分级均匀化对7055铝合金组织和力学性能的影响

采用差热分析、X射线衍射分析、光学显微镜、扫描电镜、透射电镜和常温拉伸等方法研究分级均匀化工艺对7055铝合金显微组织、枝晶偏析、Al3Zr粒子析出行为和力学性能的影响。结果表明:合金经(468℃、24h)+(473℃、4 h)的分级均匀化处理后,消除了铸锭晶界上的非平衡凝固共晶组织;铸锭先于264℃保温最有利于获得尺寸细小、均匀弥散分布的Al3Zr粒子;在单级均匀化基础上增加473℃的短时高温均匀化,能够提高合金基体中溶质原子的固溶度,增强时效强化效果,提高综合性能。

Effect of step-homogenization on microstructures and mechanical properties of 7055 aluminum alloy

The effects of step-homogenization on the microstructures,dendritic segregation,precipitation of Al3Zr particles and ultimate mechanical properties of aluminum alloy 7055 were studied by differential scanning calorimetry,X-ray diffractometry,optical microscopy,scanning electron microscopy,transmission electron microscopy and tensile test.The result show that the step-homogenization treatment,which comprises of the isothermal heating of the ingots at 468 ℃ for 24 h,then heating to 473 ℃ for 4 h,greatly eliminates the nonequilibrium solidified eutectic which exists on the grain boundaries.The previous heating at 264 ℃ is most favorable for the precipitation of fine and uniformly distributed Al3Zr particles.The additional short-term and high temperature heating at 473 ℃ on the basis of single-stage homogenization maximizes the solution ability of solid solute in the matrix,enhances the ageing strengthening effect and improves the comprehensive properties of the alloy.