Browsing by Author "Liao, XZ"
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- ItemAdditively manufactured Haynes-282 monoliths containing thin wall struts of varying thicknesses(Elsevier, 2022-09-01) Lim, B; Chen, H; Nomoto, K; Chen, Z; Saville, AI; Vogel, SC; Clarke, AJ; Paradowska, AM; Reid, M; Primig, S; Liao, XZ; Babu, SS; Breen, AJ; Ringer, SPMagnitude and distribution of residual stresses in additively manufactured Ni-based superalloys may impact the mechanical performance of as-fabricated parts. Though electron beam powder bed fusion (E-PBF) can produce components with minimal defects and residual stresses compared to laser powder bed fusion and directed energy deposition, variations of them may occur within the complex geometry of a component, due to inherent variations of thermal signatures and the evolution of section modulus along the build direction. This work reveals the residual stress distribution, characterised from neutron diffraction, of an as-fabricated Haynes 282 monolith containing internal cube voids and thin wall struts of varying thicknesses. Complementary local hardness measurements and multi-scale microscopy were used to investigate the geometry-structure-property relationships. Observed variations in hardness were attributed to a combination of type I macro-scale residual stresses and variations in bimodal γ′ precipitation behaviour. The results highlight the influence of residual stresses and microstructure on the mechanical properties of E-PBF Haynes 282. © 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
- ItemHydrogen-induced microstructure, texture and mechanical property evolutions in a high-pressure torsion processed zirconium alloy(Elsevier Ltd., 2012-11-01) Wang, ZY; Garbe, U; Li, HJ; Studer, AJ; Harrison, RP; Callaghan, MD; Wang, Y; Liao, XZThe gaseous hydriding-induced evolutions of the microstructure, texture and mechanical properties of Zircaloy-4 processed by high-pressure torsion (HPT) were assessed. Much delta-ZrH(1.66) precipitation at 15 atm (21%) incurred significant hardening of vacuum-annealed HPT samples, and pure epsilon-ZrH(2) obtained at 20 atm showed a superior microhardness of 470 HV(0.3) and a low fracture toughness of 0.63 MPa m(1/2). The delta-hydrides presented strong (1 1 1) texture and followed the (0 0 0 1)(alpha-Zr)//{1 1 1}(delta-ZrH1.66) orientation relationship with the alpha-Zr matrix. During hydriding, alpha-Zr recrystallization texture was developed from the initial deformation texture. Copyright © 2012 Acta Materialia Inc.
- ItemMartensitic phase transformation and deformation behavior of Fe–Mn–C–Al twinning-induced plasticity steel during high-pressure torsion(Wiley Online Library, 2014-02-05) Yan, K; Bhattacharyya, D; Lian, Q; Kabra, S; Kawasaki, M; Carr, DG; Callaghan, MD; Avdeev, M; Li, HJ; Wang, Y; Liao, XZ; Langdon, TG; Liss, KD; Dippenaar, RJThe transformation between the face centered cubic austenitic and hexagonal close-packed martensitic phases during high-pressure torsion processing was observed in a Fe–Mn–C–Al twinning-induced plasticity steel. This phase transformation was not found in the same material processed by unidirectional compressive and tensile deformation. Initiated by the high-pressure loading, the martensite phase initially increased with torsional strain but diminished subsequently. Texture evolution of the austenitic phase was compared with the ideal texture distribution of face-centered cubic materials after shear deformation.© 2014, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
- ItemMicrostructural evolution during gaseous hydrogen charging of Zircaloy-4 processed by high-pressure torsion: a comparative study(Elsevier B.V., 2012-02-01) Wang, ZY; Li, HJ; Garbe, U; Callaghan, MD; Wang, Y; Liao, XZThe original and high-pressure torsion (HPT) processed Zircaloy-4 materials were hydrided using gaseous hydrogen charging at different hydrogen pressures (10, 15 and 20 atm). The phase and microstructural evolutions of the samples during hydriding were characterized. It showed that when hydriding at the identical conditions, more hydrides tended to form in the HPT samples compared to that of the original ones. At a hydrogen pressure of 20 atm, the HPT sample was completely converted to epsilon-ZrH2 while some delta-ZrH1.66 hydrides (volume fraction similar to 5.73%) were present in the material without HPT preprocessing. The HPT samples exhibited high potential for the hydride precipitation, and the large concentration of lattice defects induced by HPT was considered to be responsible for this enhanced susceptibility. © 2011 Elsevier B.V.
