Achieving quadruple performance enhancement in biodegradable Zn‐Fe alloys via accumulative cooling and interface fusion (ACIF)

Abstract Theoretically, cooling rate decreases exponentially as solidification thickness increases. This leads to coarse second‐phase particles in Zn alloys, which not only impairs mechanical properties but also exacerbates degradation nonuniformity. To address this common issue, we have developed accumulative‐cooling and interface‐fusion (ACIF) technology that maintains a high cooling rate regardless of increased solidification thickness. Using Zn‐0.4Fe as a model alloy, the accumulative‐cooling process achieves an average cooling rate of 817 °C min −1 , approximately 68 times that of air cooling. After extrusion, the average size of FeZn 13 particles is refined from 29.4 to 0.4 μm, reaching the highest level of refinement in Zn alloys. As a result, a quadruple enhancement of Zn‐0.4Fe model alloy has been achieved: Ultimate tensile strength enhanced 1.6‐fold to 265 MPa (the highest among Zn‐Fe alloys), elongation enhanced from 29% to 48%, corrosion uniformity improved 3 times, and cell viability of mouse embryonic osteoblast precursor cells (MC3T3‐E1) increased by 20%. A long rod is obtained via ACIF, overcoming the limitation that fast‐cooled Zn alloys could only be produced in thin plate form. This enables the possibility of fabricating bone screws and vascular stents using bulk Zn alloys with fine second‐phase particles. From a technical standpoint, this technique can be widely applied to a variety of metallic materials.