Effect of pressing temperature on fine-grained structure formation in 7475 aluminum alloy during ECAP
Effect of pressing temperature on fine-grained structure formation in 7475 aluminum alloy during ECAP
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DOI：
10.1016/j.msea.2004.04.049
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发表时间：
2004-09-15
期刊：
影响因子：
6.4
通讯作者：
Sakai, T
中科院分区：
文献类型：
--
作者：
Goloborodko, A;Sitdikov, O;Sakai, T
在523 ~ 673 K温度范围内，研究了挤压温度对7475铝合金ECAP变形组织的影响。通过使用途径A将样品压制至多达12个菌株。经过3道次ECAP变形后，新的具有大角度晶界的等轴晶（HABS）开始形成，并随着反复ECAP变形而逐渐发展，最后完全发展成新的细晶组织。随着压制温度的升高，平均（亚）晶粒尺寸趋于增大，纵横比减小。应变诱导位错晶界的取向差分布在第二道次前呈单峰型，随着应变的增加逐渐向大角度方向移动。压制温度的升高延缓了从低角度晶界到高角度晶界的转变动力学，而后者的分数以及平均取向差在高应变下接近相同的饱和值，而与温度无关。探讨了ECAP过程中超细晶的形成机理。(C)2004 Elsevier B. V.保留所有权利。
The effect of pressing temperature on microstructural development under ECAP conditions was studied in an as-cast 7475 aluminum alloy at temperatures from 523 to 673 K. The samples were pressed by using route A up to strains of 12. New equiaxial grains with high angle boundaries (HABS) start to be formed after three passes and then gradually developed with repeated ECAP, finally, followed by fully development of a new fine-grained structure. The average (sub)grain size tends to increase and the aspect ratio decreases with increasing pressing temperature. The misorientation distribution of strain-induced dislocation boundaries shows a single peak type at low angle misorientations until second pass and then gradually shifts to higher angles with increasing of strain. Increase in pressing temperature retards the transformation kinetics from low angle boundaries to high angle ones, while the fraction of the latter as well as the average misorientation approach a same saturation value irrespective temperature in high strain. The mechanism of ultra-fine grain formation during ECAP is discussed. (C) 2004 Elsevier B.V. All rights reserved.