ORCID Profile
0000-0003-1626-3748
Current Organisation
Curtin University
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Publisher: Trans Tech Publications, Ltd.
Date: 15-11-2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.879.350
Abstract: In this study the effects of heating rate on the sharpness and size of Goss oriented ({110} ) grains during secondary recrystallization annealing at 900 °C was observed. The results show that, at the same annealing temperature, rapid heating of the s les to this temperature generates a higher drag force compared to a slower heating rate (5°C/min). The two groups of s les show different growth kinetics for Goss grains, in which at the longest annealing time, the rapid heating s le exhibits larger maximum Goss grain size compared to the slower heated s les.
Publisher: Elsevier BV
Date: 07-2013
Publisher: MDPI AG
Date: 31-05-2021
DOI: 10.3390/MIN11060590
Abstract: Acid mine drainage (AMD) is a serious environmental issue associated with mining due to its acidic pH and potentially toxic elements (PTE) content. This study investigated the performance of the Fe-Al bimetallic particles for the treatment of combined AMD-gold processing effluents. Batch experiments were conducted in order to eliminate potentially toxic elements (including Hg, As, Cu, Pb, Ni, Zn, and Mn) from a simulated waste solution at various bimetal dosages (5, 10, and 20 g/L) and time intervals (0 to 90 min). The findings show that metal ions with greater electrode potentials than Fe and Al have higher affinities for electrons released from the bimetal. Therefore, a high removal ( %) was obtained for Hg, As, Cu, and Pb using 20 g/L bimetal in 90 min. Higher uptakes of Hg, As, Cu, and Pb than Ni, Zn, and Mn also suggest that electrochemical reduction and adsorption by Fe-Al (oxy) hydroxides as the primary and secondary removal mechanisms, respectively. The total Al3+ dissolution in the experiments with a higher bimetal content (10 and 20 g/L) were insignificant, while a high release of Fe ions was recorded for various bimetal dosages. Although the secondary Fe pollution can be considered as a drawback of using the Fe-Al bimetal, this issue can be tackled by a simple neutralization and Fe precipitation process. A rapid increase in the solution pH (initial pH 2 to in 90 min) was also observed, which means that bimetallic particles can act as a neutralizing agent in AMD treatment system and promote the precipitation of the dissolved metals. The presence of chloride ions in the system may cause akaganeite formation, which has shown a high removal capacity for PTE. Moreover, nitrate ions may affect the process by competing for the released electrons from the bimetal owing to their higher electrode potential than the metals. Finally, the Fe-Al bimetallic material showed promising results for AMD remediation by electrochemical reduction of PTE content, as well as acid-neutralization/metal precipitation.
Publisher: Trans Tech Publications, Ltd.
Date: 12-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.702-703.558
Abstract: There are two opposing theories regarding the nature of aligned dislocation boundaries generated during plastic deformation of FCC metals: (i) they are oriented along crystallographic planes, and (ii) their alignment is dictated by the macroscopic stress state during plastic deformation. 3D crystallographic orientation data were collected on a volume containing microbands in commercial purity aluminum, and 3D boundaries were reconstructed. Both types of alignment were found in local surface features.
Publisher: Springer Science and Business Media LLC
Date: 21-08-2021
Publisher: Author(s)
Date: 2018
DOI: 10.1063/1.5044817
Publisher: Springer Science and Business Media LLC
Date: 25-06-2019
Publisher: Springer International Publishing
Date: 2016
Publisher: Elsevier BV
Date: 05-2013
Publisher: Elsevier BV
Date: 06-2011
Publisher: Elsevier BV
Date: 2009
Publisher: Trans Tech Publications, Ltd.
Date: 12-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.702-703.161
Abstract: Lamellar bands are the primary structural features in accumulative roll bonding (ARB) of sheet metals. The structural refinement in ARB sheets occur by forming a dense distribution of lamellar band boundaries. The lamellar band boundaries initiate as low angle interfaces, parallel to the existing lamellar band boundaries, irrespective of the crystallographic orientations of the parent lamellar bands. From an extensive investigation it was found that the transverse directions across the lamellar band boundaries are rotated by an angle equal to their misorientations. Such a phenomenon is not sustained when the boundaries turn to high angle.
