Influence of Mg on tensile deformation behavior of high Mg-content Al-Mg alloys. (October 2022)

• Record Type: Journal Article
• Authors: Zhou, Dengshan; Zhang, Xiuzhen; Wang, Hao; Li, Yue; Sun, Binhan; Zhang, Deliang
• Is Part Of: International journal of plasticity. Volume 157(2022)
• Publication Date: 2022-10
• Subjects: High Mg-content Al-Mg alloys -- Dynamic strain aging -- Strain hardening -- Dynamic recovery -- Apparent activation volume; Plasticity -- Periodicals; Plasticité -- Périodiques; Plasticity; Periodicals; 620.11233
• DOI: 10.1016/j.ijplas.2022.103405
• Languages: English
• ISSNs: 0749-6419

Abstract

Highlights: Dynamic strain aging (DSA) occurred immediately after macroscopic yielding in high Mg-containing Al-Mg alloys. The occurrence of DSA at large strains affected the linear addition law of the flow stress of Al-Mg alloys. The dislocation accumulation rate and dynamic recovery rate in Al-Mg alloys upon room-temperature tensile deformation changed differently with the strain rate and Mg content. The occurrence of DSA markedly affected the thermally-activated deformation of Al-Mg alloys. Abstract: Al-Mg based alloys are known to experience dynamic strain aging (DSA) at room temperature, which is often associated with the diffusion of mobile Mg atoms to dislocation segments temporarily arrested at obstacles (e.g., forest dislocations) upon deformation in the DSA regime. With the emergence of new promising high Mg-content (> 6 wt.%) Al-Mg alloys, the combined effects of Mg content and DSA on their tensile flow behavior need to be better understood. In the present work, the tensile deformation behavior of Al and Al-(5.3, 6.4, 7.6 and 8.7) wt.% Mg samples tested at room temperature and at strain rates ranging from 0.0001 to 0.1 s −1 was investigated, based on the Kocks-Mecking-Estrin model combined with a DSA model, the Haasen plot as well as transmission electron microscopy. Particular focuses are placed on the influence of Mg solutes on DSA and associated strain hardening effects, on dislocation accumulation and annihilation as well as on apparent activation volume. We show that the synergistic effect of the Mg-dislocation interactions and DSA effectively reduces the rate of dynamic recovery via suppressing dislocation cross-slip, leading to an enhanced strain hardening capacity for the Al-Mg alloys with a higher Mg content. The influences of DSA on the yield strength, flow stress and apparent activation volume of thermally-assisted deformation of the Al-Mg alloys are also discussed to elucidate fundamental insights into the development of new high Mg-content Al-Mg alloys with superior mechanical performance.