高纯铝等通道转角挤压引起的微观组织变化

高纯铝经等通道转角挤压 (EqualChannelAngularExtrusion/Pressing)后 ,其组织会发生显著变化。采用自制转角为 φ =10 0° ,ψ =16°的挤压模具 ,在液压试验机上对晶粒直径为 1.0mm的退火高纯铝实施挤压。挤压过程中的塑性剪切应变为 1.5 7,平均一次挤压 (N =1)的等效塑性应变为 0 .912。在扫描电镜上利用背散射电子衍射(EBSD)和ECC新分析技术研究了等通道转角挤压对微观组织的影响。实验结果表明 ,经过一次挤压 ,许多原始晶界沿剪切变形方向伸直 ,等轴晶粒变成沿剪切方向排列的片层结构 ,晶内出现直径约 1.0 μm的大量亚晶。经过多次挤压的高纯铝试样在室温便出现再结晶 ,EBSD分析确定再结晶组织中存在立方织构

Microstructural changes in high purity aluminium subjected to equal channel angular extrusion

The microstructural evolution has been investigated during shear deformation produced by the Equal Channel Angular Extrusion (ECAE) technique in a high purity Aluminium.A die with channel angle φ=100°,ψ=16° is made for the extrusion.The plastic shear deformation strain obtained by each passage through the die is 1.57,while the equivalent strain is 0.912.The change in grain size from initial 1.0mm to about 1.0μm occurs after N(=1 and 3)extrusion passages.Electron Back Scatter Diffraction (EBSD) and Electron Channel Contract (ECC) techniques are used for the structure observation.The experimental results show that ,after one passage through the die,the initial equiaxed grains become lath structure and a lot of initial grain-boundaries align along the shear deformation direction,substurctures and sub-grains appear within the grains;when the extruded samples are laid up at ambient temperature for about one month,the recrystallization occurs,and the typical cubic texture is firstly found in these recrystallized grains.