Biodegradable metallic implants are desirable as bone substitutes since they eliminate the need for additional revision surgeries often associated with permanent implants. The challenge for biodegradable metals, however, is to ensure that degradation occurs at such rates that the mechanical integrity of the implant is maintained while promoting the necessary tissue regeneration to heal the bone. This requires the appropriate combination of material, component design, and manufacturing method. In this regard, magnesium (Mg) emerges as an ideal candidate amongst other biodegradable metals due to its abundance in the human body and its ability to stimulate new tissue growth. Also, when combined with advanced manufacturing methods like additive manufacturing (AM), the prospect of developing degradable patient-specific implants with bone-like structures becomes increasingly viable.

In this work, laser-powder bed fusion (L-PBF) was used to fabricate WE43 Mg alloy scaffolds desired as bone substitutes. WE43 is considered a ‘benchmark’ for biomedical Mg alloys since it is the basis for most clinically approved Mg-based implants. To further the clinical benefits of Mg alloys, fabrication of porous tissue-scaffolds thereof is desired. Scaffolds are beneficial for bone replacement since they serve as an anchor to support the defected tissues while facilitating the diffusion of nutrients and oxygen to cells. Nevertheless, the complexity of scaffold design along with the challenges of printing Mg alloys motivated this study.

Process optimization was first performed through systematic printing of struts with varying thicknesses (0.2 to 0.8mm) and inclination angles (10 to 90°). The struts were first evaluated for defects and geometric mismatches to identify the boundary conditions regarding minimum thickness and inclination. These results were then used to fabricate tailored strut-based geometries and triply periodic minimal surfaces. The degradation rates of these structures were determined and compared to those of WE43 bulk cubes. The results reveal the effect of pore size, strut thickness, and scaffold geometry on degradation rate, which could be linked to the differences in the resulting microstructure. Overall, this study highlights the interplay among component geometry, printability, and degradability of L-PBF-processed WE43, as a critical step towards manufacturing WE43 porous scaffolds as bone substitutes.