挤压温度对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

Effect of extrusion temperature on microstructure, mechanical properties and corrosion resistance of biodegradable Mg-2.0Zn-0.5Zr-3.0Gd magnesium alloy

研究挤压温度对铸态Mg-2.0Zn-0.5Zr-3.0Gd生物镁合金组织、力学性能及耐腐蚀性能的影响。结果表明:挤压温度在330～350℃时,动态再结晶的体积分数随挤压温度的升高而增加;在350～370℃时,动态再结晶的体积分数随温度的升高而降低。挤压态合金的析出相主要由纳米级的棒状(Mg, Zn)_3Gd相和新析出的颗粒状Mg_2Zn_(11)相组成。合金的力学性能与动态再结晶晶粒的体积分数成正比关系。挤压温度为350℃时,合金的抗拉强度、屈服强度及伸长率分别为(247±3) MPa、(214±3) MPa和(26.7±1.1)%。随着挤压温度的升高,合金的腐蚀速率先减小后增大,挤压温度为350℃时,合金的静态腐蚀速率及析氢腐蚀速率分别为0.614 mm/a和0.598 mm/a。

Effects of the extrusion temperature on the microstructure,mechanical properties and corrosion resistance of as-cast Mg-2.0Zn-0.5Zr-3.0Gd biomedical magnesium alloy were investigated.The experimental results show that the volume fraction of dynamic recrystallized(DRXed)microstructure increases with increasing the extrusion temperature from 330℃to 350℃,but decreases as the temperature increased further to 370℃.The precipitated phases of extruded alloys are composed of nanoscale rod-like(Mg,Zn)3Gd and granular Mg2Zn11 phase.The Mg2Zn11 precipitated phase is a new precipitated phase in the extrusion process.The mechanical properties of extruded alloys are proportional to the volume area fraction of the DRXed grains.When the extrusion temperature is 350℃,the ultimate tensile strength,yield strength and ultimate tensile strength of extruded alloys are(248±3)MPa,(228±3)MPa and(29.4±0.9)%,respectively.The corrosion rates of the extruded alloys decrease initially and then increase with increasing the extrusion temperature from 330℃to 370℃.The corrosion rates of the alloy were determined to be 0.614 mm/a and 598 mm/a,respectively,in mass loss and hydrogen evolution methods when the extrusion temperature is 350℃.