Abstract

Body-centred cubic magnesium-lithium-aluminium-base alloys are the lightest of all the structural alloys, with recently developed alloy compositions showing a unique multi-dimensional property profile. By hitherto unrecognised mechanisms, such alloys also exhibit exceptional immediate strengthening after solution treatment and water quenching, but strength eventually decreases during prolonged low temperature ageing. We show that such phenomena are due to the precipitation of semi-coherent D03-Mg3Al nanoparticles during rapid cooling followed by gradual coarsening and subsequent loss of coherency. Physical explanation of these phenomena allowed the creation of an exceptionally low-density alloy that is also structurally stable by controlling the lattice mismatch and volume fraction of the Mg3Al nanoparticles. The outcome is one of highest specific-strength engineering alloys ever developed.

Solution treatment and quenching can strengthen magnesium-lithium-aluminium alloys, but this strength decreases with ageing. Here, the authors show this is due to semi-coherent nanoparticle precipitation followed by coarsening, and control the lattice mismatch to stabilise the microstructure.

Details

Title
Precipitation strengthening in an ultralight magnesium alloy
Author
Tang, Song 1 ; Tongzheng, Xin 1 ; Xu Wanqiang 1   VIAFID ORCID Logo  ; Miskovic, David 1 ; Sha Gang 2 ; Quadir Zakaria 3 ; Ringer, Simon 4   VIAFID ORCID Logo  ; Nomoto Keita 4 ; Birbilis Nick 5   VIAFID ORCID Logo  ; Ferry, Michael 1 

1  The University of New South Wales, School of Materials Science and Engineering, Sydney, Australia (GRID:grid.1005.4) (ISNI:0000 0004 4902 0432) 
2  Nanjing University of Science and Technology, Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing, China (GRID:grid.410579.e) (ISNI:0000 0000 9116 9901) 
3  Curtin University, Microscopy and Microanalysis Facility, John de Laeter Centre, Bentley, Australia (GRID:grid.1032.0) (ISNI:0000 0004 0375 4078) 
4  The University of Sydney, School of Aerospace, Mechanical and Mechatronic Engineering and Australian Centre for Microscopy and Microanalysis, Sydney, Australia (GRID:grid.1013.3) (ISNI:0000 0004 1936 834X) 
5  Monash University, Department of Materials Science and Engineering, Melbourne, Australia (GRID:grid.1002.3) (ISNI:0000 0004 1936 7857) 
Publication year
2019
Publication date
Dec 2019
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
DOI
https://doi.org/10.1038/s41467-019-08954-z
ProQuest document ID
2187154764
Copyright
This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.