BURA Collection: BCAST is striving for international excellence on both fundamental and applied research on solidification of metallic materials. BCAST sees itself as a reliable source of both new knowledge and new solidification technologies for the metallurgical industry.BCAST is striving for international excellence on both fundamental and applied research on solidification of metallic materials. BCAST sees itself as a reliable source of both new knowledge and new solidification technologies for the metallurgical industry.http://bura.brunel.ac.uk/handle/2438/1552024-03-28T17:37:30Z2024-03-28T17:37:30ZMicrostructural evolution and strengthening mechanisms of a high-strength Al-Mg-Si alloy processed by laser powder bed fusion and ageing treatmentWen, TWang, JLi, ZYang, FLiu, ZYang, HJi, Shttp://bura.brunel.ac.uk/handle/2438/285512024-03-17T03:01:34Z2024-02-10T00:00:00ZTitle: Microstructural evolution and strengthening mechanisms of a high-strength Al-Mg-Si alloy processed by laser powder bed fusion and ageing treatment
Authors: Wen, T; Wang, J; Li, Z; Yang, F; Liu, Z; Yang, H; Ji, S
Abstract: In this work, the processability, microstructural evolution and mechanical properties of a novel crack-free Al-5.3 wt% Mg-3.3 wt% Si alloy fabricated by laser powder bed fusion (LPBF) were investigated systematically. The Al-5.3 wt% Mg-3.3 wt% Si alloy with low solidification range exhibits good processability and reaches a high relative density of 99.6% at the VED of 103.3 J/mm3. The hierarchical microstructure was featured by the fine α-Al matrix that contains the interaction between the nanosized Mg2Si eutectic and high-density dislocations in the as-LPBFed alloy, which delivers high yield strength of 374 MPa and elongation of 5.8% under as-LPBFed condition. The yield strength is further enhanced to 433 MPa under as-aged condition of 180 °C for 6 h. The property enhancement is associated with the precipitation of β'′ and β phase. However, the broken and coarsened Mg2Si eutectics as well as the reduction of dislocation density result in strength degradation after ageing exceeds 300 °C.
Description: Data availability:
Data will be made available on request.2024-02-10T00:00:00ZMicrostructure and Tensile Properties of HPDC Mg–RE Alloys with Varying Y AdditionsFeng, LDong, XCai, QJi, Shttp://bura.brunel.ac.uk/handle/2438/284992024-03-09T03:01:41Z2024-02-19T00:00:00ZTitle: 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 nucleationMen, Hhttp://bura.brunel.ac.uk/handle/2438/284692024-03-05T07:58:58Z2024-03-07T00:00:00ZTitle: 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 .2024-03-07T00:00:00ZRecycling-Oriented Design of the Al-Zn-Mg-Ca AlloysShurkin, PBelov, NAkopyan, TKarpova, Zhttp://bura.brunel.ac.uk/handle/2438/284192024-02-28T03:01:43Z2021-02-18T00:00:00ZTitle: Recycling-Oriented Design of the Al-Zn-Mg-Ca Alloys
Authors: Shurkin, P; Belov, N; Akopyan, T; Karpova, Z
Abstract: Approaches to the design of recycling-tolerant Al-Zn-Mg alloys were formulated to be achieved via combined Ca, Fe, and Si, and appropriate solidification conditions and heat treatment. A CalPhaD calculation and experimental study were employed for analysis of the Al-8%Zn-3%Mg alloy doped with 1–2%Ca, 0.5%Fe, and 0.5%Si. The Al-8%Zn-3%Mg-1%Ca-0.5%Fe-0.5%Si (AlZnMg1CaFeSi) alloy was preliminarily found to be promising since it showed a high equilibrium solidus, and an as-cast structure including curved phases (Al), Al3Fe, Al2CaSi2, Al10CaFe2, and (Al, Zn)4Ca; favouring a further spheroidization response during a two-step annealing at 450 °C, 3 h + 520 °C, 3 h. Furthermore, the alloy showed an excellent age-hardening response (195 HV, T6), which did not yield the values of the base alloy and outperformed the values of the other experimental counterparts. Regarding feasibility, 80% reduction hot rolling was successfully conducted, as well as a brief comparison with commercial 6063 impurity-tolerant alloys. As it showed qualitatively similar structural patterns and Fe and Si alloying opportunities, the AlZnMg1CaFeSi alloy may serve as a sustainable basis for the further development of high-strength aluminum alloys tailored for manufacture from scrap materials.
Description: Presented at the 1st International Electronic Conference on Metallurgy and Metals, 22 February–7 March 2021; Available online: https://iec2m.sciforum.net/.2021-02-18T00:00:00Z