均匀化退火对Mg-3Al-1Zn-2.2/5Sr镁合金中第二相的影响

Effect of Homogenization Annealing on Second Phases in Mg-3Al-1Zn-2.2/5Sr Magnesium Alloys

摘要:

为研究均匀化退火处理对Mg-3Al-1Zn-2.2/5Sr镁合金中第二相的影响，通过X射线衍射分析（XRD）、扫描电镜观察（SEM）和能谱分析（EDS）等手段，并结合Pandat热力学计算软件，对Mg-3Al-1Zn-2.2/5Sr镁合金均匀化退火后组织中的第二相的类型及形成原因进行了分析。结果表明：经过400 ℃, 15 h（炉冷）的均匀化退火处理以后，合金铸态组织中原本存在的(Mg,Al)17Sr2相中固溶的Al元素所占原子分数有所降低。此外，Sr含量为2.2%(质量分数)的合金组织中可以观察到大量沿(Mg,Al)17Sr2相边缘分布的颗粒状Al4Sr相，而Sr含量为5%的合金中基本观察不到(Mg,Al)17Sr2相的变化

Abstract:

In order to investigate the effect of homogenization annealing on the second phases of Mg-3Al-1Zn-2.2/5Sr magnesium alloys, the type and formation theory of second phases in the as-annealed Mg-3Al-1Zn-2.2/5Sr alloys were investigated by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD) combined with Pandat thermodynamic calculation software. The results indicate that after homogenization annealing at 400 oC for 15 h and cooling in furnace, the fraction volume of Al in (Mg, Al)17Sr2 phase preliminarily formed in the as-cast structure of Mg-3Al-1Zn-2.2/5Sr alloys decreases slightly. In addition, a huge number of granular Al4Sr phases are formed along the edge of the (Mg, Al)17Sr2 phase in Mg-3Al-1Zn-2.2Sr alloy, while the change of (Mg, Al)17Sr2 is hardly to be observed in the microstructure of the alloy with 5% Sr addition.