Publications by authors named "Peter A Olubambi"

In the quest for materials that can withstand the rigors of modern engineering applications, high-entropy alloys (HEAs) have emerged as a frontier in material science owing to their unprecedented combination of properties. This review focuses on intricate thermodynamic and computational modeling to guide the design and optimization of HEAs. By dissecting the foundational "four core effects" intrinsic to HEAs-high entropy, sluggish diffusion, severe lattice distortion, and cocktail effect-we illuminate the path towards predictable and tailored material properties.

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In recent times, many investigators have delved into plastic waste (PW) research, both locally and internationally. Many of these studies have focused on problems related to land-based and marine-based PW management with its attendant impact on public health and the ecosystem. Hitherto, there have been little or no studies on forecasting PW quantities in developing countries (DCs).

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Spark plasma sintering (SPS) technique was employed in the consolidation of CrMnNiCuNbCo high entropy alloy (HEA) reinforced aluminium matrix composites. Phase stability and prediction expressions were used in the determination of the powder combination for the HEA. The microstructural analysis showed that an interdiffusion layer was formed between the aluminium matrix and the HEA particles in the sintered composites.

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The effect of mechanical alloying on the development of Ni-Al-Ti-Mn-Co-Fe-Cr high entropy alloys (HEAs) utilizing the spark plasma sintering (SPS) method is the main goal of this study. A bulk sample was fabricated using SPS after the alloys were mixed for 12 h. Thermodynamic simulation, X-ray diffraction, scanning electron microscopy, nanoindentation, and microhardness were used to investigate the microstructure and mechanical properties of the as-mixed powders.

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The nanohardness, elastic modulus, anti-wear, and deformability characteristics of TiAl-TaN composites containing 0, 2, 4, 6, 8, and 10 wt.% of TaN were investigated via nanoindentation technique in the present study. The TiAl-TaN composites were successfully fabricated via the spark plasma sintering technique (SPS).

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Nanostructured materials (NsM) are typical materials with structural length scales of one, two, or three dimensions in the range of 1-100 nm. In the development of NsM, the microstructure of a material, which is an integral factor in determining the intrinsic performance of a material, is susceptible to changes that may hinder the desired nano-state properties under different processing routes and associated varying processing parameters. NsM exhibits distinct superior properties when compared to conventional coarse-structured materials.

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The isothermal heat treatment process has been identified as a unique process of fabricating exceptional graphite cast iron due to its remarkable mechanical properties, such as excellent machinability, toughness, and high level of ultimate tensile strength. Austempered ductile iron (ADI), ductile iron (DI), and gray cast iron (GCI), known as spheroidal cast irons, are viable alternative materials compared to traditional steel casting, as well as aluminum casting. The graphite nodules from the microstructures of DI, ADI, and GCI are consistently encompassed by acicular ferrite and carbon-saturated austenite in the matrix, forming a distinctive ausferritic structure.

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The development of materials for biomedical, aerospace, and automobile industries has been a significant area of research in recent years. Various metallic materials, including steels, cast iron, nickel-based alloys, and other metals with exceptional mechanical properties, have been reportedly utilized for fabrication in these industries. However, titanium and its alloys have proven to be outstanding due to their enhanced properties.

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DFT calculations using Material Studio (2019) were used to ascertain the changes in electronic properties of recycled expanded polystyrene (rEPS) after modification with nanoparticles of ZnS and ZnO. The nanocomposites were obtained using rEPS and suitable metal salt precursors via a solvothermal method. The XRD analysis was conducted to obtain the crystallography data of the new rEPS-based nanocomposites.

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Nanoindentation is a viable method to assess the mechanical properties of developed alloys and composites at the nanometer scale without hampering the microstructure and integrity of materials. In this study, nondestructive measurement was conducted on spark plasma sintered nickel aluminium bronze (NAB), and graphene nanoplatelets (1, 2, 3 wt.%) reinforced NAB composites using the nanoindentation technique.

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Various electrochemical methods were used to understand the behavior of steel buried in unsaturated artificial soil in the presence of cathodic protection (CP) applied at polarization levels corresponding to correct CP or overprotection. Carbon steel coupons were buried for 90 days, and the steel/electrolyte interface was studied at various exposure times. The coupons remained at open circuit potential (OCP) for the first seven days before CP was applied at potentials of -1.

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This study investigates the effect of different surfactant-dispersed graphene nanofluid on the electrochemical behavior of copper. This study was achieved by measuring the open circuit potential and potentiodynamic polarization of copper in the nanofluids at room temperature. The test media includes surfactant-free graphene nanofluid and graphene nanofluid dispersed using four different surfactants, which are sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, Gum Arabic, and Tween 80.

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Recently, the issues of land-based plastics and their associated challenges in the marine world have been widely publicised in the media and scientific literature. Thus far, despite these communications, there have been few reports that have focused on the issues that acute plastic waste generation and its poor management pose to human health and the global environment. Also, articles on ways to mitigate these issues particularly in sub-Saharan Africa have not been documented.

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The major objective of this work is to study the hardness data at the domain of ferrite and Austenite phases. Nanoindentation and microhardness study has been conducted on austenite and ferrite present in the microstructure of hot rolled and heat treated duplex stainless steel (2205 DSS). Furthermore, Optical microscopy and field emission scanning electron microscope (FE-SEM) were used to identify the microstructural distribution and phases present.

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Fretting corrosion is a critical challenge in the design of hip prosthesis used in total hip arthroplasty (THA) surgeries. Currently, the design of hip implants includes a tapered junction which introduces additional interfaces that connect different parts of the hip implant such as the femoral neck and head or stem and neck interface. Micro motions that occur under the influence of load, together with chemical changes in the host environment, make these interfaces susceptible to tribocorrosion processes, particularly fretting corrosion.

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