Influence of grain size on the flow properties of an Al-Mg-Sc alloy over seven orders of magnitude of strain rate

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• 作者：Pedro Henrique R. Pereira^a ; ^b ; Ying Chun Wang^c ; Yi Huang^a ; ^{y.huang@soton.ac.uk} ; Terence G. Langdon^a
• 关键词：Aluminium alloys ; Dynamic testing ; Equal-channel angular pressing ; Hall-Petch relationship ; Superplasticity
• 刊名：Materials Science and Engineering: A
• 出版年：2017
• 出版时间：8 February 2017
• 年：2017
• 卷：685
• 期：Complete
• 页码：367-376
• 全文大小：2407 K
• 卷排序：685

文摘

Experiments were conducted to evaluate the flow properties of an Al-3Mg-0.2Sc alloy both without and with processing using equal-channel angular pressing (ECAP). The initial grain size was ~300 µm and this was reduced to ~250 nm by ECAP and then increased to ~600 nm by annealing at 673 K for 10 min. Tests were conducted to determine the mechanical properties over seven orders of magnitude of strain rate from ~10−4 to ~103 s−1. The results confirm the validity of the Hall-Petch relationship in the material processed by ECAP. Shear banding occurred in the coarse-grained material during dynamic testing but in the ECAP-processed alloy there was only minor grain coarsening. There was evidence for dynamic strain ageing in both the coarse and the ultrafine-grained (UFG) alloy with a transition in flow mechanism at high temperatures from dislocation climb in the coarse-grained material to superplasticity in the UFG alloy.