Investigation of a computationally predicted structure in the Ag-Pt system
Master Thesis
2013
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University of Cape Town
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Computational modelling is fast becoming the chosen way to predict novel structures. These structures need to be validated in order to gain credibility and generate more confidence in computational predictions. This investigation of the equiatomic region of the Ag-Pt system shows that computational modelling can be used successfully as a precursor to experimental investigations. Various techniques including electron microscopy, hardness and Differential Scanning Calorimetry were used to investigate different properties of the alloy. These techniques have shown that an ordered phase may exist in the Ag-Pt system. This ordered phase has been shown to have an increased hardness and has produced extra reflections in electron diffraction patterns. Scanning Electron Microscope equipped with a Backscattered Electron detector has shown that a third phase is present in the alloy and the composition is close to 50:50; within experimental error. The alloys showed considerable inhomogeneity and it was not homogenised prior to or post cold rolling. This could be a reason for the third phase not reaching an equilibrium state after prolonged heat treatments. The final structure might be the L11 structure but the full transformation is slow and further investigation is required. It is recommended that future research be carried out taking into account the recommendations provided in Chapter 7.
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Allies, S. 2013. Investigation of a computationally predicted structure in the Ag-Pt system. University of Cape Town.