Investigation of the C-Ni-V ternary phase diagram and development of an optimum wear resistant alloy
Date
2018
Authors
Fabuyide, Abosede Adefunke
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Abstract
The C-Ni-V ternary phase diagram was investigated. The eutectics of ten as-cast samples
produced by Apata [2014Apa1] were re-analysed. The results obtained were compared with
previous analyses by Apata [2014Apa1] and Muobeleni [2013Muo]. The differences in
eutectic analyses were identified. Six new samples were produced and analysed in the as-cast
condition, as well as after annealing at 1000°C for 1000hours and water quenched. The
phases in the alloys were identified using SEM-EDX, EPMA and XRD. The solidification
projection of the new samples was constructed and the extensions of the binary phases were
determined. A new liquidus projection was derived using results of the new samples and
Apata’s [2014Apa1] samples and four ternary invariant reactions were identified, L + ~VC +
βV2C → σ′, L + βV2C → σ′ + (V), L + ~VC + σ′ → (Ni) and L + ~VC → (Ni) + C, of which
were slightly different from Apata [2014Apa1] and Muobeleni [2013Muo]. The isothermal
section of the new sample at 1000°C was plotted
Six VC-Ni alloys (from VC and Ni powders) and seven V-C-Ni alloys (from VC, V and Ni
powders) were produced by spark plasma sintering. The sintered density, hardness, fracture
toughness, wear performance and corrosion performance in 1M H2SO4 and 3.5wt% NaCl
environments of the alloys were evaluated. Alloys with 10 at.% Ni had the preferred
combination of properties, and Alloy V48:C42:Ni10 (at.%) was the optimum alloy with the
following properties: 97.6% sintered density, wear rate of 3.03 ± 0.00(1) 10-6 mm3/Nm
against a Si3N4 ball, corrosion rates of 0.0176mm/y in 1M H2SO4 environment, and
0.00295mm/y in 3.5wt% NaCl environment.
Description
A thesis submitted n fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering (Metallurgy and Materials), to the Faculty of Engineering and the Built Environment, University of the
Witwatersrand, Johannesburg, i Johannesburg, July 2018
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Citation
Fabuyide, Abosede Adefunke (2018) Investigation of the C-Ni-V ternary phase diagram and development of an optimum wear resistant alloy, University of the Witwatersrand, Johannesburg, https://hdl.handle.net/10539/26967