Effect of a bimodal grain structure on corrosion behavior and tensile properties of low-alloyed Mg–1Bi–1Zn–1Ag alloy

A novel low-alloyed Mg–1Bi–1Zn–1Ag alloy system was developed by extrusion at different extrusion ratios to achieve a bimodal grain structure. The dependence of the corrosion behavior and tensile properties on the grain structure was analyzed. The sample obtained at the extrusion ratio of 9 (BZQ111-R9) displayed a bimodal grain microstructure. In addition, its dominant corrosion mode was filiform with intergranular corrosion at a low corrosion rate of 0.06 mm/a. An improved synergy between strength (tensile yield strength of 207.1 MPa) and ductility (elongation of 35.9%) was realized in the BZQ111-R9 sample. Thus, the proposed approach can develop low-alloyed Mg–Bi-based alloys with excellent synergy between the corrosion resistance and tensile properties based on the control of the bimodal grain structure.