Publisher: Elsevier BV
Date: 08-2018
Publisher: Association for Materials Protection and Performance (AMPP)
Date: 04-03-2022
DOI: 10.5006/3999
Abstract: Selective laser melting (SLM) or powder bed fusion is a type of additive manufacturing technology with applications in, e.g., the orthopedics, energy, and aerospace industries. Several studies investigated the localized corrosion behavior of SLM-fabricated Type 316L (UNS S31603) stainless steel. However, little is known about the effects of tribocorrosive conditions on the response of stainless steels fabricated by SLM. In this study, the effects of third-body abrasive particles on the tribo-electrochemical behavior of SLM 316L stainless steel produced by SLM were investigated and compared with wrought counterparts (including UNS S31703, 317W) in 0.6 M NaCl. It was found that the presence of Mo played a more decisive role in the tribocorrosion behavior than the manufacturing method, i.e., 317W revealed the best tribocorrosion behavior vis-a-vis wrought 316L and the SLM-fabricated specimens. The improved tribocorrosion behavior contrasted with the much higher breakdown potential of the SLM-fabricated s les. Nano-scale secondary ion mass spectroscopy was used to investigate the effects of Mo on passivity. The implications of passivity and tribocorrosion behavior are discussed.
Publisher: Elsevier BV
Date: 02-2011
Publisher: American Association for the Advancement of Science (AAAS)
Date: 04-06-2021
Abstract: Spinodal decomposition is discovered to be an effective way to strengthen magnesium alloy.
Publisher: Mineralogical Society of America
Date: 08-2022
DOI: 10.2138/AM-2021-7866
Abstract: Seafloor hydrothermal chimneys from back-arc basins are important hosts for metals such as Cu, Zn, Pb, Ag, and Au. Although the general growth history of chimneys has been well documented, recent studies have revealed that the fine-scale mineralogy can be highly complex and reflects variable physicochemical conditions of formation. This study utilized a novel combination of scanning electron microscopy (SEM)-based electron backscattered diffraction (EBSD) and synchrotron X-ray fluorescence microscopy (SXFM) to uncover the detailed growth processes of multiple chalcopyrite-lined conduits within a modern chalcopyrite-sphalerite chimney from Manus Basin and to assess the controls on native gold precipitation. On the basis of previous studies, the chimney conduit was thought to develop from an initial sulfate-dominated wall, which was subsequently dissolved and replaced by sphalerite and chalcopyrite during gradual mixing of hydrothermal fluids and seawater. During this process, sphalerite was epitaxially overgrown by chalcopyrite. Accretionary growth of chalcopyrite onto this early formed substrate thickened the chimney walls by bi-directional growth inward and outward from the original tube wall, also enclosing the outgrown pyrite cluster. A group of similar conduits with slightly different mineral assemblages continued to form in the vicinity of the main conduit during the further fluid mixing process. Four types of distinct native gold-sulfide/sulfosalt associations were developed during the varying mixing of hydrothermal fluids and seawater. Previously unobserved chains of gold nanoparticles occur at the boundary of early sphalerite and chalcopyrite, distinct from gold observed in massive sphalerite as identified in other studies. These observations provide baseline data in a well-preserved modern system for studies of enrichment mechanisms of native gold in hydrothermal chimneys. Furthermore, native gold is relatively rarely observed in chalcopyrite-lined conduit walls. Our observations imply that: (1) native gold is closely associated with various sulfides/sulfosalts in chalcopyrite-lined conduit walls rather than limited to the association with tennantite, Bi-rich minerals, and bornite as reported previously and (2) the broad spectrum of gold occurrence in chalcopyrite-line conduits is likely to be determined by the various mixing process between hot hydrothermal fluids with surrounding fluids or seawater. Quantitative modeling of fluid mixing processes is recommended in the future to probe the precise gold deposition stages to efficiently locate gold in modern hydrothermal chimneys.
Publisher: Springer Science and Business Media LLC
Date: 03-01-2022
Publisher: Author(s)
Date: 2017
DOI: 10.1063/1.4971656
Publisher: Springer Science and Business Media LLC
Date: 28-01-2019
Publisher: Association for Materials Protection and Performance (AMPP)
Date: 03-04-2019
DOI: 10.5006/3192
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.715-716.41
Abstract: A focused ion beam (FIB) coupled with high resolution electron backscatter diffraction (EBSD) has emerged as a useful tool for generating crystallographic information in reasonably large volumes of microstructure. In principle, data generation is reasonably straightforward whereby the FIB is used as a high precision serial sectioning device for generating consecutive milled surfaces suitable for mapping by EBSD. The successive EBSD maps generated by serial sectioning are combined using various post-processing methods to generate crystallographic volumes of the microstructure. This paper provides an overview of the use of 3D-EBSD in the study of various phenomena associated with thermomechanical processing of both crystalline and semi-crystalline alloys and includes investigations on the crystallographic nature of microbands, void formation at particles, phase redistribution during plastic forming, and nucleation of recrystallization within various regions of the deformation microstructure.
