Microstructural evolution, synergistic strengthening mechanisms, and initial biological evaluation of Zn–5Y alloy fabricated by laser powder bed fusion

Abstract Zn alloys are promising biomedical materials for use in applications such as urethral stents and cardiovascular stents; however, pure Zn suffers from inadequate mechanical strength. In this study, a novel Zn-5 wt.% Y alloy was successfully fabricated using laser powder bed fusion. The effect of Y addition on the microstructure, mechanical properties, antibacterial activity, and cytocompatibility was systematically investigated. Results showed that the incorporation of Y induced a profound grain refinement effect, reducing the average grain size from 14.6 μ m to 3.8 μ m (a 74% reduction), and transformed the strong basal texture of pure Zn into a near-random orientation. Consequently, the ultimate tensile strength increased significantly from 112.4 MPa to 147.1 MPa, attributed to a synergistic effect of grain boundary and second-phase. Furthermore, the Zn-–5Y alloy exhibited enhanced antibacterial activity. In vitro cytocompatibility assays using HEK-293 T cells demonstrated that the 25% extract of the alloy was non-toxic (Grade 0–1) and promoted superior cell adhesion and spreading compared to pure Zn. This study provides a metallurgical basis for developing high-strength Zn-rare-earth element systems via additive manufacturing.