Research Publications/Outputs

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Browsing Research Publications/Outputs by browse.metadata.impactarea "Advanced Materials Engineering"

Now showing 1 - 5 of 5
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    Influence of SN on the microstructure and mechanical properties of TI-MO-NB alloys for orthopaedic applications
    (2022-11) Muchavi, Noluntu S; Raganya, Mampai L; Machaka, R; Motsi, Glenda T; Makhatha, E
    Metastable ß-Ti alloys intended for orthopaedic implants typically possess undesirable a', a", precipitates, which increase the elastic modulus. Non-toxic Sn was reported as an effective suppressor of a', a" and precipitates. Furthermore, increasing Sn content was reported to decrease the elastic modulus. In this study, the cluster plus glue atom (CPGA) model was used to develop structurally stable ß-Ti alloys through the addition of Sn. Arc melting was conducted to fabricate the alloys. The effect of substituting Mo atoms with 0.4 and 0.5 Sn atoms on the microstructure and mechanical properties of [(Mo,Sn)(Ti)14](Nb)1 alloys was investigated. The microstructure of the alloys exhibited large equiaxed beta grains with the [(Mo0.6Sn0.4)(Ti)14](Nb)1 and [(Mo0.5Sn0.5)(Ti)14](Nb)1 alloys showing substructures. The XRD results showed that the alloys consisted of the ß phase; however, the presence of a” was observed in the [(Mo0.6Sn0.4)(Ti)14](Nb)1 alloy. The study showed that substitution of 0.5 Mo atoms with 0.5 atoms of Sn to form the [(Mo0.5Sn0.5)(Ti)14](Nb)1 cluster resulted in an elastic modulus of 49 GPa.
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    Machine learning-based prediction of phases in high-entropy alloys: A data article
    (2021-10) Machaka, Ronald; Motsi, Glenda T; Raganya, Mampai L; Radingoana, Precious M; Chikosha, Silethelwe
    A systematic framework for choosing the most determinant combination of predictor features and solving the multiclass phase classification problem associated with high-entropy alloy (HEA) was recently proposed [1]. The data associated with that research paper, titled “Machine learning-based prediction of phases in high-entropy alloys”, is presented in this data article. This dataset is a systematic documentation and comprehensive survey of experimentally reported HEA microstructures. It contains microstructural phase experimental observations and metallurgy-specific features as introduced and reported in peer-reviewed research articles. The dataset is provided with this article as a supplementary file. Since the dataset was collected from experimental peer-reviewed articles, these data can provide insights into the microstructural characteristics of HEAs, can be used to improve the optimization HEA phases, and have an important role in machine learning, material informatics, as well as in other fields.
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    Microstructures and thermal behaviour of Ti31.75V18.25Pt50 and Ti25V25Pt50 potential shape memory alloys
    (2022-11) Motsai, Tebogo M; Makhatha, ME; Camagu, Sigqibo T; Machio, Christopher N; Daswa, Pfarelo; Radingoana, Precious M; Motsi, Glenda T
    The binary Ti50Pt50 alloy exhibits high transformation temperatures (1050°C) and has gained a great deal of attention due to its potential for high temperature applications in the automotive and aerospace industries. However, this binary system has negligible shape memory effect. Shape memory effect is the property of a material to recover to its initial shape following heating while retaining residual deformations throughout an inelastic loading/unloading cycle. Improved shape memory properties could be achieved by ternary alloying Ti50Pt50. A study reported on partial substitution of Ti with 6.25 and 12.5 at. % V in the equi-atomic TiPt resulted in increased austenite and martensitic transformation temperature. This study is a follow-up to investigate the impact of higher V contents (18.25 and 25 at. %) on microstructures and the thermal behaviour of the alloys. Samples were prepared by arc melting of blended powders, and characterised for microstructures, thermal behaviour and hardness. The as-cast microstructure of Ti31.75V18.25Pt50 revealed a matrix of a single phase (Ti, V) Pt and second phases comprising TiO and (Ti2O) + Pt, while that of Ti25V25Pt50 showed a matrix of (Ti,V) Pt with TiO and Ti2O. Solution heat-treated Ti31.75V18.25Pt50 showed a matrix of the single phase (Ti, V) Pt with second phases of (Ti, V) Pt, while Ti25V25Pt50 showed a matrix of (Ti, V) Pt with second phases of (Ti, V) Pt, TiO, TiO2 and Ti2O. Increasing vanadium from 18.25 to 25 at. % led to a decrease in transformation temperature in both the as-cast and solution heat-treated conditions. The transformation temperature increased after solution heat treatment. The enthalpy change during transformation ( H) decreased with higher vanadium content. Hardness values increased with vanadium content increase in both as-cast and heat-treated conditions.
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    Process and materials design for laser cladded inconel-625/tungsten carbide wear-resistant composite coatings
    (2022-06) Olakanm, EO; Hoosain, Shaik E; Lawal, SA; Pityana, Sisa L
    Tailoring materials’ microstructural characteristics to meet mechanical functional requirements is quite critical in designing wear resistant coatings. To the best of our knowledge, no study had related carbide dissolution ratio (CDR) in laser cladded (LC) Inconel 625 coating and its microstructural parameters to its wear performance. Hence, this study explores how laser processing and materials parameters influence CDR, microhardness (MH) and volume of materials loss (VML) of fiber-laser deposited Inconel 625 composite coatings reinforced with tungsten carbide (WC-86) by employing response surface methodology (RSM) via central composite design (CCD). Furthermore, the nature of inter-relationship between the CDR in laser cladded Inconel 625 composite coatings, microstructural parameters (average mean free path and size of retained particles, and MH) as well as VML was explored to determine appropriate process and materials parameters to optimise the wear resistance of the coatings. A fully consolidated composite coating characterised with uniformly distributed retained WC86 particle size of 40 m; mean free path of 30 m within the Inconel 625 matrix; MH = 852 HV0.5; CDR = 77.08% has the most desirable wear resistance (VML = 9.42mm3 ) when processed with appropriate laser energy density (19.70 J/mm2), inconel content (70wt%) and shielding gas flow rates (6.00 l/min). This study provides new insight, for coating manufacturers, on how CDR and microstructural parameters can be manipulated as LC process and materials variables are altered with a view to designing most desirable wear resistant composite coating.
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    Spheroidisation of stainless steel powder for additive manufacturing
    (2021-06) Chikosha, Silethelwe; Tshabalala, Lerato C; Bissett, H; Lesufi, M; Mnguni, Khulekani N; Motsai, Tebogo M; Manama, T; Hoosain, S
    In additive manufacturing, powder characteristics play an important role in terms of flowability and densification, which can be improved by the use of spherical powders. In this study, irregular powder was spheroidised by plasma treatment, and the powder properties were measured. Powder characterisation was conducted to determine the morphology, particle size and distribution as well as the flowability. Spherical AISI 304 stainless steel powders were produced by plasma spheroidization, and the efficiency of the spheroidisation process was evaluated. The spheroidisation process resulted in 93% efficiency with a decrease of fine particles (<63 µm) by 22%, while the all the flowability parameters of the powder improved significantly.