Publisher: Iron and Steel Institute of Japan
Date: 2010
Publisher: Elsevier BV
Date: 09-2022
Publisher: Springer Science and Business Media LLC
Date: 29-11-2021
Publisher: Elsevier BV
Date: 02-2017
Publisher: Author(s)
Date: 2018
DOI: 10.1063/1.5044810
Publisher: Springer Science and Business Media LLC
Date: 27-12-2017
Publisher: Springer Science and Business Media LLC
Date: 03-04-2015
Publisher: Elsevier BV
Date: 08-2004
Publisher: Author(s)
Date: 2018
DOI: 10.1063/1.5044811
Publisher: Elsevier BV
Date: 08-2011
Publisher: Elsevier BV
Date: 03-2019
Publisher: Wiley
Date: 20-06-2013
Publisher: Elsevier BV
Date: 03-2016
Publisher: Elsevier BV
Date: 09-2017
Publisher: Trans Tech Publications, Ltd.
Date: 15-11-2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.879.454
Abstract: Microstructure and texture evolution of commercially pure Ni processed by accumulative roll-bonding (ARB) up to eight cycles were studied using electron back scattered diffraction (EBSD). During ARB processing, the original coarse equiaxed grains were gradually transformed into refined lamellar grains along the rolling direction (RD). Shear bands started forming after three cycles. The fraction of low angle grain boundaries (LAGBs) increased after the first and second cycle because of orientation spreading within the original grains. However, their fraction decreased with the evolution of high angle grain boundaries (HAGBs) during subsequent deformations, until saturation was reached after six cycles. Overall, the typical deformation texture components (S, Copper and Brass) were enhanced up to six ARB cycles and then only Copper was further strengthened. At higher cycles a higher Copper concentration was found near s le surface than the interiors due to a high frictional shear of ARB processing.
Publisher: Trans Tech Publications, Ltd.
Date: 12-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.667-669.481
Abstract: Sheets of commercial purity aluminum and super saturated solid solution of 0.3% Sc were accumulatively roll bonded to form 64 alternating layers in a 0.5 mm thickness. The rolling was done at 350 °C to ensure dynamic recovery/recrystallization in Al layers and precipitation hardening of Al(Sc) layers during the rolling. The sheet crystallographic texture was distributed along β fibre orientations. The recrystallization texture of aluminum layers after annealed at 250-350 °C was randomly distributed. The tensile property of this novel composite has achieved a small improvement over the commercially available grades and delamination between the layers was identified as the key issue to improve in this fabrication technique.
Publisher: Elsevier BV
Date: 2017
Publisher: Author(s)
Date: 2017
DOI: 10.1063/1.4971709
Publisher: Association for Materials Protection and Performance (AMPP)
Date: 30-05-2023
DOI: 10.5006/4311
Abstract: Austenitic stainless steel UNS S31603 (SS316L) is widely used in the resources industry due to its excellent corrosion resistance, ductility, and weldability. Recently, laser-based powder bed fusion (LPBF) manufacturing has gained popularity for creating SS316L components with complex geometries and superior mechanical properties. However, the rapid melting and solidification of the deposited layers during the thermal cycle of LPBF produce residual stresses. Components manufactured through LPBF are frequently used under applied stress in corrosive environments. Thus, it is crucial to understand their susceptibility to stress corrosion cracking (SCC) and the impact of residual stresses. This study investigated the combined effects of applied stress and temperature on the SCC behavior of LPBF SS316L using custom-made C-ring test specimens. Cold-drawn wrought SS316L was included for comparison. Stress relief heat treatment, microhardness testing, partial immersion testing, and microanalysis techniques, such as light optical microscopy, scanning electron microscopy, and electron backsacttered diffraction were used to quantify the SCC behavior. The outcomes of this study showed that stressed and unstressed LPBF SS316L specimens were highly susceptible to cracking around their printed holes. The SCC susceptibility was attributed to the residual stresses introduced by the printed supports, as both polished and as-printed holes showed similar cracking behavior. This work provides valuable insights and lays a foundation for further research into the impact of using C ring s les to investigate SCC susceptibility and sheds light on the SCC susceptibility of as-printed components of complex geometry printed with supports due to the influence of residual stresses.
Publisher: Elsevier BV
Date: 12-2007
Publisher: Springer Science and Business Media LLC
Date: 11-10-2016
DOI: 10.1038/SREP34958
Abstract: Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels’ performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano scale of the compressive stability of retained austenite in high carbon martensitic steel. Using a combination of standard compression testing, X-ray diffraction, optical microstructure, electron backscattering diffraction imaging, electron probe micro-analysis, nano-indentation and micro-indentation measurements, we determined the mechanical stability of retained austenite and martensite in high carbon steel under compressive stress and identified the phase transformation mechanism, from the macro to the nano level. We found at the early stage of plastic deformation hexagonal close-packed (HCP) martensite formation dominates, while higher compression loads trigger body-centred tetragonal (BCT) martensite formation. The combination of this phase transformation and strain hardening led to an increase in the hardness of high carbon steel of around 30%. This comprehensive characterisation of stress induced phase transformation could enable the precise control of the microstructures of high carbon martensitic steels, and hence their properties.
