Strain rate sensitivity and deformation kinetics of ECAPed aluminium over a wide range of strain rates
Strain rate sensitivity and deformation kinetics of ECAPed aluminium over a wide range of strain rates
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DOI：
10.1016/j.msea.2012.09.100
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发表时间：
2013-01
期刊：
影响因子：
6.4
通讯作者：
T. Suo;Yuzeng Chen;Yulong Li;Cunxian Wang;Xueling Fan
中科院分区：
文献类型：
--
作者：
T. Suo;Yuzeng Chen;Yulong Li;Cunxian Wang;Xueling Fan
在应变速率为 10−3 至 103/s 的情况下，研究了经过 1-8 次等通道角冲压加工的铝的应变速率敏感性和表观活化体积。在准静态和动态载荷条件下进行的恒定应变率测试表明，经过最多 8 次压制的材料的应变率敏感性不断增加。然而，对于经过相同次数 ECAP 的样品，动态应变率灵敏度因子与准静态值相比增加了 3 至 6 倍。这一结果表明高应变率下的速率控制机制与低应变率下的速率控制机制不同。尽管准静态和动态加载条件下的表观活化体积随着道次次数的增加而减小，但Al ECAPed最多8道次的准静态活化体积大于100b3（其中b是铝的Burgers矢量），而动态值为~30b3。我们的实验结果和分析表明，变形动力学是由位错激活控制的。主要的速率控制机制被认为是准静态应变下的森林位错切割机制，而粘性阻力在动态变形的情况下也起着重要作用。
The strain rate sensitivity and apparent activation volume of aluminium processed by equal channel angular pressing for 1–8 passes are investigated at strain rates from 10−3to 103/s. Constant strain rate tests performed in compression under both quasi-static and dynamic loading conditions show a continuously increasing strain rate sensitivity for the material subjected up to 8 passes of pressing. However, for the specimens subjected to the same number of ECAP passes, the dynamic strain rate sensitivity factor exhibits a 3- to 6-fold increase compared to the quasi-static value. This result suggests that the rate-controlling mechanism at high strain rates is different from that at low strain rates. Although the apparent activation volume under both quasi-static and dynamic loading conditions decreases with increasing pass number, the quasi-static activation volume for the Al ECAPed up to 8 passes is greater than 100b3(where b is the Burgers vector of aluminium) while the dynamic value is ∼30b3. Our experimental findings and analysis suggest that the deformation kinetics are controlled by the dislocation activations. The dominant rate-controlling mechanisms are suggested to be the forest dislocation cutting mechanism at quasi-static strain while viscous drag also plays an important role in the case of dynamic deformation.