This study focuses on optimizing process parameters for producing REE-free MgZnCa alloys using Powder Bed Fusion – Laser Beam (PBF-LB), with the goal of fabricating patient-specific implants for large bone defects. Magnesium alloys produced by additive manufacturing (AM) are prone to increased corrosion rates, which compromise implant integrity. Additionally, the use of rare earth elements (REEs) in biomedical alloys such as WE43 raises environmental and clinical concerns. Gas atomized Mg65Zn30Ca5 (at.%) powder was used for printing on an Aconity Midi PBF-LB machine. The optimization of process parameters included variations in laser power, scan speed, hatch distance, and scan strategy. Density measurements were conducted via image analysis to determine optimal printing parameters. Microstructural characterization of the as-printed parts was performed using Back-Scattered Scanning Electron Microscopy (BS-SEM). Furthermore, single laser tracks were analyzed to understand the microstructure formation in the melt pool as a function of processing and thermal history.Parameter optimization resulted in reduced porosity, achieving a density above 98%. It was observed that increasing the hatch spacing and using a no-rotation scan strategy had a detrimental effect on density. The microstructure was refined but non-uniform due to variations in local thermal gradients along the specimen. Regions with slower cooling rates, subjected to multiple rescanning during the process, showed a microstructure composed of equiaxed MgCaZn grains, α-Mg dendrites, and a eutectic lamellar structure. In contrast, higher cooling rate regions, which were not rescanned, displayed Mg and Zn dendrites. Melt pool analysis indicated predominantly keyhole mode melting for all investigated process parameters.Future work aims to characterize the corrosion properties of these alloys to understand the influence of distinct microstructures, as a first step toward fabricating specimens with improved corrosion resistance.

There is never so far, and probably never will be, an end of history in sociological, but also, in scientific affairs. Although the developments in biomaterials, artificial organs, and all interventions creating biointerphases are relatively recent, the quest is focused mainly on the inert material and less on the bio part (after making sure that toxicity and serious negative responses are dealt with). My proposal is that every improvement in stable or degradable biomaterials should humbly serve the biological entity. Consequently, the refinements in the materials/engineering processes should go hand-in-hand with deeper understanding of the physiological processes in the compromised biological subject. Utilizing several cases, both related to biomaterial science and to human physiology, in general, challenges to “established” ideas will be put forward for discussion.