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 06-2008
Publisher: Informa UK Limited
Date: 11-08-2006
Publisher: Iron and Steel Institute of Japan
Date: 2017
Publisher: Elsevier BV
Date: 04-2019
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 06-2012
Publisher: Springer Science and Business Media LLC
Date: 13-03-2013
Publisher: Elsevier BV
Date: 10-2012
Publisher: Informa UK Limited
Date: 18-11-2014
Publisher: The Electrochemical Society
Date: 05-01-2020
Abstract: Super Duplex Stainless Steels (SDSS) have excellent corrosion resistance due to their high concentration of alloying elements like Cr, Mo, and N. There is still, however, disagreement on the role of tungsten in the corrosion resistance of stainless steels. In this regard, the influence of tungsten on tertiary phase precipitation kinetics remains a chief source of controversy. In this study, three different SDSS with different tungsten contents have been investigated, namely, UNS S32750 (W-free), S32760 (0.6 wt% W), and S39274 (2.1 wt% W). Different isothermal aging conditions were studied, followed by microstructure characterization using scanning electron microscopy, energy dispersive X-ray spectroscopy, electron backscatter diffraction, and transmission electron microscopy to quantify the type and volume fraction of tertiary phases and intermetallic compounds. Time-Temperature-Transformation-Corrosion maps were constructed by quantifying the changes in pitting corrosion resistance caused by the precipitation of incremental amounts of deleterious phases. Results showed that 2.1 wt% W additions retarded the precipitation kinetics of all tertiary phases—including σ -phase—favoring the formation of χ -phase. Both χ - and σ -phase affected corrosion resistance, reducing the critical pitting temperature by 10 °C–20 °C at concentrations well below 1 vol%.
Publisher: The Electrochemical Society
Date: 2019
DOI: 10.1149/2.0511913JES
Publisher: Elsevier BV
Date: 04-2016
Publisher: Springer Science and Business Media LLC
Date: 11-06-2009
Publisher: Elsevier BV
Date: 02-2020
Publisher: Mineralogical Society of America
Date: 12-2021
DOI: 10.2138/AM-2021-7654
Abstract: To evaluate the mechanisms driving nanoscale trace element mobility in radiation-damaged zircon, we analyzed two well-characterized Archean zircons from the Kaapvaal Craton (southern Africa): one zircon remained untreated and the other was experimentally heated in the laboratory at 1450 °C for 24 h. Atom probe tomography (APT) of the untreated zircon reveals homogeneously distributed trace elements. In contrast, APT of the experimentally heated zircon shows that Y, Mg, Al, and Pb+Yb segregate to a set of two morphologically and crystallographically distinct cluster populations that range from 5 nm tori to 25 nm toroidal polyhedra, which are confirmed to be dislocation loops by transmission electron microscopy (TEM). The dislocation loops lie in {100} and {001} planes the edges are aligned with & & , & & , and & & . The largest loops (up to 25 nm diameter) are located in {100} and characterized by high concentrations of Mg and Al, which are aligned with & & . The 207Pb/206Pb measured from Pb atoms located within all of the loops (0.264 ± 0.025 1σ) is consistent with present-day segregation and confirms that the dislocation loops formed during our experimental treatment. These experimentally induced loops are similar to clusters observed in zircon affected by natural geologic processes. We interpret that differences in cluster distribution, density, and composition between experimentally heated and geologically affected zircon are a function of the radiation dose, the pressure-temperature-time history, and the original composition of the zircon. These findings provide a framework for interpreting the significance of clustered trace elements and their isotopic characteristics in zircon. Our findings also suggest that the processes driving cluster formation in zircon can be replicated under laboratory conditions over human timescales, which may have practical implications for the mineralogical entrapment of significant nuclear elements.
Publisher: Elsevier BV
Date: 05-2018
Publisher: SAGE Publications
Date: 06-2004
DOI: 10.1243/095440604774202277
Abstract: To give good drawability, steel needs high volume fractions of the annealing texture component {111} 〈hkl〉 and a low fraction of ε {100} 〈0k1〉. This is achieved in conventional Nb + Ti stabilized interstitial free (IF) steels by a cold rolling (CR) reduction of 85 per cent followed by annealing at 750–850°C for a few minutes. In this research, a detailed investigation of two-stage deformation processes was undertaken in which the total reduction in thickness was kept constant at 80 per cent, with a first and second rolling interrupted by recrystallization (RX) before the final recrystallization anneal was made. The texture produced is a rather flat γ recrystallization fibre of relatively high intensity at a reasonable final grain size. A second experiment, involving rolling ferrite at 700°C, produced a strong rolling texture and a well-developed {111} 〈hkl〉 texture after annealing at 710°C, and so this material was also subjected to further rolling and annealing. The intermediate annealing between warm rolling (WR) and subsequent cold rolling significantly improved the intensity and uniformity of the final {111} texture compared with metal that was cold rolled without intermediate annealing. An investigation into the mechanisms involved in recrystallization revealed that the {111} 〈hkl〉 oriented grains were subject to orientation splitting involving rotations around 〈111〉 ND, and this process of deformation banding produced the necessary lattice curvature for nucleation of the {111} recrystallization texture components essential for good deep drawability.
