中文摘要：

对纯铝粉末材料进行200℃单道次等径角挤扭（ECAPT）变形实验研究。采用光学显微镜（OM）、电子背散射技术（EBSD）和透射电子显微镜（TEM）观察和分析变形组织微观结构的变化规律，获得有关晶粒形貌、晶粒尺寸以及晶粒取向分布的信息。结果表明：ECAPT工艺对粉末材料具有强烈的致密和细化效果，1道次ECAPT变形后组织接近完全致密，晶粒细化效果明显，平均晶粒尺寸约为5．2μm；晶粒尺寸分布不均匀，亚晶界和小角度晶界所占比例较高；变形组织内部形成了明显的择优取向，沿剪切方向均匀对称分布，以剪切织构类型为主；200℃条件下，纯铝粉末材料单道次ECAPT变形过程中，晶粒的显著细化主要得益于材料组织所承受的剧烈剪切变形和内部所累积的大量有效应变。

英文摘要：

Pure A1 particles were successfully consolidated into nearly dense bulk materials by equal channel angular pressing and torsion （ECAPT） at 200 ℃. The microstructures were characterized using OM, EBSD and TEM for grain shape and size as well as misorientations. The results show that ECAPT is an effective technique and has potential in consolidating and refining the microstructures of powder materials. The consolidated material shows a fine structure with the grain size of around 5.2 ~tm, while the distribution of the grain size is not uniform. The microstructure mainly consists of elongated subgrains of low angle boundaries and fine equiaxed grains of high angle boundaries. In addition, there is a strong shear texture after 1 pass ECAPT. The grain refinement mechanism during a single pass of ECAPT is attributed to intensive shearing and large accμmulated strain