Laser Hatch Distance Can Tune Corrosion Behavior and Mechanical Properties While Maintaining the In Vitro
Hanna Nilsson Åhman1,2, Niccolò De Berardinis1,3, Lisa Larsson1
1Division of Biomedical Engineering, Department of Materials Science and Engineering, Uppsala University, Uppsala, 751 03, Sweden.
Abstract:
Powder bed fusion laser beam (PBF-LB) of Mg alloys shows strong potential for biodegradable, patient-specific implants. A key challenge is achieving adequate corrosion resistance and mechanical strength while maintaining biocompatibility. This study investigates whether varying hatch distance can balance these properties in PBF-LB processed WE43 (Mg-4Y-3RE-Zr; RE: rare earth elements). Optimal laser parameters were developed for hatch distances of 40, 50, and 60 μm (h40, h50, and h60), and samples were analyzed for microstructure, corrosion resistance, and mechanical properties. Results showed that h60 had a weaker texture and narrower grain size distribution, with fewer grains under 200 μm2. It also had the lowest degradation rate while maintaining comparable ultimate tensile strength to h50, which had the highest degradation rate. The improved corrosion resistance in h60 was attributed to a more homogeneous distribution of Mg-RE precipitates due to fewer and more homogenously distributed grain boundaries. Extracts from h60 and control materials were used to culture osteoblasts, showing no cytotoxicity after 3 days. Notably, osteoblasts exposed to 3D-printed WE43 extracts produced more lactate dehydrogenase (LDH) than those exposed to extruded WE43, suggesting faster cell proliferation. This study demonstrates the importance of hatch distance in the PBF-LB processing of WE43, as well as its potential in balancing corrosion and tensile properties while maintaining a good in vitro cellular response of bone resident cells.
