Additive manufacturing of high porosity magnesium scaffolds with lattice structure and random structure

Although additive manufactured Magnesium alloys with high porosity are in great demand for structural and biomedical applications due to outstanding mechanical properties and biocompatibility, parametric design and control of 3D printed Mg alloys with complex structures have rarely been studied. In the present work, two parametric frames, a newly hybrid three period minimal surface (TPMS) cellular structure and a Voronoi structure, are designed with high porosity ranging from 83% to 95% and fabricated by means of SLM using Mg alloy powders. The printing quality and the printing accuracy of all specimens are evaluated by SEM and GOM inspect suite 2020 respectively, and the mechanical properties are measured from the corresponding stress-strain responses under quasi-static compression test. Complementary, static 3D models are developed to simulate and analyze the mechanical properties of both structures using the finite element method. Experimental results show that all 3D printed specimens are identified with continuous connections and interconnected porous architectures, and the average deviations between designed models and printed specimens are within 5%. Meanwhile, the properties of both parametric structures are porosity dependent, and elastic moduli of 3D printed specimens are within the range of cancellous bones and can be adjusted easily through the design parameters. With such high porosity, both structures show low density in the range of 0.09 g/cm3 to 0.31 g/cm3 as well as high hardness around 100 HV. Meanwhile, hybrid TPMS structures display superior mechanical properties compared to Voronoi structures, which is mainly ascribed to the unique structure revealed from the simulation results. In summary, this study provides a new reference for the parametric design of additive manufactured Mg alloys with porous structures for potential biomedical applications.