热处理对Al-Mg-Ga-In-Sn合金微观结构和铝水反应的影响

Effect of Heat Treatment on Microstructure and Al-water Reactivity of Al-Mg-Ga-In-Sn Alloys

制备不同镁含量的Al-Mg-Ga-In-Sn合金并对其进行固溶和时效热处理,用XRD和SEM分析和观察了显微结构和腐蚀表面,用AFM/SKPFM测量了合金不同晶界相与铝晶粒间的电势差,用排水法测量了在不同水温下合金的铝水反应。结果表明,热处理改变了合金低熔点界面相的种类、形态以及合金晶粒内Mg和Ga含量。热处理态Mg含量低于4%的合金,其中有Mg_(2)Sn、MgGa、MgGa_(2)、MgIn界面相;在Mg含量为5%的热处理态合金中出现了Mg_(5)Ga_(2)、Mg_(2)Ga相。在时效态合金晶粒内有MgGa相析出。与相同成分的铸态合金相比,时效态合金中各晶界相与铝基体间的电位差较大。热处理态合金的产氢速率和产氢率,与合金的Mg含量有关。分析了热处理使合金显微结构和晶界相与铝基体间电位差变化的原因,并讨论了热处理对合金铝水反应的影响。

Al-Mg-Ga-In-Sn alloys with different Mg-contents were prepared and then subjected to solution and aging treatment. The microstructure and corrosion morphology after immersion in water of alloys was characterized by means of XRD and SEM with EDX. The Volta potential differences(ΔVPD) of interfacial phases with respect to Al matrix were measured using AFM/SKPFM. The Al-water reactivity of alloys in waters at different temperature were measured by using drainage method. The heat treatment influences the phase type, morphology of interfacial phases, and the content of Mg and Ga inside Al grains.As the Mg content is below 4% the heat-treated alloys contain interfacial phases of Mg_(2)Sn, MgGa, MgGa_(2) and MgIn. Mg_(5)Ga_(2) and Mg_(2)Ga phases occurs as the Mg content of alloy is c.a. 5%. MgGa phase precipitates within Al grains of the aged alloys. The heat-treated alloys exhibit higher the Volta potential differences(ΔVPD) of interfacial phases with respect to Al in comparison with the cast ones. The generation rate and yield amount of hydrogen correlate with Mg contents of the heat-treated alloys. The reasons that the heat treatment affects the microstructures of alloys and the Volta potential differences(ΔVPD) of interfacial phases with respect to Al were analyzed, and the effect of heat treatment on the Al-water reactivity of alloys was also discussed.