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Superplasticity and High Strength in Al–Zn–Mg–Zr Alloy with Ultrafine Grains
Author(s) -
Valiev Ruslan Z.,
Kazykhanov Vil U.,
Mavlyutov Aydar M.,
Yudakhina Anna A.,
Chinh Nguyen Q.,
Murashkin Maxim Yu
Publication year - 2020
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201900555
Subject(s) - superplasticity , materials science , alloy , metallurgy , elongation , annealing (glass) , ultimate tensile strength , strain rate , severe plastic deformation , tensile testing , composite material
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.