挤压温度对Mg-5.3Gd-2.6Y-1.1Nd-0.3Zr合金的力学性能和耐生物腐蚀性能的影响

在不同温度下对均匀化处理后的Mg-5.3Gd-2.6Y-1.1Nd-0.3Zr(质量分数/%)镁合金进行挤压。利用光学显微镜和拉伸实验对比研究固溶态铸锭、不同挤压温度合金的显微组织和力学性能,采用析氢法、失重法和极化曲线实验综合测试合金在Hank’s人体模拟液中的耐生物腐蚀性能,利用扫描电子显微镜观察腐蚀后合金的表面腐蚀形貌。结果表明:随着挤压温度的降低,合金的晶粒不断细化,强度及塑性不断提高,其中390℃温度下挤压得到的合金屈服强度达到223.4MPa,较固溶态铸锭(139.8MPa)提升约60%,且挤压后的合金在Hank’s体液中具有更高的耐腐蚀性,随着挤压温度的降低,合金的耐蚀性先升高后降低,450℃挤压的棒材耐生物腐蚀性能最优,腐蚀速率为0.74mm/a。

Effect of extrusion temperature on mechanical properties and biological corrosion resistance of Mg-5.3Gd-2.6Y-1.1Nd-0.3Zr alloy

The homogenized Mg-5.3Gd-2.6Y-1.1Nd-0.3Zr(mass fraction/%)ingots were extruded at different temperatures.The microstructures and mechanical properties of the solution-treated ingot and those extruded at different temperatures were investigated by optical microscopy(OM)and tensile test.The corrosion resistance of the alloys in Hank’s solutions was evaluated by mass loss,hydrogen evolution and Tafel polarization tests.The surface corrosion morphology of the specimens after immersion was examined by scanning electron microscopy.The results show that the grains of the investigated alloy are refined substantially after extrusion,and their strength and ductility increase along with the decrease of the extrusion temperature,and the yield strength of the extruded alloy under 450℃reaches 223.4MPa,which is about 60%higher than that of T4 alloy(139.8MPa).The extrusion deformation also has positive effects on the alloys’corrosion resistance,and corrosion resistance of the alloy increases first and then decreases along with the decrease of the extrusion temperature.The one extruded under 450℃seems to show the best corrosion resistance,whose corrosion rate is 0.74mm/a.