热处理对Bi微合金化Al-Ga-Mg-Sn合金组织和降解性的影响

Effect of Heat Treatment on Microstructure and Degradation Properties of Bi Microalloyed Al-Ga-Mg-Sn Aluminum Alloy

摘要:

对铸态 Al-Ga-Mg-Sn 可降解铝合金进行微合金化和热处理。选取Al-Ga-Mg-Sn-Bi合金进行退火热处理和固溶/时效处理。采用光学显微镜、扫描电子显微镜、X 射线衍射仪和电化学工作站测试分析 Al-Ga-Mg-Sn-Bi 合金的组织、相组成和自腐蚀电位。结果表明：微量Bi、Zn元素的添加可降低Al-Ga-Mg-Sn自腐蚀电位；铸态 Al-Ga-Mg-Sn-Bi 合金由 Al 基体相、Mg₂Sn 和 Mg-Ga 相组成，鱼骨状树枝晶特征明显；室温下、3wt% KCl溶液中的自腐蚀电位介于–1.60~–1.49 V。随退火温度的升高，树枝晶减少并于500 ℃ 消失；固溶/时效处理后析出Mg₂Sn 和 Mg-Ga相。与铸态 Al-Ga-Mg-Sn-Bi 合金硬度相比，退火处理后硬度降低；固溶/时效处理后硬度提升。与铸态 Al-Ga-Mg-Sn-Bi 合金降解速率相比，固溶/时效处理和退火热处理均降低降解速率。

Abstract:

The as-cast Al-Ga-Mg-Sn degradable aluminum alloy was microalloyed and heat treated. Al-Ga-Mg-Sn-Bi alloy was selected for annealing and solid solution/aging treatment. The microstructure, phase composition and self-corrosion potential of Al-Ga-Mg-Sn-Bi alloy were analyzed by optical microscope, scanning electron microscope, X-ray diffractometer and electrochemical workstation. The results show that the addition of trace elements Bi and Zn reduces the self-corrosion potential of Al-Ga-Mg-Sn. The as-cast Al-Ga-Mg-Sn-Bi alloy is composed of Al matrix phase, Mg₂Sn and Mg-Ga phase, and the characteristics of fishbone dendrites are obvious at room temperature, the self-corrosion potential in 3wt% KCl solution ranges from –1.60 V to –1.49 V. With the increase in annealing temperature, dendrites decrease, and disappear at 500 ℃. Mg₂Sn and Mg-Ga phases are precipitated after solid-solution/aging treatment. Compared with as-cast Al-Ga-Mg-Sn-Bi alloy, the hardness of alloy after annealing treatment decreases. Whereas, hardness of alloy after solution/aging treatment increases. Compared with as-cast Al-Ga-Mg-Sn-Bi alloy, the degradation rates of alloy after both solution/aging treatment and annealing treatment reduce.