Modulating Hierarchical Microstructure to Enhance Strength–Ductility Synergy in an Additively Manufactured Zinc‐Magnesium Alloy via Static Magnetic Field

Abstract

Additive manufacturing of zinc‐magnesium (Zn‐Mg) alloys via laser powder bed fusion (LPBF) has gained significant recognition as a promising candidate for bone repair. However, the presence of coarse yet brittle eutectic phases in the fabricated Zn‐Mg alloys tends to induce premature stress concentration and resultant fracture during deformation. This study introduced a static magnetic field (SMF) during LPBF to manipulate the eutectic micro‐region and enhance the strength–ductility synergy of a Zn‐Mg alloy for the first time. The results indicated that applying a vertical SMF with an intensity range of 0.14–0.18 T effectively modulated the hierarchical microstructure, including refined eutectic phases at nanometer‐scale, fully equiaxed grains at submicrometer‐scale, and reduced pore defects at micrometer‐scale. Consequently, compared to their counterpart fabricated without SMF, the elongation and ultimate tensile strength of the SMF‐assisted fabricated Zn‐Mg alloy increased by 7.78 times and 0.12 times, respectively, reaching approximately 3.34% and 255.13 MPa, respectively. This superior strength–ductility synergy primarily resulted from the well‐modulated hierarchical microstructure that served as a sustainable source of ductility through synergistic plastic co‐deformation mechanisms while utilizing prominent grain boundary strengthening and precipitation strengthening effects. These findings provide a microstructure manipulation strategy for effectively plasticizing additively manufactured Zn‐Mg alloys in biomedical applications.