Citation: Neˇ cas, D.; Marek, I.; Pinc, J.; Vojtˇ ech, D.; Kubásek, J. Advanced Zinc–Magnesium Alloys Prepared by Mechanical Alloying and Spark Plasma Sintering. Materials 2022, 15, 5272. https://doi.org/10.3390/ ma15155272 Academic Editor: Joan-Josep Suñol Received: 24 June 2022 Accepted: 26 July 2022 Published: 30 July 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, 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/). materials Article Advanced Zinc–Magnesium Alloys Prepared by Mechanical Alloying and Spark Plasma Sintering David Neˇ cas 1, * , Ivo Marek 1 , Jan Pinc 2 , Dalibor Vojtˇ ech 1 and Jiˇ rí Kubásek 1, * 1 Department of Metals and Corrosion Engineering, Faculty of Chemical Technology, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague, Czech Republic; mareki@vscht.cz (I.M.); vojtechd@vscht.cz (D.V.) 2 Department of Functional Materials, Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, 182 21 Prague, Czech Republic; pincik789@gmail.com * Correspondence: necasd@vscht.cz (D.N.); kubasekj@vscht.cz (J.K.) Abstract: Zinc and its alloys are considered as promising materials for the preparation of biodegrad- able medical devices (stents and bone fixation screws) due to their enhanced biocompatibility. These materials must achieve an ideal combination of mechanical and corrosion properties that can be influenced by alloying or thermomechanical processes. This paper presents the effects of different mechanical alloying (MA) parameters on the composition of Zn-1Mg powder. At the same time, this study describes the influence of preparation by MA on Zn-6Mg and Zn-16Mg alloys. The se- lected powders were compacted by the spark plasma sintering (SPS) method. Subsequently, their microstructures were studied and their mechanical properties were tested. The overall process led to a significant grain refinement (629 ± 274 nm for Zn-1Mg) and the formation of new intermetallic phases (Mg 2 Zn 11 , MgZn 2 ). The compressive properties of the sintered samples were mainly related to the concentration of the alloying elements, where an increase in concentration led to an improvement in strength but a deterioration in ductility. According to the obtained results, the best properties were obtained for the Zn-1Mg alloy. Keywords: zinc; magnesium; mechanical alloying; powder metallurgy; mechanical properties 1. Introduction Biomaterials are artificial or natural materials used for the manufacturing of structures, which replace damaged or lost human tissue in order to restore its previous function [1]. These medical devices can be divided into three groups according to their interaction with the human body. Bioinert materials (Ti-6Al-4V, Co-28Cr-6Mo, 316 L stainless steel) are characterized by excellent corrosion resistance and a relatively high modulus of elasticity. However, such materials interact insufficiently with tissue and the high modulus also promotes a stress shielding effect. This can ultimately lead to implant loosening. Bioactive materials (surface-modified titanium alloys, bioceramics, hydroxyapatite) interact with the surrounding tissue, which improves regeneration and bonding with the implant. Finally, biodegradable materials (Fe-, Mg- and Zn-based alloys) gradually dissolve in the body and completely degrade once their function has been fulfilled [2–6]. Among these groups, the last group seems to be the most intensively studied with an interest in finding suitable materials with appropriate properties. Great interest lies particularly in zinc and its alloys. Zinc is an essential element for various functions in the human organism and has a rea- sonable corrosion rate. Compared to Mg and Fe, its corrosion processes are not associated with the formation of hydrogen or toxic corrosion products, respectively. Therefore, zinc and its alloys have been studied in the last decade as promising biodegradable materials [7]. However, the mechanical properties of pure zinc are insufficient for such applications. The tensile strength of zinc in the as-cast conditions is approximately 20 MPa and the elongation to failure reached only 0.2% [8]. Therefore, various alloying elements (Mg, Mn, Materials 2022, 15, 5272. https://doi.org/10.3390/ma15155272 https://www.mdpi.com/journal/materials