Publisher: Elsevier BV
Date: 10-2016
Publisher: IOP Publishing
Date: 08-08-2014
Publisher: MDPI AG
Date: 26-05-2023
DOI: 10.3390/MA16114006
Abstract: This study investigates the stress corrosion cracking (SCC) behavior of type 316L stainless steel (SS316L) produced with sinter-based material extrusion additive manufacturing (AM). Sinter-based material extrusion AM produces SS316L with microstructures and mechanical properties comparable to its wrought counterpart in the annealed condition. However, despite extensive research on SCC of SS316L, little is known about the SCC of sinter-based AM SS316L. This study focuses on the influence of sintered microstructures on SCC initiation and crack-branching susceptibility. Custom-made C-rings were exposed to different stress levels in acidic chloride solutions at various temperatures. Solution-annealed (SA) and cold-drawn (CD) wrought SS316L were also tested to understand the SCC behavior of SS316L better. Results showed that sinter-based AM SS316L was more susceptible to SCC initiation than SA wrought SS316L but more resistant than CD wrought SS316L, as determined by the crack initiation time. Sinter-based AM SS316L showed a noticeably lower tendency for crack-branching than both wrought SS316L counterparts. The investigation was supported by comprehensive pre- and post-test microanalysis using light optical microscopy, scanning electron microscopy, electron backscatter diffraction, and micro-computed tomography.
Publisher: Elsevier BV
Date: 11-2016
Publisher: Informa UK Limited
Date: 11-02-2011
Publisher: Springer Science and Business Media LLC
Date: 03-2019
DOI: 10.1038/S41467-019-08954-Z
Abstract: Body-centred cubic magnesium-lithium-aluminium-base alloys are the lightest of all the structural alloys, with recently developed alloy compositions showing a unique multi-dimensional property profile. By hitherto unrecognised mechanisms, such alloys also exhibit exceptional immediate strengthening after solution treatment and water quenching, but strength eventually decreases during prolonged low temperature ageing. We show that such phenomena are due to the precipitation of semi-coherent D0 3 -Mg 3 Al nanoparticles during rapid cooling followed by gradual coarsening and subsequent loss of coherency. Physical explanation of these phenomena allowed the creation of an exceptionally low-density alloy that is also structurally stable by controlling the lattice mismatch and volume fraction of the Mg 3 Al nanoparticles. The outcome is one of highest specific-strength engineering alloys ever developed.
Publisher: MDPI AG
Date: 09-06-2023
DOI: 10.3390/MA16124289
Abstract: There is a fast-growing interest in the use of selective laser melting (SLM) for metal/alloy additive manufacturing. Our current knowledge of SLM-printed 316 stainless steel (SS316) is limited and sometimes appears sporadic, presumably due to the complex interdependent effects of a large number of process variables of the SLM processing. This is reflected in the discrepant findings in the crystallographic textures and microstructures in this investigation compared to those reported in the literature, which also vary among themselves. The as-printed material is macroscopically asymmetric in terms of both structure and crystallographic texture. The and crystallographic directions align parallel with the SLM scanning direction (SD) and build direction (BD), respectively. Likewise, some characteristic low-angle boundary features have been reported to be crystallographic, while this investigation unequivocally proves them to be non-crystallographic, since they always maintain an identical alignment with the SLM laser scanning direction, irrespective of the matrix material’s crystal orientation. There are also 500 ± 200 nm columnar or cellular features, depending on the cross-section, which are generally found all over the s le. These columnar or cellular features are formed with walls made of dense packing of dislocations entangled with Mn-, Si- and O-enriched amorphous inclusions. They remain stable after ASM solution treatments at a temperature of 1050 °C, and therefore, are capable of hindering boundary migration events of recrystallization and grain growth. Thus, the nanoscale structures can be retained at high temperatures. Large 2–4 μm inclusions form during the solution treatment, within which the chemical and phase distribution are heterogeneous.
