——顯微組織演化
(中南大學 粉末冶金國家重點實驗室，長沙 410083)
摘 要: 研究了純鋁在3種（A、 B和C）不同等徑角擠工藝中的顯微組織演化。 結(jié)果表明: 純鋁經(jīng)過等徑角擠壓變形后， 其顯微組織特征與加工路線有很大的關系。 提出了立方元素扭轉(zhuǎn)模型， 分析了3種不同加工路線的剪切面和剪切方向， 較好地解釋了采用3種不同路線擠壓后材料顯微組織的演化規(guī)律。在路線C（各道次擠壓間試樣旋轉(zhuǎn)180°)中， 每次擠壓樣品總是在相同的剪切面上發(fā)生剪切， 每相鄰道次之間的剪切方向相反， 前一次變形產(chǎn)生的剪切應變被隨后緊接著的下一次擠壓所抵消，這導致了多余的剪切應變；在路線A(各道次擠壓間試樣不旋轉(zhuǎn))中，有兩個相交成60°的剪切面， 剪切交替地在兩個剪切面上進行；在路線B（各道次擠壓間試樣旋轉(zhuǎn)90°）中， 存在4個不同的剪切面和剪切方向， 擠壓交替地在4個剪切面上進行， X， Y/和Z平面上的晶粒都發(fā)生了剪切， 這有利于等軸晶結(jié)構的形成。
關鍵字: 等徑角擠； 純鋁； 顯微組織
(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
