Multi-parameter optimization of laser powder bed fusion process for pure Zn-based biodegradable implants

ABSTRACT Zinc-based metals exhibit promising prospects for applications in biodegradable medical implants. Laser powder bed fusion (LPBF) has garnered significant attention owing to its capability to meet the complex structural design requirements of such implants. In this study, the effects of LPBF process parameters on the forming quality, microstructure, and mechanical properties of pure zinc samples are investigated. The combined effects of multiple parameters are considered to optimize the LPBF process for pure zinc, in contrast with previous studies focusing on the impact of individual parameters. Determining the optimal printing parameters of multifactor variables is challenging when relying solely on linear energy density and volumetric energy density; however, in this study, by examining the coupling effects of various parameters, the optimal process parameters for the LPBF of pure zinc are effectively identified to improve forming quality and mechanical properties. Under the optimal process conditions (laser power = 50 W, scanning speed = 500 mm/s, hatch spacing = 50 μm, and layer thickness = 30 μm), the maximum relative density (>97%) is observed with zinc grain refinement and a reduction in texture intensity, which facilitate the formation of a bimodal grain size distribution, thereby resulting in optimal mechanical properties. Additionally, a G60 bionic bone pure-zinc scaffold with excellent biological and mechanical performance is fabricated using the optimal process parameters, laying the foundation for the application of LPBF-based pure zinc scaffolds in biodegradable bone implants.