Regulating mechanical properties and degradation behavior of biodegradable Zn–0.6Mg alloy via ECAP plus cold rolling.

Binary Zn–Mg alloys have great potential as biodegradable implants due to their good biological safety and moderate degradation rates. Herein, a new combined process of ECAP plus cold rolling of as-cast Zn–0.6Mg alloy was developed to address its application problem of insufficient mechanical properties and serious localized corrosion. Cold rolling process can break the eutectic phase and refine grains, while deformed grains were dominant with a lot of dislocations. 8-pass ECAP process can refine grains by recrystallization, and the grains were equiaxed with less dislocations. The strength and ductility were greatly improved after cold rolling (CR) or ECAP processing compared with that of as-cast alloy, but the strength still cannot meet the requirement of orthopedic implant materials. After 8-pass ECAP+CR75% (ER) processing, the strength was further improved, which benefited from fine grain strengthening, second phase strengthening, and strain strengthening mechanisms. Tensile yield strength (σ YS), ultimate tensile strength (σ UTS), and fractured elongation of ER alloy were 301.2 MPa, 411.8 MPa, and 28.5%, respectively, which can meet the requirement of orthopedic implants. The eutectic phase fragmentation and grain refinement caused by cold rolling and ECAP process can reduce the galvanic corrosion tendency of the Zn–0.6Mg alloy. The corrosion resistance was further improved after 8-pass ECAP+CR75% processing with the degradation rate of 0.025 mm/y, and the alloy tended to corrode uniformly. • A new combined process of ECAP plus cold rolling (CR) of as-cast Zn-0.6Mg alloy was developed. • 8-pass ECAP+CR75% processing can refine grains and break eutectic phase of Zn-0.6Mg alloy greatly. • The mechanical properties of 8-pass ECAP+CR75% processed Zn-0.6Mg alloy were superior in Zn-Mg alloys. • The 8-pass ECAP+CR75% processed Zn-0.6Mg alloy tended to corrode uniformly. [ABSTRACT FROM AUTHOR]