Simultaneously improve mechanical properties and osteogenic properties of biodegradable Zn alloys by refining grain sizes to sub-micrometers

Precise modulation of degradation behavior is vital for the biomedical use of biodegradable zinc-based alloys. Variations in electrochemical potential between the Zn matrix and secondary phases markedly influence both the mechanical performance and corrosion characteristics of these alloys. In this work, a zinc alloy with an ultrafine-grained (UFG) structure was fabricated through a two-step rolling process, refining the grain size from 17.28 μm to 0.41 μm (a percentage reduction of 98%). The resulting material exhibited outstanding mechanical strength and ductility, achieving values of 383 MPa in tensile strength and 114% in elongation at ambient temperature. Microstructural analysis revealed uniformly refined grains accompanied by CuZn5 particles (~ 300 nm) and nanoscale precipitates. The enhanced mechanical properties mainly stem from grain-boundary, dislocation, and precipitation strengthening mechanisms. Compared with coarse-grained pure zinc, the UFG alloy displayed more homogeneous corrosion in Hank's solution. Furthermore, in vitro assays demonstrated favorable cytocompatibility and osteogenic potential. Collectively, these findings suggest that the UFG Zn alloy holds promise as a next-generation biodegradable metal with exceptional ductility, controlled corrosion performance, and excellent biocompatibility for orthopedic implant applications.