对不同路径和不同道次下铝粉烧结材料的等通道转角挤压工艺进行了试验研究, 用光学显微镜、扫描电子显微镜和透射电镜分析了粉末烧结材料在不同工艺条件下的晶粒细化规律和致密行为, 并测量了挤压后试样的密度和硬度等性能. 结果表明, 等通道转角挤压工艺对粉末烧结材料具有很强的致密效果和细化效果, 可显著提高其力学性能. 在单道次变形中, 大剪切塑性变形和高静水压力状态是粉末烧结材料获得良好的致密效果的关键; 在多道次变形中, 变形量的累积和不同的剪切特征不断地改变内部的孔隙形状, 使内部基体材料进一步致密. 而晶粒的细化效果则取决于变形中的静水压力、变形量和剪切特征等关键因素.
Experiments of ECAE were conducted for pure aluminum powder sintered material under different routes and passes. The grain refinement regulation and densification behavior of powder material during ECAE were deeply investigated under different conditions with optical telescope, scan electronic telescope and transmission electronic telescope. The density and hardness of the extruded samples were measured. The experiment results show that ECAE has powerful densification and refinement effects and the mechanical properties of powder materials are improved In single ECAE, large shear plastic deformation and high hydrostatic stress state are the key factors to obtain high density material In multiple passes ECAE, the inner pore shape is changed and the powder material is compacted further by the accumulated deformation and different shear deformation characters. The grain refinement effect depends on some key factors such as hydrostatic stress, strain and shear deformation character etc.
参考文献
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