铝粉烧结材料等通道转角挤压组织性能演变及机理分析
首发时间:2009-01-15
摘要:等通道转角挤压工艺是制备块体超细晶材料的有效方法。本文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,采用光学显微镜、扫描电子显微镜和透射电镜深入分析了粉末烧结材料在不同工艺条件下晶粒细化规律和致密行为,并对挤压后试样的密度和硬度等性能进行测试。研究结果表明,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,可显著提高粉末材料的力学性能。其中,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能够获得良好的致密效果的关键所在;同时,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,使得内部基体材料进一步致密。而晶粒的细化效果取决于变形中的静水压力、变形量和剪切特征等关键因素。这些研究为大塑性变形方法在粉末材料领域的应用提供必要的理论基础和依据。
关键词: 粉末烧结材料 等通道转角挤压 组织性能 致密和细化晶粒
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Microstructure and properties evolution and mechanism analysis of stined Aluminum powder during equal channel angular expression
Abstract:Equal channel angular extrusion (ECAE) is a new method to obtain ultra-fine grain materials.Experiments of ECAE are conducted for pure aluminum powder sintered material under different routes and passes.The grain refinement regulation and densification behavior of powder material during ECAE are deeply investigated under different conditions with optical telescope,scan electronic telescope and transmission electronic telescope.The density and hardness of the extruded samples are measured.The experiment results show,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.At the same time,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..These studies provide essential theoretical foundation for manufacturing the same material with SPD.
Keywords: sintered powder material equal channel angular extrusion microstructure and properties densification and grain refinement
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No.2790227089123200****
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