Gui Zhenzhen, Zhang Junyi, Kang Zhixin
School of Mechanical and Electrical Engineering, Guangzhou University, 230 Wai Huan Xi Road, Guangzhou Higher Education Mega Center, Guangzhou 510006, China.
Guangdong Key Laboratory for Advanced Metallic Materials Processing, School of Mechanical & Automotive Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640, China.
Materials (Basel). 2020 Mar 20;13(6):1421. doi: 10.3390/ma13061421.
The differences in microstructural characteristics, mechanical properties, and corrosion behavior of the as-cast and solution-treated Mg-xGd-1.5Nd-0.5Zn-0.5Zr alloys (Mg-xGd, x = 1, 3, and 5) were studied and discussed. The as-cast Mg-xGd alloys mainly consisted of an α-Mg and island-like eutectic (Mg,Zn)RE phase, a few cuboidal phases (REH), and a ZnZr phase. With the increase of Gd content, the grain sizes of the as-cast Mg-xGd alloys decreased. Compared to the microstructure of the as-cast Mg-xGd alloys, the eutectic (Mg,Zn)RE phase disappeared and the cuboidal REH phases existed in the solution-treated Mg-xGd alloys. A large amount of ZnZr phase was precipitated from α-Mg in the Mg-3Gd alloy and demonstrates a flower-like distribution. The ultimate tensile strength (UTS) and yield strength (YS) of the solution-treated Mg-xGd alloys increased with an increasing Gd content, with the UTS and YS of the Mg-5Gd alloys reaching 217.5 and 125.2 MPa, respectively. Immersion and electrochemical tests showed that the as-cast Mg-3Gd alloy presented the best corrosion resistance with a corrosion rate of 0.285 mm/yr. The corrosion resistance of the solution-treated Mg-3Gd alloy attained the lowest value (0.973 mm/yr), due to the large quantities of ZnZr with a flower-like phase distribution, forming series of galvanic couple groups with the α-Mg.
研究并讨论了铸态及固溶处理后的Mg-xGd-1.5Nd-0.5Zn-0.5Zr合金（Mg-xGd，x = 1、3和5）在微观结构特征、力学性能和腐蚀行为方面的差异。铸态Mg-xGd合金主要由α-Mg和岛状共晶（Mg,Zn）RE相、少量立方相（REH）以及ZnZr相组成。随着Gd含量的增加，铸态Mg-xGd合金的晶粒尺寸减小。与铸态Mg-xGd合金的微观结构相比，固溶处理后的Mg-xGd合金中共晶（Mg,Zn）RE相消失，存在立方REH相。在Mg-3Gd合金中，大量的ZnZr相从α-Mg中析出，并呈现出花状分布。固溶处理后的Mg-xGd合金的抗拉强度（UTS）和屈服强度（YS）随着Gd含量的增加而提高，Mg-5Gd合金的UTS和YS分别达到217.5和125.2 MPa。浸泡和电化学测试表明，铸态Mg-3Gd合金具有最佳的耐腐蚀性，腐蚀速率为0.285 mm/年。固溶处理后的Mg-3Gd合金的耐腐蚀性达到最低值（0.973 mm/年），这是由于大量呈花状相分布的ZnZr相与α-Mg形成了一系列电偶组。