- ItemMicrostructure and texture analysis of δ-hydride precipitation in Zircaloy-4 materials by electron microscopy and neutron diffraction(International Union of Crystallography, 2014-01-01) Wang, ZY; Garbe, U; Li, HJ; Wang, YB; Studer, AJ; Sun, GG; Harrison, RP; Liao, XZ; Vicente Alvarez, MA; Santisteban, JR; Kong, CThis work presents a detailed microstructure and texture study of various hydrided Zircaloy-4 materials by neutron diffraction and microscopy. The results show that the precipitated δ-ZrH1.66 generally follows the δ (111)//α(0001) and δ [110]//α[1120] orientation relationship with the α -Zr matrix. The δ-hydride displays a weak texture that is determined by the texture of the α-Zr matrix, and this dependence essentially originates from the observed orientation correlation between α-Zr and δ-hydride. Neutron diffraction line profile analysis and high-resolution transmission electron microscopy observations reveal a significant number of dislocations present in the δ-hydride, with an estimated average density one order of magnitude higher than that in the α-Zr matrix, which contributes to the accommodation of the substantial misfit strains associated with hydride precipitation in the α -Zr matrix. The present observations provide an insight into the behaviour of δ-hydride precipitation in zirconium alloys and may help with understanding the induced embrittling effect of hydrides.© 2014 International Union of Crystallography.
- ItemOn the atomic anisotropy of thermal expansion in bulk metallic glass(Wiley-Blackwell, 2011-09-01) Qu, DD; Liss, KD; Yan, K; Reid, M; Almer, JD; Wang, Y; Liao, XZ; Shen, JGlass transition temperature and plastic yield strength are known to be correlated in metallic glasses. We have observed by in situ synchrotron high energy X-ray diffraction anisotropy of the thermal expansion behavior in the nearest neighbor and second nearest neighbor atomic distances in the building blocks of Zr-Cu-Ni-Al based bulk metallic glass, leading inevitably to shear. Mechanical yielding of the latter on the atomic scale leads to the glass transition and the increase of the free volume. These experimental results uncover the mechanism, how glass transition and yield strength are linked. © 2011, Wiley-Blackwell.
- ItemStructural origins for the high plasticity of a Zr-Cu-Ni-Al bulk metallic glass(Pergamon-Elsevier Science Ltd, 2012-09-11) Qu, DD; Liss, KD; Sun, YJ; Reid, M; Almer, JD; Yan, K; Wang, Y; Liao, XZ; Shen, JThe structural origins for the high plasticity of a Zr(53)Cu(18.7)Ni(12)Al(16.3) (at.%) bulk metallic glass are explored. Under plastic flow conditions, in situ synchrotron high-energy X-ray diffraction reveals that the atomic strain saturates to the closest packing in the longitudinal direction of the applied load while atoms yield in the transverse plane. Scanning electron microscopy investigation reveals that global plasticity benefits from abundant shear band multiplication and interactions. Atomic level flows are seen to accompany profuse shear bands. The plasticity enhancement of this metallic glass benefits from such atomic level flows. Atomic level flow facilitates the activation of shear transformation zones that further self-assemble to promote shear band multiplication. On the other hand, it also mitigates the shear band propagation that prevents catastrophic shear band extension. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. © 2012, Elsevier Ltd.