均匀化退火对7050/6009复层板坯组织、成分和力学性能的影响

摘要

研究均匀化退火对直接冷却法制备的7050/6009复层板坯界面区域的组织演化、成分分布和力学性能的影响。结果表明，最佳的均匀化退火工艺是460°C条件下保温24 h。均匀化退火后，在复层板坯界面处沉淀出了富锌相和Al15(FeMn)3Si2相。均匀化时间固定为24 h的条件下，当均匀化温度由440°C增加到480°C时，复层试样的扩散层厚度增加了30μm；均匀化温度固定为460°C条件下，当均匀化时间由12 h增加到36 h时，复层试样的扩散层厚度增加了280μm。均匀化退火后，复层合金的6009合金侧和界面处的维式硬度均降低，晶粒粗化为主要的软化机制；然而7050合金侧的维式硬度变化较复杂，原因归结为固溶强化、弥散强化和增强相的溶解的混合作用。%Homogenization annealing of the 7050/6009 bimetal slab prepared by direct-chill casting was investigated and its effects on microstructural evolution, composition distribution and mechanical properties in the interfacial region of the bimetal were studied. The results show that the optimized homogenization annealing process was 460°Cfor 24 h. After homogenization annealing, the Zn-rich phases and Al15(FeMn)3Si2phases were precipitated at the interface of the bimetal. The diffusion layer thickness of homogenized bimetal increased by 30 µm from 440 to480°Cfor 24 h, while it increased by 280 µm from 12 to 36 h at 460°C. The Vickers hardnessesat 6009 alloy side and interface of the bimetal decreased after homogenized annealing and grain coarsening was considered asthedominating softening mechanism.The hardness variation at 7050 alloy side was complicated due to the combined action of solution strengthening, dispersion strengthening and dissolution of reinforced phases.