Giant hardening and formation of nanograined supersaturated solid solution in Al–Zn system

Abstract

Grain refinement via severe plastic deformation (SPD) can induce the decomposition of Al–Zn supersaturated solid solution, resulting in strain softening rather than hardening. So far, it is very challenging to improve the strength of binary Al–Zn alloy by refining grains through SPD. Herein, a single-phase supersaturated solid solution nanostructure with relaxed grain boundaries has been successfully generated in Al–21.7 at% Zn alloy by cryogenic high-pressure torsion. Instead of softening, giant hardening is achieved. The nanocrystalline Al–Zn alloy with grain size of 15 nm has an ultrahigh yield strength of about 642 MPa.

GRAPHICAL ABSTRACT

IMPACT STATEMENT

Giant hardening has been achieved in Al–Zn alloy with extremely fine nanograins and single-phased supersaturated solid solution under extremely high shear strain via cryogenic high-pressure torsion.

KEYWORDS:

• Al–Zn alloy
• high strength
• supersaturated solid solution
• grain boundary relaxation
• phase decomposition

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financially supported by the National Natural Science Foundation of China [grant numbers 52101161, 52171088 and 52225102] and the Ministry of Science and Technology of the People's Republic of China [grant number 2017YFA0700700] and the Young Elite Scientists Sponsorship Program by CAST [grant number 2022QNRC001].