A comparative study of spark plasma sintering and hybrid spark plasma sintering of W-4.9ni-2.1Fe heavy alloy
- Authors: Shongwe, Mxolisi Brendon , Diouf, Saliou , Durowoju, Mondiu Olayinka , Olubambi, Peter Apata , Ramakokovhu, Munyadziwa Mercy , Obadele, Babatunde Abiodun
- Date: 2016
- Subjects: Tungsten heavy alloys , Spark plasma sintering , Microstructure
- Type: Article
- Identifier: http://hdl.handle.net/10210/123454 , uj:20793 , Citation: Shongwe, M.B. et al. 2016. A comparative study of spark plasma sintering and hybrid spark plasma sintering of W-4.9ni-2.1Fe heavy alloy.
- Description: Abstract: Mixed 93W-4.9Ni-2.1Fe powders were sintered via the spark plasma sintering (SPS) and hybrid spark plasma sintering (HSPS) techniques with 30 mm and 60 mm samples in both conditions. After SPS and HSPS, the 30 mm and 60 mm alloys (except 60mm-SPS) had a relative density (>99.2%) close to the theoretical density. Phase, microstructure and mechanical properties evolution of W-Ni-Fe alloy during SPS and HSPS were studied. The microstructural evolution of the 60 mm alloys varied from the edge of the sample to the core of the sample. Results show that the grain size and the hardness vary considerable from the edge to the core of sintered sample of 60 mm sintered using conventional SPS compared to hybrid SPS. Similarly, the hardness also increased from the edge to the core. The 60 mm-HSPS alloy exhibit improved bending strength than the 60 mm-SPS, 1115 MPa and 920 MPa respectively, former being similar to the 30 mm-SPS and HSPS alloys. The intergranular fracture along the W/W grain boundary is the main fracture modes of W-Ni-Fe, however in the 60 mm-SPS alloy peeling of the grains was also observed which diminished the properties. The mechanical properties of SPS and HSPS 93W-4.9Ni-2.1Fe heavy alloys are dependent on the microstructural parameters such as tungsten grain size and overall homogeneity.
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Fabrication and characterization of titanium-nickel-zirconia matrix composites prepared by spark plasma sintering
- Authors: Obadele, Babatunde Abiodun , Ige, Oladeji Oluremi , Olubambi, Peter Apata
- Date: 2017
- Subjects: Spark plasma sintering , Zirconia , Titanium
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/225471 , uj:22773 , Citation: Obadele, B.A., Ige, O.O. & Olubambi, P.A. 2017. Fabrication and characterization of titanium-nickel-zirconia matrix composites prepared by spark plasma sintering.
- Description: Abstract: Ti–Ni–ZrO2 composites were prepared by spark plasma sintering (SPS). The effect of ZrO2 content on the densification, microstructure and microhardness properties of the composites were investigated. Samples were characterized by SEM, EDS and XRD analyses. Noticeably, SPS process under the sintering conditions was achieved at a sintering temperature of 950 ºC, for 10 min holding time, at 100 °C/min of heating rate and at an applied pressure of 50 MPa. This resulted in maximum densification of the powder compact and the formation of a distinguishable spherical globules rich in Ni surrounding the retained Ti. Gradient composition distribution of ZrO2 at the grain boundaries resulted into pinning effect of the grain growth. As the ZrO2 content increased from 5 to 10 vol.%, it was accompanied by a significant increase in hardness values of the sintered composites from 480 to 713 HV.
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Influence of nanocrystalline nickel powder on oxidation resistance of spark plasma sintered Ni-17Cr6.5Co1.2Mo6Al4W7.6Ta alloy
- Authors: Babalola, Bukola Joseph , Maledi, Nthabiseng , Shongwe, Mxolisi Brendon , Bodunrin, Michael Oluwatosin , Obadele, Babatunde Abiodun , Olubambi, Peter Apata
- Date: 2020
- Subjects: Nickel based superalloy , Nanostructured , Spark plasma sintering
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/453453 , uj:40033 , Citation: Babalola, B.J. et al. 2020. Influence of nanocrystalline nickel powder on oxidation resistance of spark plasma sintered Ni-17Cr6.5Co1.2Mo6Al4W7.6Ta alloy. , DOI: https:// doi.org/10.1016/j.jksues.2019.01.002
- Description: Abstract: An investigation was carried out to evaluate the isothermal oxidation behavior of nickel based superal- loys at 1100 °C for 120 h. The alloys which were microstructured and nanostructured were developed by spark plasma sintering system. The oxidation test was carried out at a temperature of 1100 °C in air at different exposure time up to 120 h. The nanostructured nickel based alloy possessed better oxidation resistance with the formation of continuous adherent alumina, chromia scales, and spinel on the alloy surface and with no significant internal oxides. The oxidation rate of NiO was observed to be lower in the nanostructured nickel superalloy due to low diffusion rate of Nickel. The oxidation kinetics followed a parabolic oxidation law.
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