Superplasticity and High Strength in Al–Zn–Mg–Zr Alloy with Ultrafine Grains. Issue 1 (21st August 2019)

• Record Type: Journal Article
• Authors: Valiev, Ruslan Z.; Kazykhanov, Vil U.; Mavlyutov, Aydar M.; Yudakhina, Anna A.; Chinh, Nguyen Q.; Murashkin, Maxim Yu
• Other Names: Kawasaki Megumi guestEditor.; Figueiredo Roberto B. guestEditor.; Zhilyaev Alexander P. guestEditor.
• Is Part Of: Advanced engineering materials. Volume 22:Issue 1(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-08-21
• Subjects: Al alloys -- high strength -- severe plastic deformation -- superplasticity -- ultrafine structures; Materials -- Periodicals; 620.11
• DOI: 10.1002/adem.201900555
• Languages: English
• ISSNs: 1438-1656

Abstract

Abstract : 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. Abstract : 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.