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Posted: September 8, 2010
New super strong nanostructured alloy discovered
(Nanowerk News) University of Sydney researchers have discovered a new super-strength light alloy and had their key findings published in the prestigious journal, Nature Communications.
The alloy is much stronger than expected and the reasons are being revealed by top-end microscopy and microanalysis at the University's node of the Australian Microscopy and Microanalysis Research Facility (AMMRF).
Dr Peter Liddicoat next to the atom probe.
Dr Peter Liddicoat and Professor Simon Ringer from the Australian Centre for Microscopy and Microanalysis (ACMM) and Dr Xiaozhou Liao from the University of Sydney's School of Aerospace, Mechanical and Mechatronic Engineering, have headed up this international collaborative project.
The purpose of their research has been to understand the relationship between the alloy's properties and its structure at the atomic level.
The importance of developing new lightweight alloys cannot be overestimated and will enable improved technologies, particularly in aerospace and automotive applications and in construction.
The alloy produced by Dr Liddicoat and the rest of the team is much stronger than previous crystalline metals.
It has high strength and good ductility, a highly sought-after combination, and the physical improvements observed were significantly beyond what was predicted by standard rules.
To understand this improvement, Dr Liddicoat characterised the nanostructure of the alloy by using atom probe tomography at the ACMM, allowing the structure of the grains and tiny clusters of solute atoms to be visualised. The grains were just tens of nanometres in diameter with accumulations of solute atoms apparent along the boundaries between the grains.
The unexpectedly high level of strengthening appears to be due to two factors. Firstly, the way that the alloying elements are arranged within the grains is thought to increase the dislocation-storage capacity of the alloy. Secondly, the clustering of elements between the grains could limit nanocrystal growth, increase the cohesion of the grains, and resist embrittlement and defect generation.
Dr Liddicoat is very enthusiastic about understanding alloys in this way.
"Being able to really see what is happening inside our alloys at the atomic level has been a huge help in investigating their amazing properties," he said.
"An exciting aspect of the study was our development of breakthrough new atom probe methods to measure the orientation of nanometre-sized crystals to assess 'nanotexture'."