Toughness and Strength Coordination in a Low-Alloy Zn-0.5 Mg Alloy via Extrusion and Post-Deformation Annealing

Zn is considered one of the most attractive bioresorbable candidates for metal implants, because it does not exhibit the inherent limitations of Fe and Mg. To explore the coordination of the toughness and strength of Zn alloys via grain size, secondary phase, and texture modification, we designed a micro-alloyed binary Zn-0.5 Mg (wt%) alloy. The sample was processed through hot extrusion at 220 degrees C with an extrusion ratio of 25:1 and subjected to rapid heat treatment at varying temperatures. Interestingly, the ductility of the low-temperature annealed alloys increased without exhibiting strength loss, in contrast to the known behavior of most other metallic alloys. The mechanical properties were optimized in the sample by thermal deformation and 30 min annealing at 150 degrees C, exhibiting the following results: yield strength of 240.3 +/- 4.3 MPa, ultimate tensile strength of 293.6 +/- 3.8 MPa, and elongation to failure of 36.3 +/- 4.5%. During the low-temperature annealing of extruded Zn-0.5 Mg rods, the fine Mg2Zn11 phase particles pinning effect and the recrystallization behavior inhibited grain coarsening. The prismatic < a > and pyramidal < c + a > slip systems were activated by a non-basal texture, which contributed to the enhanced toughness. The balance between strength and ductility was mainly attributed to a synergistic effect of grain refinement, unique texture modification, and secondary phases.