in 3D-printing of rare-earth-free magnets without forming into filaments. **  
**Abstract:** Process parameters leading to magnetic polymer composites, an essential ingredient in the additive manufacturing of rare-earth-free magnets, are investigated. The induction melting of manganese (Mn) and aluminum (Al), and subsequent annealing at 450, 500, or 550 \({}^{\circ}\)C for 20 min, gave rise to ferromagnetic \(\tau\)-MnAl phase, as well as other phases. The nonmagnetic Al\({}_{4}\)C\({}_{3}\) and oxide phases were then removed by the magnetic separation. Magnetic powders from the magnetic separation were incorporated in polylactic acid (PLA) matrix via a solution route. The remanent magnetization as high as 4.3 emu/g in the powder form was reduced to 2.3-2.6 emu/g in the composites. The reduction in coercivity was minimal, and the largest value of 814 Oe was obtained when the powder annealed at 450 \({}^{\circ}\)C was loaded in the composite. The phase composition and hence magnetic properties were even more sensitive to the carbon (C) doping.