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The dependence of mechanical properties of aluminium matrix composites on the size ratio of their constituent powders

Dunne, Adrian (2004) The dependence of mechanical properties of aluminium matrix composites on the size ratio of their constituent powders. Master of Engineering thesis, Dublin City University.

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Abstract

In the powder metallurgy method of composite material production it has been noted that the size ratio, between the constituent powders used in Aluminium-Silicon Carbide non-continuously reinforced metal matrix composites (MMCs), has a bearing on the final mechanical strength of the material. The exact mechanism is not understood. This work concentrates on how the difference in size ratios between the powders affects the packing fraction when the powders are poured into a die, before compaction, and how this is related to the final mechanical strength of the material. The packing of binary powders was firstly treated mathematically. An analytical model to predict the packing fraction of the powder was then tested to ensure its accuracy when used with metal powders of this type. The model was found to predict the packing fraction of the powders used to manufacture these materials within a range of 8%. Powder mixtures of various size ratios were then used to prepare material samples and the changes in packing fraction compared to the changes in the mechanical properties of the material. Comparison of the changes of mechanical properties of the materials as size ratio is changed, with the way that packing fraction changes with packing fractions shows that they alter in a similar manner. It is concluded that the change in powder size ratio leads to a change in the packing fraction of the powders before compaction, which leads to a change in the mechanical strength. However it is shown that other factors such as powder size and sintering times and temperatures also have an important part to play. It is also shown that the powders of differing sizes must be present in sufficient quantities to achieve high packing fractions. Therefore it may be easier, and cheaper, to successfully sinter material made from mixtures of powders where significant portions of powders of different sizes are used.

Item Type:Thesis (Master of Engineering)
Date of Award:2004
Refereed:No
Supervisor(s):Looney, Lisa and Murphy, Jerry
Uncontrolled Keywords:metallurgy; metal matrix composites; MMCs; Aluminium-Silicon Carbide
Subjects:Engineering > Materials
Engineering > Mechanical engineering
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Engineering and Computing > School of Mechanical and Manufacturing Engineering
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 License. View License
ID Code:17189
Deposited On:16 Aug 2012 14:46 by Fran Callaghan. Last Modified 16 Aug 2012 14:46

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