锶对挤压态二元锌锶合金显微组织、力学性能及体外降解行为的影响

Effects of Sr addition on microstructure, mechanical properties and in vitro degradation behavior of as-extruded Zn-Sr binary alloys

系统研究纯锌和Zn-x Sr(x=0.1%,0.4%,0.8%,质量分数)合金热挤压后的显微组织、力学性能及体外降解行为。研究发现:添加0.1%Sr后合金中析出Sr Zn13相,使挤压后合金的屈服强度、抗拉强度及伸长率由纯锌的(85.33±2.86)MPa、(106.00±1.41)MPa和(15.37±0.57)%分别提高到(107.67±2.05)MPa、(115.67±2.52)MPa和(20.80±2.19)%;继续增加Sr含量,由于析出粗大的Sr Zn13相,容易引用应力集中和裂纹产生,使合金的性能下降。此外,分布不均匀的Sr Zn13相与基体之间存在的微电偶腐蚀作用使得添加Sr后合金的体外降解速度加快,同时,降解变得不均匀。随着Sr含量的增加,降解速度逐渐加快,由纯锌的(11.45±2.02)mm/a逐渐增加至Zn-0.8Sr的(32.59±3.40)mm/a。其中,挤压态Zn-0.1Sr合金具有最佳的综合力学性能与降解性能。

The microstructures,mechanical properties and in vitro degradation behavior of as-extruded pure Zn and Zn-x Sr(x=0.1,0.4,0.8 wt.%)alloys were investigated systematically.For the microstructure and mechanical properties,Sr Zn13 phase was newly formed due to the addition of 0.1 wt.%Sr,improving the yield strength,ultimate tensile strength and elongation from(85.33±2.86)MPa,(106.00±1.41)MPa and(15.37±0.57)%for pure Zn to(107.67±2.05)MPa,(115.67±2.52)MPa and(20.80±2.19)%for Zn-0.1Sr,respectively.However,further increase of Sr content led to the deterioration of the mechanical properties due to the stress concentration and cracks initiation caused by the coarsening Sr Zn13 particles during tensile tests.For in vitro degradation,since micro galvanic corrosion was enhanced owing to the formation of the inhomogeneously distributed Sr Zn13 phase,the corrosion mode became non-uniform.Corrosion rate is gradually increased with the addition of Sr,which is increased from(11.45±2.02)μm/a(a=year)for pure Zn to(32.59±3.40)μm/a for Zn-0.8Sr.To sum up,the as-extruded Zn-0.1Sr alloy exhibited the best combination of mechanical properties and degradation behavior.