Publisher: Elsevier BV
Date: 04-2016
Publisher: Elsevier BV
Date: 03-2011
Publisher: Elsevier BV
Date: 04-2022
Publisher: Walter de Gruyter GmbH
Date: 12-2009
DOI: 10.3139/146.110223
Abstract: A commercial purity Al alloy and an Al-0.3Sc (wt.%) alloy, the latter in either the supersaturated or artificially aged condition, were accumulative roll bonded at either 200 or 350°C to high strain to generate sheet materials consisting of 32 or 64 alternating layers of Al and Al(Sc). The microstructure and texture of the processed materials were investigated mainly using electron backscattered diffraction scanning electron microscopy and transmission electron microscopy. The deformation microstructure and texture of these two alloy combinations were strongly influenced by both the initial heat treatment condition of the Al(Sc) alloy whereby large-scale shear bands were generated during rolling when a dispersion of fine Al 3 Sc particles is present in the Al(Sc) layers. The effect of initial microstructure and processing temperature affected the subsequent recrystallization microstructure and texture of the Al/Al(Sc) composite during annealing at 350°C. Here, the Al(Sc) layers remain unrecrystallized in all materials with the Al layers undergoing continuous and discontinuous recrystallization after low and high temperature ARB, respectively. The lack of recrystallization in the Al(Sc) layers generated an alternating recrystallized/recovered microstructure in all materials.
Publisher: Trans Tech Publications, Ltd.
Date: 04-2009
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.618-619.551
Abstract: A multilayered sheet composite of commercial purity Al and Al-0.3%Sc alloys was produced by accumulative roll bonding. The final sheet material consisted of 64 ultra fine grained layers, each of ~7.8mm in thickness. The as-deformed material was annealed at temperatures ranging from 250 to 350°C to study the changes in microstructure and their associated influence on mechanical properties. The as-deformed structures largely comprised of high angle grain boundaries in the Al layers and low angle grain boundaries in the Al(Sc) layers. During annealing, the structures in the Al(Sc) layers remained unaltered, whereas the Al layers recrystallized rapidly to the full layer thickness. The mechanical properties of the Al-Al(Sc) composite were measured and found to be unique in strength and ductility with annealing temperature having a significant influence on these properties.
Publisher: Iron and Steel Institute of Japan
Date: 2017
Publisher: Elsevier BV
Date: 2017
Publisher: Springer Science and Business Media LLC
Date: 17-01-2013
Publisher: Elsevier BV
Date: 04-2022
Publisher: Springer International Publishing
Date: 2017
Publisher: Copernicus GmbH
Date: 03-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-3036
Abstract: & & Nanoscale analyses of zircon have demonstrated that trace elements, including Pb, can be mobilized to discrete sites in radiation damaged zircon. Although several mechanisms for trace element mobility and segregation in zircon have been proposed, most of this work has been conducted on zircon grains with complex geologic histories, making it difficult to directly determine the mechanisms driving trace element mobility and segregation in zircon. To test among the existing hypotheses for mechanisms driving trace element mobility and segregation, we analyzed both untreated and experimentally heated (1450& #176 C for 24h) Archean zircon using atom probe tomography and transmission electron microscopy (TEM). The s le has a simple, well-characterized thermal history, with no significant thermal events since original crystallization. Despite a high calculated radiation dose (& x 10& sup& & /sup& a/g), the untreated zircon does not contain anomalous nanoscale features. In contrast, the experimentally heated zircon contains abundant clusters of Y, Mg, Al, Pb + Yb that range from 5 nm to 25 nm in diameter with toroidal polyhedral morphologies. The & sup& & /sup& Pb/& sup& & /sup& Pb measured from Pb atoms located within these features is consistent with present-day segregation, thus confirming that these nanoscale features were produced by experimental heating in the laboratory. TEM analysis determined that the clusters are dislocation loops, and that cluster morphology is therefore crystallographically controlled. The largest loops are located in {100} and contain high concentrations of Mg and Al.& & & & These experimentally induced, trace-element-enriched clusters are similar in size, morphology, composition, and crystallographic orientation to clusters observed in zircon affected by natural geologic processes (cf. Valley et al., 2015 Peterman et al., 2016). Although the calculated radiation doses for all analyzed grains are high, comparison of the nanoscale features indicates no apparent correlation between the radiation dose and the density or distribution of clusters. We also observe that trace-element-enriched clusters are conspicuously absent from zircon grains that lack younger igneous or metamorphic rims. These findings suggest that the pressure-temperature-time (P-T-t) history and the dT/dt significantly impact both the nanoscale redistribution of trace elements and the density of these features within zircon. Systematic evaluation of the composition and distribution of these features provides a framework for understanding the nanoscale record of metamorphism.& & & & & & & & & References:& & & & Peterman, E.M., Reddy, S.M, Saxey, D.W., Snoeyenbos, D.R., Rickard, W.D.A., Fougerouse, D., and Kylander-Clark, A.R.C. (2016) Nanogeochronology of discordant zircon measured by atom probe microscopy of Pb-enriched dislocation loops. Science Advances, 2, e:1601218.& & & & Valley, J.W., Reinhard, D.A., Cavosie, A.J., Ushikubo, T., Lawrence, D.F., Larson, D.J., Kelly, T.F., Snoeyenbos, DR., and Strickland, A. (2015) Nano-and micro-geochronology in Hadean and Archean zircons by atom-probe tomography and SIMS: New tools for old minerals. American Mineralogist, 100, 1355-1377.& &
