Superplasticity and High Strength in Al–Zn–Mg–Zr Alloy with Ultrafine Grains

Herein, the ultrafine‐grained (UFG) 7xxx series alloy Al–4.8Zn–1.2Mg–0.14Zr demonstrates superplasticity at unusually low temperatures of 120–170 °C while maintaining its high‐strength state. The UFG structure is formed by high pressure torsion (HPT) at room temperature (RT), which leads to a consid...

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Bibliographic Details
Published in:Advanced engineering materials 2020-01, Vol.22 (1), p.n/a
Main Authors: Valiev, Ruslan Z., Kazykhanov, Vil U., Mavlyutov, Aydar M., Yudakhina, Anna A., Chinh, Nguyen Q., Murashkin, Maxim Yu
Format: Article
Language:English
Subjects:
Al alloys
high strength
severe plastic deformation
superplasticity
ultrafine structures
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Summary:Herein, the ultrafine‐grained (UFG) 7xxx series alloy Al–4.8Zn–1.2Mg–0.14Zr demonstrates superplasticity at unusually low temperatures of 120–170 °C while maintaining its high‐strength state. The UFG structure is formed by high pressure torsion (HPT) at room temperature (RT), which leads to a considerable increase in the strength characteristics by ≈60% compared with the material after conventional heat treatment T6. It is found that the UFG alloy exhibits thermostability when testing or annealing up to 170 °C. Deforming by tensile test at a strain rate of 10−4 s−1 and 10−3 s−1, the elongation to failure at 120 and 170 °C exceeds 250% and 500%, respectively, whereas the strain rate sensitivity reaches 0.45, which is a typical value characterizing superplastic deformation. After superplastic deformation, the UFG alloy maintains 25–50% higher strength characteristics at RT than that after conventional heat treatment T6. The origin of such superior behavior of the UFG alloy is discussed. Herein, the ultrafine‐grained (UFG) 7xxx series Al alloy processed by severe plastic deformation demonstrates superplasticity (SP) at unusually low temperatures of 120–170 °C while maintaining its high‐strength state. After SP deformation, the UFG alloy maintains 25–50% higher strength characteristics at room temperature than that after standard treatment T6. The origin of such superior behavior of the UFG alloy is discussed.
ISSN:1438-1656
1527-2648
DOI:10.1002/adem.201900555