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Project C2: Micro- and nano-scale composites | |||
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| Project Leader: Associate Professor Carlos Cáceres - University of Queensland | Staff/students |
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| C2.1 | Cáceres, Carlos Dahle, Arne Nagasekhar, Anumalasetty Xu, Wei Lui, Ed Bian, Singhai Xia, Kenong Wu, Xiaolin Al-Goussous, Shouqie Ng, HP Muddle, Barry |
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| Micro-truss structures are characterised by extreme stiffness and high mechanical efficiency (i.e., high stiffness/mass ratio) as well as by an increasing strength as the cell size of the structure is reduced. The latter effect opens the possibility of using the scale of the micro-truss structure as a design parameter. | ||||
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| The yield strength of hpdc Mg-Al alloys seems to be determined by the percolating β-phase intermetallic structure which is thought to behave like a pseudo micro-truss structure). (The link across the cells body converting the compliant foam into a stiff micro-truss structure is provided by the matrix alloy, hence the “pseudo” prefix). Experiments show that as the intermetallic structure becomes finer, e.g, for thinner castings, the yield strength of the casting increases, as expected for a micro-truss structure. This study will use high resolution x-ray tomography to characterise the 3-D morphology of the intermetallic structure in alloys with predetermined contents of Al in order to characterise the micro-truss structure, and in situ tensile testing to correlate the plastic behaviour of the alloys with the cracking of the intermetallic structure. This information should enable understanding the origin of the yield strength, the skin effect, the yielding behaviour, the strain hardening behaviour at low strains, the development of damage and the bound imposed by the cracking of the intermetallic structure to the alloy’s ductility. | ||||
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| C2.2 | ||||
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| Research involves improved fundamental understanding of the role of pre-existing static defects and dynamic processes such as solute clustering in the heterogeneous nucleation of strengthening precipitate phases. Key elements of the project will include: | ||||
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| • | High resolution imaging (TEM) and analysis (APFIM, FEG-TEM) of nanoscale aggregates. | |||
| • | Thermo-chemical modelling of solute interactions. | |||
| • | Modelling and simulation of aggregation and segregation phenomena. | |||
| • | Modelling of heterogeneous nucleation. | |||
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| C2.3 | ||||
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| The objective of the project is to significantly enhance mechanical properties of existing light alloys including room temperature strength and ductility and high temperature creep resistance and to achieve a good combination of these properties. The project will integrate design of microstructure, realisation of the designed microstructure through novel processing, characterisation of microstructure and mechanical behaviour, and modelling of the correlation between microstructure and mechanical behaviour. | ||||
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