6061铝合金的等温凝固组织及第二相的析出顺序

Isothermal Solidification Microstructure and Second Phases Precipitation Sequence of the 6061 Aluminum Alloy

制备了不同等温温度时6061铝合金凝固试样,利用扫描电镜观察了试样的微观组织,利用能谱分析仪测试了等温凝固组织中相的成分,利用X射线衍射仪测试了等温凝固试样中的相组成。结果表明,6061铝合金从900~650℃等温凝固时相的析出顺序为:L→α-Al+Al4Cu9+CrMn3+Cu16Mg6Si7+Mn5Si3→Cr3Si→Cu2Mg→FeCr+Cu16Mg6Si→富Fe相→Al7Cu3Mg6+Mg2Si+α-AlFeSi;6061铝合金常见的有害富Fe相是在温度低于700℃时形成的;6061铝合金等温凝固时析出的第二相主要聚集在晶界处。

The isothermal solidification samples of 6061 aluminum alloy at different temperatures were prepared. The isothermal solidification microstructure of the samples was observed by metallographic microscope, and the composition of different phases in the isothermal solidification structure was measured by SEM and EDS, and the types of different phases in the isothermal solidification samples were measured by X-ray diffractometer. The results show that the precipitation sequence of 6061 aluminum alloy during solidification is presented as follows: L→α-Al+Al4Cu9+CrMn3+Cu16Mg6Si7+Mn5Si3→Cr3Si→Cu2Mg→FeCr+Cu16Mg6Si→iron-rich phase→Al7Cu3Mg6+Mg2Si+α-AlFeSi. The harmful iron-rich phase in 6061 aluminum alloy during application is generated when the temperature is lower than 700 ℃. The second phase precipitated during solidification is mainly segregated at the grain boundary.