Publisher: Association for Materials Protection and Performance (AMPP)
Date: 02-12-2021
DOI: 10.5006/3949
Abstract: Low alloy steels combine relatively low cost with exceptional mechanical properties, making them commonplace in oil and gas equipment. However, their strength and hardness are restricted for sour environments to prevent different forms of hydrogen embrittlement. Materials used in sour services are regulated by the ISO 15156-2 standard, which imposes a maximum hardness of 250 HV (22 HRC) and allows up to 1.0 wt% Ni additions due to hydrogen embrittlement concerns. Low alloy steels that exceed the ISO 15156-2 limit have to be qualified for service, lowering their commercial appeal. As a result, high-performing, usually high-nickel, low alloy steels used successfully in other industries are rarely considered for sour service. In this work, the hydrogen stress cracking resistance of the high-nickel (3.41 wt%), quenched and tempered, nuclear-grade ASTM A508 Gr.4N low alloy steel was investigated using slow strain rate testing as a function of applied cathodic potential. Results showed that the yield strength and ultimate tensile strength were unaffected by hydrogen, even at a high negative potential of −2.00 VAg/AgCl. Hydrogen embrittlement effects were observed once the material started necking, manifested by a loss in ductility with increasing applied cathodic potentials. Indeed, A508 Gr.4N was less affected by hydrogen at high cathodic potentials than a low-strength (yield strength = 340 MPa) ferritic-pearlitic low alloy steel of similar nickel content. Additionally, hydrogen diffusivity was measured using the hydrogen permeation test. The calculated hydrogen diffusion coefficient of the ASTM A508 Gr.4N was two orders of magnitude smaller when compared to that of ferritic-pearlitic steels. Hydrogen embrittlement and diffusion results were linked to the microstructure features. The microstructure consisted of a bainitic/martensitic matrix with the presence of Cr23C6 carbides as well as Mo- and V-rich precipitates, which might have played a role in retarding hydrogen diffusion, kept responsible for the improved HE resistance.
Publisher: Springer International Publishing
Date: 2017
Publisher: IOP Publishing
Date: 07-08-2015
Publisher: Elsevier BV
Date: 04-2012
Publisher: Elsevier BV
Date: 09-2007
Publisher: Iron and Steel Institute of Japan
Date: 2014
Publisher: Springer Science and Business Media LLC
Date: 28-02-2020
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 09-2006
Publisher: Mineralogical Society of America
Date: 04-2020
DOI: 10.2138/AM-2020-7236
Abstract: Cristobalite is a low-pressure, high-temperature SiO2 polymorph that occurs as a metastable phase in many geologic settings, including as crystals deposited from vapor within the pores of volcanic rocks. Such vapor-phase cristobalite (VPC) has been inferred to result from silica redistribution by acidic volcanic gases but a precise mechanism for its formation has not been established. We address this by investigating the composition and structure of VPC deposited on plagioclase substrates within a rhyolite lava flow, at the micrometer to nanometer scale. The VPC contains impurities of the form [AlO4/Na+]0—coupled substitution of Al3+ charge-balanced by interstitial Na+—which are typical of cristobalite. However, new electron probe microanalysis (EPMA) element maps show in idual crystals to have impurity concentrations that systematically decline from crystal cores-to-rims, and atom probe tomography reveals localized segregation of impurities to dislocations. Impurity concentrations are inversely correlated with degrees of crystallinity [observed by electron backscatter diffraction (EBSD), hyperspectral cathodoluminescence, laser Raman, and transmission electron microscopy (TEM)], such that crystal cores are poorly crystalline and rims are highly ordered tetragonal α-cristobalite. The VPC-plagioclase interfaces show evidence that dissolution-reprecipitation reactions between acidic gases and plagioclase crystals yield precursory amorphous SiO2 coatings that are suitable substrates for initial deposition of impure cristobalite. Successive layers of cubic β-cristobalite are deposited with impurity concentrations that decline as Al-bearing gases rapidly become unstable in the vapor cooling within pores. Final cooling to ambient temperature causes a displacive transformation from β→α cristobalite, but with locally expanded unit cells where impurities are abundant. We interpret this mechanism of VPC deposition to be a natural proxy for dopant-modulated Chemical Vapor Deposition, where halogen-rich acidic gases uptake silica, react with plagioclase surfaces to form suitable substrates and then deposit SiO2 as impure cristobalite. Our results have implications for volcanic hazards, as it has been established that the toxicity of crystalline silica is positively correlated with its purity. Furthermore, we note that VPC commonly goes unreported, but has been observed in silicic lavas of virtually all compositions and eruptive settings. We therefore suggest that despite being metastable at Earth's surface, cristobalite may be the most widely occurring SiO2 polymorph in extrusive volcanic rocks and a useful indicator of gas-solid reaction having occurred in cooling magma bodies.
