——显微组织演化
(中南大学 粉末冶金国家重点实验室，长沙 410083)
摘 要: 研究了纯铝在3种（A、 B和C）不同等径角挤工艺中的显微组织演化。 结果表明: 纯铝经过等径角挤压变形后， 其显微组织特征与加工路线有很大的关系。 提出了立方元素扭转模型， 分析了3种不同加工路线的剪切面和剪切方向， 较好地解释了采用3种不同路线挤压后材料显微组织的演化规律。在路线C（各道次挤压间试样旋转180°)中， 每次挤压样品总是在相同的剪切面上发生剪切， 每相邻道次之间的剪切方向相反， 前一次变形产生的剪切应变被随后紧接着的下一次挤压所抵消，这导致了多余的剪切应变；在路线A(各道次挤压间试样不旋转)中，有两个相交成60°的剪切面， 剪切交替地在两个剪切面上进行；在路线B（各道次挤压间试样旋转90°）中， 存在4个不同的剪切面和剪切方向， 挤压交替地在4个剪切面上进行， X， Y/和Z平面上的晶粒都发生了剪切， 这有利于等轴晶结构的形成。
关键字: 等径角挤； 纯铝； 显微组织
(ECAP) of pure Al(I)
——microstructure evolution
（State Key Laboratory for Powder Metallurgy, Central South University,
Changsha 410083, China）
Abstract:The microstructure evolution of pure aluminum in different equal channel angular pressing (ECAP) routes was investigated. The results show that the microstructure of pure Al highly depends on the routes of ECAP. In order to analyze the shearing plane and shearing direction of the three routes, and to extrapolate the microstructure evolution during these routes, a cubic-unit-based torsion model was suggested. In route C, every shear deformation happens on the same shearing plane, but the shearing direction reverses in two preceded steps, and excessive deformation remains after one shear deformation is counteracted by the subsequent shear deformation. In route A, there are two shearing planes intersecting by 60°. In route B, there are four different shearing directions, alternating on four different shearing planes, so all of the crystals on X, Y and Z planes are deformed, leading to the formation of equiaxed structure.
Key words: equal channel angular pressing; pure aluminum; microstructure
