Superior strength–ductility combination in Al alloys via dislocation gradient structure

ABSTRACT

The precipitation hardening is widely applied to strengthen Al alloys. Here, we report an alternative way to achieve high-strength Al alloys via forming the dislocation gradient through pre-torsion. Remarkably, the gradient Al alloys exhibit a sharp increase in ultimate tensile strength up to 605 MPa yet nearly without reducing the uniform elongation, thereby outperforming their counterparts. The superior strength–ductility combination is ascribed to the excellent strengthening and strain hardening effects stemming from the substantial hetero-deformation-induced hardening in the coarse-grained gradient Al alloys. Our study thus paves a new way to improve the mechanical properties of Al alloys.

GRAPHICAL ABSTRACT

IMPACT STATEMENT

The gradient distribution of dislocations significantly increases the strength of the Al alloy with the neglectable reduction in uniform elongation, which enables exceptional mechanical properties that outperform the peak-aged counterpart.

KEYWORDS:

• Al alloys
• dislocation gradient
• HDI hardening
• mechanical properties

Acknowledgements

We would like to thank Prof. Xiaogang Wang at Hunan University for his help with LUR tests.

Disclosure statement

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

Additional information

Funding

This work was supported by National Natural Science Foundation of China [grant number 51820105001], Changsha Municipal Natural Science Foundation [grant number kq2202091], Natural Science Foundation of Hunan Province [grant number 2022JJ30712], and State Key Laboratory of Powder Metallurgy, Central South University, Changsha, China and The Science and Technology Innovation Program of Hunan Province [grant number 2022RC3035].