ECAP挤压L2纯铝的微观组织演化规律  

Microstructural Evolution Laws of Pure Al L2 During Equal Channel Angular Pressing

作　　者：张忠明[1] 徐春杰[1] 田景来[1] 王锦程[2] 郭学锋[1] 

机构地区：[1]西安理工大学材料科学与工程学院,陕西西安710048 [2]西北工业大学凝固技术国家重点实验室,陕西西安710072

出　　处：《西安理工大学学报》2005年第3期227-231,共5页Journal of Xi'an University of Technology

基　　金：航空科学基金(02G53052);陕西省自然科学研究计划项目(2003E1);陕西省教育厅专项科研计划项目(03JK132);凝固技术国家重点实验室开放课题资助项目(200401)

摘　　要：用等通道转角挤压对纯铝L2进行10道次挤压,结果表明:挤压1道次后,原来晶粒尺寸为1 mm的等轴晶沿剪切方向被拉长为条带状晶,在条带状晶粒之间出现被剪切破碎的细小亚晶粒。挤压2道次后,出现了少量等轴晶。挤压4道次后,晶粒取向性变得不太明显,小角度晶界的亚晶粒逐步向大角度晶界的等轴晶演化,晶粒细化到1μm。随挤压道次的继续增加,晶粒大小不再变化,而形状向等轴状演化。挤压10道次后,合金组织由晶粒大小为1μm的等轴晶组成。ECAP挤压中,纯剪切变形和应变量的双重作用导致晶粒细化。当晶粒尺寸小于临界尺寸时,剪切变形对晶粒的细化起主要作用;当达到临界尺寸后,应变量起主要作用,表现在使合金组织形貌向等轴晶转变。The billets of industrial pure aluminum L2 alloy were pressed by equal-channel angular pressing （ECAP） technique for 10 passes. The result shows that after 1 pressing, the original coarse equiaxed grains （grain size is 1 mm） turns to be band-like grain textures in the shearing direction;and that smaller sub-grains produced by severe shearing deformation distribute between band-like grains. After 2 pressings, small amount of fine equiaxed grains appear in the microstructure. After 4 pressings, orientation of the grains is not distinct, and sub grains with small angle grain boundary tend to have been transformd to equiaxed grains with high angle boundary, and the grain size is refined to 1 μm. As the pressing passes increase, the ratio of fine equiaxed grains in microstructure is increasing. After the alloy is pressed for 10 passes, the microstructures consist of all fine equiaxed grains and grain size is 1 μm. Grain refinement in ECAP can be attributed to pure shear deformation and strain amount, but the two factors play different role in different stages. When the grain size of the alloy is smaller than the critical grain size, pure shear deformation plays a main role in grain refinement; while the grain size of the alloy reaches the critical grain size, strain amount plays a main role,as shown in making the alloy structure appearance transform into all fine equiaxed grains.

关 键 词：等通道转角挤压(ECAP) 组织演化 细化机制 

分 类 号：TG111.7[金属学及工艺—物理冶金] TG113.12[金属学及工艺—金属学]