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Turski M.,Open University Milton Keynes | Paradowska A.,Australian Nuclear Science and Technology Organisation | Paradowska A.,Rutherford Appleton Laboratory | Zhang S.-Y.,Rutherford Appleton Laboratory | And 6 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2012

A significant level of cold cracking has been observed within direct chill (DC) cast, high-strength magnesium alloy Elektron WE43. These cracks have been attributed to the formation of significant residual stresses during casting. A finite-element modeling (FEM) code, which is called ALSIM, has been used to predict the residual stress within the DC-cast slab. Verification of the predicted residual stress field within an 870 9 315-mm sized slab has been carried out using neutron diffraction measurements. Given that measurements in such large-scale components using diffraction measurements are particularly challenging and expensive, the efficient use of neutron diffraction measurements is emphasized. This has included the use of sectioning, allowing the residual stress within the slab to be mapped in detail. © 2012 The Minerals, Metals & Materials Society and ASM International.


Turski M.,Magnesium Elektron Ltd. | Grandfield J.F.,Grandfield Technology Pty. Ltd. | Wilks T.,Magnesium Elektron Ltd. | Davis B.,Magnesium Elektron North America Inc. | And 2 more authors.
Magnesium Technology | Year: 2010

During direct chill (DC) casting, significant stresses can develop within the material leading to cracking within the cast slab. The situation is made worse for higher strength magnesium alloys, such as Elektron™ WE43, which exhibits high strength at elevated temperatures. Consequently, the temperature and stress field must be well understood during the casting process to avoid failure during casting. ALSIM is a fully coupled thermomechanical finite element modeling code capable of simulating the DC casting process. ALSIM was used to simulate vertical DC casting of Elektron™ WE43 slab. Validation of the model was carried out by the insertion of thermocouples during casting and post-mortem sectioning of cast slabs containing cracks. Agreement has been found between the modeling predictions and thermocouple measurements and post-mortem examination of cast material. The use of this validated model has allowed optimized casting parameters to be developed to produce crack-free Elektron™ WE43 slab.


Agnew S.,University of Virginia | Whittington W.,Mississippi State University | Oppedal A.,Mississippi State University | El Kadiri H.,Mississippi State University | And 5 more authors.
JOM | Year: 2014

The dynamic behavior of Mg alloys is an area of interest for applications such as crash-sensitive automotive components and armor. The rare-earth element-containing alloy WE43B-T5 has performed well in ballistic testing, so the quasi-static (~10-3 1/s) and dynamic (~600-5000 1/s) mechanical behaviors of two Mg alloys, rolled WE43B-T5 and extruded AM30-F, were investigated using servohydraulic and Kolsky bar testing in uniaxial tension and compression. The yield stress was surprisingly isotropic for WE43B-T5 relative to conventional Mg alloys (including extruded AM30-F). The WE43B plate was textured; however, it was not the typical basal texture of hot-rolled Mg-Al alloys. The effect of strain rate on the yield strength of WE43B-T5 is small and the strain-hardening behavior is only mildly rate sensitive (m = 0.008). The combination of high strength (~300 MPa), moderate ductility (0.07-0.20), and low density yield a material with good specific energy absorption capacity. © 2014 The Minerals, Metals & Materials Society.


Panigrahi S.K.,Missouri University of Science and Technology | Yuan W.,Missouri University of Science and Technology | Mishra R.S.,Missouri University of Science and Technology | DeLorme R.,Magnesium Elektron North America Inc. | And 3 more authors.
Materials Science and Engineering A | Year: 2011

The combined effect of forging and aging on microstructural evolution and mechanical properties of a Mg-Y-RE alloy was studied in the present work by employing hardness measurements, tensile tests, optical microscopy (OM), scanning electron microscopy (SEM) and electron back scattered diffraction (EBSD) analysis. The -F temper treated bulk Mg-Y-RE alloy samples were subjected to forging for microstructural refinement and subsequent aging to maximize the strength-ductility combination. The forged samples combined with peak aging treatment (60 h at 180 °C) exhibited an excellent combination of high strength (388 MPa) and high ductility (23%). The combined effect of grain refinement, work hardening, precipitation strengthening and recovery is responsible for the simultaneous improvement of both strength and ductility. A comparative study of age hardening response of forged samples and as received samples showed higher hardenability in forged samples. © 2011 Elsevier B.V.


Davis B.,Magnesium Elektron North America Inc.
Magnesium Technology | Year: 2015

The commercial aircraft market is forecast to steadily grow over the next two decades. Part of this growth is driven by the desire of airlines to replace older models in their fleet with newer, more fuel efficient designs, to realize lower operating costs and to address the rising cost of aviation fuel. As such the aircraft OEMs are beginning to set more and more demanding mass targets on their new platforms. The cabin interior, including tnrnishings and operational items, account for 19% of the overall aircraft weight. This establishes it as a significant area for weight savings. Modem magnesium alloys can offer up to 30% mass reduction when directly replacing aluminum components, which makes them very attractive to designers and engineers. However, until recently, there have been restrictions on the use of magnesium in aircraft interiors that have been enforced through the SAE and the FAA. Copyright © 2015 by The Minerals, Metals & Materials Society.


