时效处理对Mg-2.0Zn-0.5Zr-3.0Gd生物降解镁合金组织、力学性能及耐腐蚀性能的影响

通过金相显微分析(OM)、扫描电镜观察(SEM)、透射电镜观察(TEM)和拉伸性能测试研究不同时效时间对Mg-2.0Zn-0.5Zr-3.0Gd生物镁合金显微组织及力学性能的影响,通过质量损失和电化学方法研究合金在模拟体液(SBF)中的耐腐蚀性能。结果表明:时效时间为4~20 h时,合金中析出相的尺寸及数量随时效时间的延长而增加,析出相主要以纳米级棒状和颗粒状的(Mg,Zn)3Gd相形式存在,部分棒状析出相与α-Mg基体具有共格界面关系。合金的强度及伸长率随时效时间的延长先升高后降低。在120 h的浸泡实验中,合金的平均腐蚀速率、点蚀孔洞的数量及孔洞尺寸随时效时间的延长而逐渐增大,腐蚀速率随浸泡时间延长呈现出先减小、后增大、再缓慢减小以及最后趋于稳定的过程。

Effects of aging treatment on microstructure,mechanical properties and corrosion resistance of biodegradable Mg-2.0Zn-0.5Zr-3.0Gd magnesium alloy

The effects of aging time on the microstructure and mechanical properties of Mg-2.0Zn-0.5Zr-3.0Gd biomedical magnesium alloy were investigated by optical microscope(OM),scanning electron microscope(SEM),transmission electron microscope(TEM)and tensile properties tests.The results show that the size and quantity of precipitated phases in the alloy increase with the increase of aging time at range of 4-20 h.The precipitated phases are mainly in the form of nano-sized rod-like and granular(Mg,Zn)3Gd phase.While partially rod-like precipitated phase has coherent interface relationship withα-Mg matrix.The strength and elongation of the alloy gradually increase with the increasing of the aging time,and then decrease.In the 120 h immersion experiment,the average corrosion rates,number and size of corrosion holes in the alloy increased with increase of the aging time.The corrosion rate decreases at first,then increase,and then decrease slowly.At last,it tends to be stable with the increase of immersion time.