固溶处理Mg-0.5Zr-1.8Zn-xGd生物可降解镁合金的微观组织、力学性能和腐蚀性能

Microstructures, Mechanical Properties and Corrosion Behavior of Solution-Treated Mg-0.5Zr-1.8Zn-xGd Biodegradable Alloys

研究了Mg-0.5Zr-1.8Zn-x Gd (x=0,0.5,1.0,1.5,2.0,2.5,质量分数,%)镁合金经过470℃和10 h固溶处理后的组织、力学性能和耐腐蚀性能。结果表明,Gd含量在0%-2.5%范围内,随着Gd含量增加,合金晶粒尺寸逐渐减小。当Gd含量低于1.5%时,合金元素几乎完全固溶于合金基体中,第二相主要由纳米尺度的(Mg,Zn)3Gd析出颗粒组成。当Gd含量在1.5%-2.5%范围时,合金中出现未固溶的微米尺度的(Mg,Zn)3Gd相,并且该相数量和尺寸随着Gd含量增加而增加。由于组织均匀分布和纳米尺寸的第二相颗粒存在,Mg-0.5Zr-1.8Zn-1.5Gd合金具有优异的力学性能和耐腐蚀性能。在120 h浸泡实验中,Mg-0.5Zr-1.8Zn-1.5Gd合金平均腐蚀速率首先降低,然后增加,接着缓慢降低,最后,随着浸泡时间延长,腐蚀速率最终变得稳定。

The microstructure, mechanical and anticorrosion properties of Mg-0.5 Zr-1.8 Zn-x Gd(x=0, 0.5, 1.0, 1.5, 2.0, 2.5, wt%)alloys were investigated after a solution treatment at 470 ℃ for 10 h. Results indicate that the grain size of the alloy decreases with increasing the Gd content in the range of 0 wt% -2.5 wt%. When the Gd content is less than 1.5 wt%, the alloy elements are more completely dissolved into the alloy matrix, and the second phase is mainly composed of nanoscale(Mg, Zn)3 Gd precipitated particle.At the range of 1.5 wt%-2.5 wt%, the insoluble micron-scale(Mg, Zn)3 Gd phase emerges in the alloy, and the number and size of the(Mg, Zn)3 Gd phase increase with the Gd content. The Mg-0.5 Zr-1.8 Zn-1.5 Gd alloy shows excellent mechanical properties and anticorrosive ability, which can be attributed to a more homogeneous microstructure and the presence of nanometric secondary phase particles. In the 120 h immersion experiment, the average corrosion rate of the Mg-0.5 Zr-1.8 Zn-1.5 Gd alloy deceases at first, then increases, and then decreases slowly. At last, with the increase of immersion time, it eventually becomes stable.