BURA Community:
http://bura.brunel.ac.uk/handle/2438/22
2024-03-15T09:21:14ZMicrostructure and Tensile Properties of HPDC Mg–RE Alloys with Varying Y Additions
http://bura.brunel.ac.uk/handle/2438/28499
Title: Microstructure and Tensile Properties of HPDC Mg–RE Alloys with Varying Y Additions
Authors: Feng, L; Dong, X; Cai, Q; Ji, S
Abstract: High-pressure die-casting Mg–2.6RE–xY (EW) alloys with Y contents between 0 and 3% (in wt%) were investigated for their microstructure and tensile properties. In the Y-containing alloy, the intermetallic phases at the grain boundaries consisted of skeletal Mg12RE phase, bulk Mg24Y5 phase and irregular Mg3Y phase, while {011} twins were observed in the Mg12RE phase. The yield strength was improved by Y addition at both room temperature and high temperatures. Compared with Y-free alloy, the yield strength of 3% Y alloy increased from 143.1 to 174.8 MPa and improved by 22.2% at room temperature, while it was increased from 72.2 to 104.6 MPa and enhanced by 44.9% at 300 °C. The area fraction of intermetallic phase increased dramatically from 14.5 to 18.4% with 3% Y addition. Second phase strengthening was the major contributor to the yield strength increase at ambient temperature. The increment of the area fraction of the high-thermally stable Mg–RE intermetallic phases with Y addition contributed to the consequent improvement in yield strength at high temperatures. At ambient temperature, the mechanism for the fracture of EW alloys was a ductile and quasi-cleavage fracture blend.
Description: This paper is an invited submission to IJMC selected from presentations at the Light Metals Technology Conference (LMT2023) held July 10 to 12, 2023, in Melbourne, Australia, based upon the original presentation.; Supplementary Information is available online at: https://link.springer.com/article/10.1007/s40962-024-01266-z#Sec17 .2024-02-19T00:00:00ZA molecular dynamics study on the boundary between homogeneous and heterogeneous nucleation
http://bura.brunel.ac.uk/handle/2438/28469
Title: A molecular dynamics study on the boundary between homogeneous and heterogeneous nucleation
Authors: Men, H
Abstract: The large discrepancy among the nucleation kinetics extracted from experimental measurements and computer simulations and the prediction of the classical nucleation theory (CNT) has stimulated intense arguments about its origin in the past decades, which is crucially relevant to the validity of the CNT. In this paper, we investigate the atomistic mechanism of the nucleation in liquid Al in contact with amorphous substrates with atomic-level smooth/rough surfaces, using molecular dynamics (MD) simulations. This study reveals that the slightly distorted local fcc/hcp structures in amorphous substrates with smooth surfaces can promote heterogeneous nucleation through a structural templating mechanism, and on the other hand, homogeneous nucleation will occur at a larger undercooling through a fluctuation mechanism if the surface is rough. Thus, some impurities, previously thought to be impotent, could be activated in the homogeneous nucleation experiments. We further find that the initial growth of the nucleus on smooth surfaces of amorphous substrates is one order of magnitude faster than that in homogeneous nucleation. Both these factors could significantly contribute to the discrepancy in the nucleation kinetics. This study is also supported by a recent study of the synthesis of high-entropy alloy nanoparticles assisted with the liquid metal Ga [Cao et al., Nature 619, 73 (2023)]. In this study, we established that the boundary existed between homogeneous and heterogeneous nucleation, i.e., the structural templating is a general mechanism for heterogeneous nucleation, and in its absence, homogeneous nucleation will occur through the fluctuation mechanism. This study provides an in-depth understanding of the nucleation theory and experiments.
Description: Data Availability: The data that support the findings of this study are available within the article.; Supplementary material: The supplementary material is available online at:
https://pubs.aip.org/jcp/article-supplement/3267965/zip/094702_1_5.0192069.suppl_material .2024-03-07T00:00:00ZControlled Synthesis of Chromium-Oxide-Based Protective Layers on Pt: Influence of Layer Thickness on Selectivity
http://bura.brunel.ac.uk/handle/2438/28463
Title: Controlled Synthesis of Chromium-Oxide-Based Protective Layers on Pt: Influence of Layer Thickness on Selectivity
Authors: Worsley, M; Smulders, V; Mei, B
Abstract: Chromium-oxyhydroxide (CrxOyHz)-based thin films have previously been shown in photocatalysis and industrial chlorate production to prevent unwanted reduction reactions to occur, thereby enhancing the selectivity for hydrogen evolution and thus the overall process efficiency. Here, a highly reproducible synthesis protocol was developed to allow for the electrodeposition of CrxOyHz-based thin films with controlled thickness in the range of the sub-monolayer up to (>4) multilayer coverage. Electrodeposited CrxOyHz coatings were electrochemically characterized using voltammetry and stripping experiments, allowing thickness-dependent film selectivity to be deduced in detail. The results are discussed in terms of mass transport properties and structure of the electrodeposited chromium oxyhydroxide films. It is shown that the permeation of diatomic probe molecules, such as O2 and CO, was significantly reduced by films as thin as four monolayers. Importantly, it is shown that the prepared thin film coatings enabled prolonged hydrogen oxidation in the presence of CO (up to 5 vol.%), demonstrating the benefits of thin-film-protected electrocatalysts. In general, this study provides insight into the synthesis and use of thin-film-protected electrodes leading to improvements in (electro)catalyst selectivity and durability.
Description: Data Availability Statement
The data presented in this study are available in Supplementary Material available online at: https://www.mdpi.com/2073-4344/12/10/1077#app1-catalysts-12-01077 .2022-09-20T00:00:00ZMechanical Properties of Bio-Based Sandwich Composites Containing Recycled Polymer Textiles
http://bura.brunel.ac.uk/handle/2438/28459
Title: Mechanical Properties of Bio-Based Sandwich Composites Containing Recycled Polymer Textiles
Authors: Khalili, P; Skrifvars, M; Dhakal, HN; Dashatan, SH; Danielsson, M; Gràcia, AF
Abstract: In this paper, sandwich composites were produced by compression moulding techniques, and they consisted of regenerated cellulose fabric (rayon) and bio-based polypropylene (PP) to form facings, while virgin and recycled polyamide (PA) textiles were used as core materials. To compare the mechanical performance between sandwich composites and typical composite designs, a control composite was produced to deliver the same weight and fiber mass fraction from rayon and PP. To evaluate the influence of recycled textile on the mechanical properties of the composites, a series of flexural, low velocity impact (LVI) and tensile tests were performed. It was found that the incorporation of thicker PA textile enhanced the bending stiffness by two times and the peak flexural force by 70% as compared to those of control. Substitution of a layer of recycled textile for two layers of rayon provided a good level of impact energy absorption capacity (~28 J) and maximum force (~4893–5229 N). The tensile strength of the four sandwich composites was reported to be in the range of 34.20 MPa and 46.80 MPa. This value was 91.90 for the control composite. The 2D cross-section slices of the composite specimens did not show any evidence of fiber tow debonding, fiber bundle splitting, or delamination.
Description: Data Availability Statement:
Data are available upon request.2023-09-19T00:00:00Z