Precipitation behavior of intermetallic compounds and their effect on mechanical properties of thick plate friction stir welded Al/Mg joint
Precipitation behavior of intermetallic compounds and their effect on mechanical properties of thick plate friction stir welded Al/Mg joint
复制标题
金属间化合物析出行为及其对厚板Al/Mg搅拌摩擦焊接头力学性能的影响
DOI：
10.1016/j.jmapro.2020.12.068
复制
发表时间：
2021-03-02
影响因子：
6.2
通讯作者：
Niu, Pengliang
中科院分区：
文献类型：
--
作者：
Xu, Yang;Ke, Liming;Niu, Pengliang
异种材料接头中容易形成脆性金属间化合物，严重影响接头的可靠性。为了避免或控制脆性金属间化合物的产生，设计了20 mm厚度的5A06 Al和AZ31B Mg合金的搅拌摩擦焊倾斜对接接头。通过光学显微镜、扫描电子显微镜、显微X射线衍射、透射电子显微镜研究了接头的显微组织和化学成分。焊核区金属间化合物沿厚度方向呈现出不同的析出行为。在焊核区上部，由于焊核区上部温度过高，在凝固过程中析出金属间化合物Al3Mg2、Al12Mg17和非平衡相AlMg。 Al3Mg2相仅在焊核区中下部沿晶界析出、长大。最大维氏硬度值约为289 HV，该值出现在Mg侧界面的上部，存在由Mg和Al12Mg17组成的厚共晶区。 Al12Mg17层和Al3Mg2层的纳米硬度分别为5.39 GPa和4.18 GPa。 Al12Mg17相和Al3Mg2相的析出起到析出强化作用。
Brittle intermetallic compounds are prone to form in dissimilar joints, which significantly affected the reliability of the joints. To avoid or control the production of brittle intermetallic compounds, an inclined butt joint of 5A06 Al and AZ31B Mg alloys with 20 mm thickness using friction stir welding was designed. Microstructures and chemical composition of the joint were investigated by optical microscopy, scanning electron microscopy, micro X-ray diffraction, transmission electron microscopy. The intermetallic compounds in the weld nugget zone presented different precipitation behavior along the thickness direction. In the upper of the weld nugget zone, intermetallic compounds Al3Mg2, Al12Mg17, and non-equilibrium phase AlMg precipitated during solidification due to excessively high temperature of the upper of the weld nugget zone. The Al3Mg2 phase merely precipitated and grown along the grain boundaries in the middle and lower of the weld nugget zone. The maximum Vickers hardness value was approximately 289 HV, which was obtained at the upper of the Mg side interface, existing a thick eutectic zone consisted of Mg and Al12Mg17. The nanohardness of the Al12Mg17 layer and the Al3Mg2 layer were 5.39 GPa and 4.18 GPa, respectively. The precipitation of the Al12Mg17 and the Al3Mg2 phases plays a precipitation strengthening effect.