医用可降解Mg-2Y-1Zn-x Zr合金微观组织和耐蚀性能研究

Microstructure and Corrosion Resistance of Medical Degradable Mg-2Y-1Zn-x Zr Alloy

为了提高医用可降解Mg-2Y-1Zn合金耐腐蚀性能,添加了不同含量的Zr(0,0.2%,0.4%和0.6%,质量分数),并通过XRD、OM、SEM、EDS、析氢和电化学实验等方法研究了Zr含量对合金显微组织和腐蚀行为的影响。结果表明:Mg-2Y-1Zn主要由α-Mg与Mg_(3)Y_(2)Zn_(3)相组成,适量Zr(≤0.4%)的加入没有改变第二相的类型。Zr可以有效细化合金晶粒,优化组织结构,降低腐蚀电流密度,提升合金耐腐蚀性,并使之趋于均匀腐蚀。但当Zr含量达到0.6%时,多余的Zr会析出形成富Zr区,促进电偶腐蚀的发生,使合金耐蚀性有所下降。析氢结果表明,Mg-2Y-1Zn-0.4Zr合金耐腐蚀性最佳。

The effect of Zr addition of 0%, 0.2%, 0.4% and 0.6%(mass fraction) respectively on the microstructure and corrosion behavior in simulated body fluid of Mg-2 Y-1 Zn alloys is systematically investigated via XRD, OM, SEM and EDS, as well as hydrogen evolution measurement and electrochemical measurement. The results show that Mg-2 Y-1 Zn is mainly composed of α-Mg and Mg_(3)Y_(2)Zn_(3) phases, and the addition of Zr(≤0.4%) does not change the type of the second phase, while Zr can effectively refine the grains, optimize the microstructure, slower the corrosion current density, improve the corrosion resistance of the alloy, and make the alloy tend to uniform corrosion. However, when the addition of Zr is0.6%, the excess Zr will precipitate to form a Zr rich region, which promotes the occurrence of galvanic corrosion and reduces the corrosion resistance of the alloy. The results of hydrogen evolution measurement show that the Mg-2 Y-1 Zn-0.4 Zr alloy has the best corrosion resistance.