Brady M.P.,Oak Ridge National Laboratory | Rother G.,Oak Ridge National Laboratory | Anovitz L.M.,Oak Ridge National Laboratory | Littrell K.C.,Oak Ridge National Laboratory | And 7 more authors.
Journal of the Electrochemical Society | Year: 2015

Small angle neutron scattering (SANS) and scanning transmission electron microscopy (STEM) were used to study film formation by magnesium alloys AZ31B (Mg-3Al-1Zn base) and ZE10A (Elektron 717, E717: Mg-1Zn + Nd, Zr) in H2O and D2O with and without 1 or 5 wt% NaCl. No SANS scattering changes were observed after 24 h D2O or H2O exposures compared with as-received (unreacted) alloy, consistent with relatively dense MgO-base film formation. However, exposure to 5 wt% NaCl resulted in accelerated corrosion, with resultant SANS scattering changes detected. The SANS data indicated both particle and rough surface (internal and external) scattering, but with no preferential size features. The films formed in 5 wt% NaCl consisted of a thin, inner MgO-base layer, and a nano-porous and filamentous Mg(OH)2 outer region tens of microns thick. Chlorine was detected extending to the inner MgO-base film region, with segregation of select alloying elements also observed in the inner MgO, but not the outer Mg(OH)2. Modeling of the SANS data suggested that the outer Mg(OH)2 films had very high surface areas, consistent with loss of film protectiveness. Implications for the NaCl corrosion mechanism, and the potential utility of SANS for Mg corrosion, are discussed. © The Author(s) 2015. Published by ECS.


Brady M.P.,Oak Ridge National Laboratory | Fayek M.,University of Manitoba | Meyer H.M.,Oak Ridge National Laboratory | Leonard D.N.,Oak Ridge National Laboratory | And 8 more authors.
Scripta Materialia | Year: 2015

The oxidation of pure Mg, Mg-3Al-1Zn (AZ31B), and Mg-1Zn-0.25Zr-<0.5Nd (ZE10A) was studied at 85 °C in humid air using sequential exposures with H2 18O and D2 16O for water vapor. Incorporation of 18O in the hydroxide/oxide films indicated that oxygen from water vapor participated in the reaction. Penetration of hydrogen into the underlying metal was observed, particularly for the Zr- and Nd-containing ZE10A. Isotopic tracer profiles suggested a complex mixed inward/outward film growth mechanism. © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Brady M.P.,Oak Ridge National Laboratory | Fayek M.,University of Manitoba | Elsentriecy H.H.,Oak Ridge National Laboratory | Elsentriecy H.H.,Central Metallurgical Research and Development Institute | And 5 more authors.
Journal of the Electrochemical Society | Year: 2014

An isotopic tracer study of the film growth mechanism for pure magnesium, AZ31B, and ZE10A (Elektron 717, E717) magnesium alloys in water at room temperature was performed. A series of individual and sequential exposures were conducted in both H2 18O and D2 16O, with isotopic tracer profiles obtained using secondary ion mass spectrometry (SIMS). The water-formed films consisted primarily of partially hydrated MgO. The SIMS sputter depth profiles indicate that H and D penetrated throughout the film and into the underlying metal, particularly for the Zr- and Nd-containing E717 alloy. Film growth for the UHP Mg involved aspects of both metal outward diffusion and oxygen/hydrogen inward diffusion. In contrast, the film on the Al-containing AZ31B alloy grew primarily by inward oxygen and inward hydrogen diffusion. The 18O and D profiles for the film formed on E717 were the most complex, with the 18O data most consistent with inward lattice oxygen diffusion, but the D data suggests inward, short-circuit diffusion through the film. It is speculated that preferential inward short circuit hydrogen transport may have been aided by the presence of nano Zn 2Zr3 particles throughout the E717 film. Such hydrogen penetration may have implications from both a corrosion resistance and hydrogen storage perspective. © The Author(s) 2014. Published by ECS. All rights reserved. Published by ECS.


Unocic K.A.,Oak Ridge National Laboratory | Elsentriecy H.H.,Central Metallurgical Research and Development Institute | Brady M.P.,Oak Ridge National Laboratory | Meyer H.M.,Oak Ridge National Laboratory | And 4 more authors.
Journal of the Electrochemical Society | Year: 2014

The films formed on ultrahigh purity Mg, Elektron 717 (ZE10A), and AZ31B in water at room temperature were characterized by TEM, XPS, and SIMS. The films consisted primarily of MgO, with surface regions also containing Mg(OH) 2 and MgCO3. SIMS suggested H throughout the films and into the underlying metal. Segregation of Zn to the metal/film interface and Al in the film was observed for AZ31B. Similar Zn film segregation was also detected for Elektron 717, along with Nd at the alloy/film interface and nano-size Zn2Zr3 precipitates throughout the film. Implications of these findings on film growth are discussed. © 2014 The Electrochemical Society.


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Magnesium Elektron North America Inc. | Date: 2016-03-21

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