挤压态低合金化Mg-0.5Bi-0.5Y-0.2Zn合金的腐蚀行为及力学性能

Corrosion behavior and mechanical properties of extruded low-alloyed Mg−0.5Bi−0.5Y−0.2Zn alloy

研发一种新型低合金化Mg-Bi-Y-Zn合金系,该合金系在673 K的挤压温度下成功成型。通过扫描电子显微镜(SEM)、电子背散射衍射(EBSD)、电化学试验和拉伸试验研究挤压态合金的腐蚀行为和拉伸性能。挤压后,合金表现出几乎完全的动态再结晶组织和典型的挤压织构,在晶粒内可以观察到一些亚微米级析出相。在SBF溶液中,合金的腐蚀模式由最初的点蚀为主转变为中间过程的丝状腐蚀为主;最后经长时间浸泡后,腐蚀模式转变为丝状腐蚀和局部晶粒脱落。挤压态Mg-0.5Bi-0.5Y-0.2Zn合金的屈服强度为237 MPa,极限抗拉强度为304 MPa,伸长率为31%,平均腐蚀速率为0.14 mm/a。由此可见,该合金表现出良好的拉伸性能和耐腐蚀性能匹配度,这主要归因于其均匀的晶粒结构和亚微米级析出相。因此本文所研发的Mg-0.5Bi-0.5Y-0.2Zn合金具有在生物医药领域的广阔应用前景。

A novel low-alloyed Mg−Bi−Y−Zn alloy system was developed and extruded successfully at 673 K.The corrosion behavior and tensile properties of the extruded alloy were investigated through scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),electrochemical tests and tensile test.The extruded alloy exhibits a nearly fully recrystallized grain structure with a scattered extrusion fiber texture and some sub-micron precipitates.In SBF solution,the dominated corrosion mode changed from galvanic induced pitting corrosion at initial stage to filiform-like corrosion and finally mixed pitting corrosion and local fall-off of grains during long-term corrosion processes.The tensile properties and corrosion resistance of the extruded Mg−0.5Bi−0.5Y−0.2Zn(wt.%)alloy are:tensile yield strength of 237 MPa,ultimate tensile strength of 304 MPa,elongation to failure of 31%and mean corrosion rate of 0.14 mm/a.The great balance between tensile properties and corrosion resistance is mainly attributed to the homogeneous grain structure and the presence of sub-micron scaled precipitates,indicating a promising potential in the application in biomedical field.