High-Strength Nanotwinned Al Alloys with 9R Phase

Qiang Li; Sichuang Xue; Jian Wang; Shuai Shao; Anthony H Kwong; Adenike Giwa; Zhe Fan; Yue Liu; Zhimin Qi; Jie Ding; Han Wang; Julia R Greer; Haiyan Wang; Xinghang Zhang

doi:10.1002/adma.201704629

High-Strength Nanotwinned Al Alloys with 9R Phase

Adv Mater. 2018 Mar;30(11). doi: 10.1002/adma.201704629. Epub 2018 Jan 22.

Authors

Qiang Li¹, Sichuang Xue¹, Jian Wang², Shuai Shao³, Anthony H Kwong⁴, Adenike Giwa⁴, Zhe Fan⁵, Yue Liu⁶, Zhimin Qi¹, Jie Ding¹, Han Wang¹, Julia R Greer⁴, Haiyan Wang¹, Xinghang Zhang¹

Affiliations

¹ School of Materials Engineering, Purdue University, West Lafayette, IN, 47907, USA.
² Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
³ Mechanical and Industrial Engineering, Louisiana State University, Baton Rouge, LA, 70803, USA.
⁴ Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA, 91125, USA.
⁵ Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA.
⁶ State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China.

PMID: 29356130
DOI: 10.1002/adma.201704629

Abstract

Light-weight aluminum (Al) alloys have widespread applications. However, most Al alloys have inherently low mechanical strength. Nanotwins can induce high strength and ductility in metallic materials. Yet, introducing high-density growth twins into Al remains difficult due to its ultrahigh stacking-fault energy. In this study, it is shown that incorporating merely several atomic percent of Fe solutes into Al enables the formation of nanotwinned (nt) columnar grains with high-density 9R phase in Al(Fe) solid solutions. The nt Al-Fe alloy coatings reach a maximum hardness of ≈5.5 GPa, one of the strongest binary Al alloys ever created. In situ uniaxial compressions show that the nt Al-Fe alloys populated with 9R phase have flow stress exceeding 1.5 GPa, comparable to high-strength steels. Molecular dynamics simulations reveal that high strength and hardening ability of Al-Fe alloys arise mainly from the high-density 9R phase and nanoscale grain sizes.

Keywords: 9R; Al alloys; high strength; in situ; molecular simulation.