轧制方式对镁合金生体腐蚀行为的影响

采用光学显微镜、扫描电镜、浸泡质量损失和拉伸测试等手段研究了轧制方式(常规轧制和一道次高应变速率轧制)对镁合金(纯镁,Mg-4Zn,Mg-4Zn-0.3Ca和ZK60)在Hank’s溶液中腐蚀行为的影响.结果表明:与常规轧制态相比,高应变速率轧制态镁合金在长时间浸泡过程中平均腐蚀速率较低,抗拉强度下降幅度较小,耐腐蚀性能明显提高,可归因于晶粒细化、再结晶程度较高、孪晶较少和残余第二相相对粗大等;轧制态合金中第二相较少且较细小,表现为相对均匀的丝状腐蚀.

Effects of Rolling Mode on Bio-corrosion Behavior of Magnesium Alloys

The effects of rolling mode (conventional rolling and high strain-rate rolling in a single pass) on bio-corrosion behavior of magnesium alloys (ZK60, Mg-4Zn-0.3Ca, Mg-4Zn and pure Mg) were investigated by optical microscope (OM), scanning electron microscope (SEM), mass loss of immersion testing and tensile testing. The results showed that magnesium alloy prepared by high strain-rate rolling exhibited lower average corrosion rate and reduced slightly in ultimate tensile strength, compared with the counterpart prepared by conventional rolling. Meanwhile, better corrosion resistance was also exhibited, which could be attributed to the grain refinement, higher DRX extent, fewer twins, and relatively coarse remained second phases. The as-rolled alloys also exhibited a uniform filiform corrosion due to the lower fraction and finer size of the second phase.