Publisher: Springer Science and Business Media LLC
Date: 16-11-2015
Publisher: Elsevier BV
Date: 2022
Publisher: Trans Tech Publications, Ltd.
Date: 12-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.702-703.101
Abstract: The crystallographic alignment of microbands in a Goss oriented single crystal was investigated by two and three dimensional electron back scatter diffraction. The microband boundaries were found to be curved instead of being perfectly flat interfaces, and the overall alignment closely matched a potential slip plane. The bumps and curved were created during subsequent deformation and, thus, deviates the microband boundaries from crystallographic nature.
Publisher: Springer Science and Business Media LLC
Date: 14-07-2015
Publisher: Elsevier BV
Date: 02-2013
Publisher: The Electrochemical Society
Date: 03-2021
Abstract: Precipitation hardened nickel-based Alloy 725 (UNS N07725) has been proven susceptible to hydrogen embrittlement in oil and gas production. Moreover, current standards cannot differentiate unequivocally between acceptable and affected microstructures, making the development of an appropriate quality control test a priority for the oil and gas industry. Recently, Alloy 725 failures were associated with the precipitation of nanoscale Cr- and Mo-rich phases at grain boundaries (GBs). Since these intergranular precipitates could lead to Cr- and Mo-depletion along the decorated GBs (i.e., sensitization), the double-loop electrochemical potentiokinetic reactivation (DL-EPR) test was explored as an alternative approach to detect affected microstructures. Herein, the DL-EPR technique was optimized for Alloy 725 by testing three types of s les with different degrees of sensitization, including a full GB-decorated microstructure that was shown prone to hydrogen embrittlement in oil and gas service. The optimized DL-EPR test conditions were 2 M HCl + 1 M H 2 SO 4 + 10 −4 M KSCN aqueous solution at 30 °C with a 1.667 mV s −1 scan rate and a vertex potential of E corr + 700 mV. Results were reproducible and consistent with the degree of GB decoration determined using metallographic methods. The test procedure developed herein could lead to the standardization of the DL-EPR method for Alloy 725.
Publisher: Trans Tech Publications, Ltd.
Date: 04-2009
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.618-619.575
Abstract: Accumulative Roll Bonding (ARB) is a severe plastic deformation technique for producing ultra-fine grain structures in sheet metal. In this investigation, the through-thickness shear strain distribution during single pass rolling of roll-bonded aluminium sheets was monitored via the deflection of an embedded scratch on the through-thickness, pre-polished surface of the material. It was found that, near the sheet surface and at its mid-thickness, rolling generated severe and moderate shearing, respectively. Such shearing was found to have a strong influence on the microstructure and crystallographic texture of the material, which was eliminated during subsequent rolling cycles. Compared to the core of a given rolled layer, both the microstructure and texture at the interface of the layers was inhomogeneous.
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 06-2016
Publisher: Iron and Steel Institute of Japan
Date: 2006
Publisher: AIP Publishing
Date: 2020
DOI: 10.1063/12.0000820
Publisher: Elsevier BV
Date: 05-2017
Publisher: Elsevier BV
Date: 03-2016
Publisher: Springer International Publishing
Date: 2016
Publisher: Author(s)
Date: 2015
DOI: 10.1063/1.4971641
Publisher: Wiley
Date: 08-05-2015
DOI: 10.1111/JACE.13620
Abstract: Fracture of silicon wafers is responsible for lower than desirable manufacturing yields in the photovoltaic industry. This study investigates the fracture response of polycrystalline silicon wafers under sliding contacts at different length scales, by means of macro and microscratch tests which simulate cutting processes. The dominant fracture modes were found to be partial cone cracking (macro) and radial cracking (micro). Statistical analysis of the critical loads for crack initiation showed that polycrystalline wafers are weaker than their single‐crystal counterparts, that is, they crack at lower applied loads under comparable conditions. Moreover, the Weibull modulus of polycrystalline silicon was found to be the average of the relevant single‐crystal directions. Subsequent microscopic observations and flexure tests reveal that the lower resistance of polycrystalline silicon to scratch fracture is due mainly to the presence of relatively large polishing defects, and not to the weakness of its grain boundaries. Alternatives are proposed to minimize damage during ingot cutting, with a view to minimizing wafer breakages during wafer handling and machining.
No related grants have been discovered for Md Zakaria Quadir.