Effect of dynamic plastic deformation on the microstructure and mechanical properties of an Al-Zn-Mg alloy

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:784

Article

Afifi, Mohamed A.^1,2  Wang, Ying Chun^1,3  Langdon, Terence G.⁴ 

[1] Beijing Inst Technol, Sch Mat Sci & Engn, Beijing 100081, Peoples R China

[2] Brunel Univ London, Brunel Ctr Adv Solidificat Technol BCAST, Uxbridge UB8 3PH, Middx, England

[3] Natl Key Lab Sci & Technol Mat Shock & Impact, Beijing 100081, Peoples R China

[4] Univ Southampton, Dept Mech Engn, Mat Res Grp, Southampton SO17 1BJ, Hants, England

关键词: Al-Zn-Mg alloy;    Dynamic plastic deformation;    Precipitates;    Split-Hopkinson pressure bar;    Strain rate sensitivity;   

DOI  :  10.1016/j.msea.2020.139287

来源: Elsevier

【 摘 要 】

A supersaturated Al-Zn-Mg alloy was processed by dynamic plastic deformation (DPD) using a Split-Hopkinson pressure bar (SHPB) facility with strain range from 0.5 to 1.5 and then subjected to compressive testing at strain rates of 1 x 10(-3) -4 x 10(3) s(-1). The results show that there is concurrent occurrence of grain refinement, increase in dislocation density and precipitation of fine precipitates in different morphologies during DPD at strain over 1. This enhances the yield strength of the Al alloy after DPD over the as-received material in peak-aging state (T6). Grains are refined through the formation of low angle grain boundaries (LAGBs) by rearrangement of dislocations which leads to the subdivision of original grains. Heterogeneous coarse precipitates mainly of T (Al20Cu2Mn3) and E (Al18Mg3Cr2) phases distribute along dislocations and grain boundaries after DPD. Dynamic precipitation of very fine eta' and eta during DPD occurs where the volume fraction of precipitates increases with increasing the number of presses. The influence of precipitates on the strain rate sensitivity is also discussed.

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