Ga含量对Al-Mg-Ga-Sn合金组织和降解性的影响

Effect of Ga content on microstructure and degradability of Al-Mg-Ga-Sn alloys

摘要:

采用电炉熔炼制备了不同Ga含量的Al-Mg-Ga-Sn合金。通过光学显微镜(OM) 、扫描电镜(SEM)和X射线衍射仪(XRD)对其显微组织的形貌和成分进行了表征；在30℃、40℃、70℃、90℃的纯水中进行降解速率的测定；采用电化学工作站测试了室温电化学性能。结果表明：Al-Mg-Ga-Sn合金在Mg+Sn为定值10wt.%的情况下,Ga含量分别为0 wt.%、4 wt.%、8 wt.%、12 wt.%、16 wt.%时,合金组织均有铝基体相和Mg<sub>2</sub>Sn相,且随着Ga含量的增加合金组织中出现了Ga<sub>5</sub>Mg<sub>2</sub>相。Al-Mg-Ga-Sn合金的降解性特点是主要由铝基体相中点蚀开启,由Mg<sub>2</sub>Sn和Ga<sub>5</sub>Mg<sub>2</sub>化合物相的晶间腐蚀加速；不同Ga含量合金的起始降解温度由固溶于铝基体中的低熔点元素(Ga+Sn)的含量决定；相同Ga含量的合金随温度升高降解速率加快,降解反应动力学遵从阿伦尼乌斯公式。室温电化学分析表明：Al-Mg-Ga-Sn合金随Ga含量增加,腐蚀电位不同程度地负移,腐蚀电流逐渐增大。

Abstract:

Al-Mg-Ga-Sn alloys with different Ga contents were prepared by electric furnace melting. Their microstructure morphology and compositions were characterized by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffractometry (XRD); their degradation rates were measured in pure water at 30 °C,40 °C, 70° C, and 90° C; and their electrochemical performance at room temperature was tested using the electrochemical workstation. The results revealed that in case that Mg+Sn is 10 wt.%, Al-Mg-Ga-Sn alloys with 0 wt.%, 4 wt.%, 8 wt.%, 12 wt.%, and 16 wt.% Ga, respectively, all contain Al matrix phase and Mg<sub>2</sub>Sn phase. Moreover, Ga<sub>5</sub>Mg<sub>2</sub> phase appears with the increase in Ga content. The degradability of Al-Mg-Ga-Sn alloys primarily present start-up with pitting corrosion in aluminum matrix phase, and acceleration with intergranular corrosion between Mg<sub>2</sub>Sn and Ga<sub>5</sub>Mg<sub>2</sub> compound phases. The initial degradation temperatures of alloys with different Ga content depend on the content of low melting point elements (Ga+Sn) solved in the aluminum matrix; the alloy with the same Ga content rapidly degrade with elevating temperature, and the degradation reaction kinetics follows Arrhenius. Uz formula. Electrochemical analysis at room temperature indicated that as Ga content raises in Al-Mg-Ga-Sn alloy, the corresponding corrosion potential negatively shifts to different extent, while the corrosion current gradually improves.