Special Issue "Metals Challenged by Neutron and Synchrotron Radiation"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (30 November 2015)

Special Issue Editor

Guest Editor
Prof. Dr. Klaus-Dieter Liss

Guangdong Technion - Israel Institute of Technology (GTIIT), 241 Daxue Lu, Jinping Qu, Shantou, Guangdong Province, China
Website | E-Mail
Phone: +86 136 7612 7052
Interests: in-situ, time-resolved scattering; structural and functional materials; metals; semiconductors; thermo-mechanical processing; phase transformations; ferroics; kinetics and dynamics; extreme conditions; texture analysis; plasticity; materials development; metallic glass; light metals; TiAl intermetallics; steels; diffraction optics; interferometry; ultra-short time scales; synchrotrons; neutrons; free-electron lasers

Special Issue Information

Dear Colleagues,

In the past decade, neutron and synchrotron radiation techniques have come to the forefront as an excellent set of tools for the investigation of materials structure and properties. This holds true, especially for metals. The goal of this Special Issue is to compile a broad range of state-of-the-art contributions in this field into a single collection. Gathering reviews of diffraction and scattering methods, data reconstruction and combined modeling, as well as applications on particular metallic systems, such as titanium aluminides, magnesium, steels, nuclear metals, etc., is of interest. This Special Issue also seeks detailed and accurate case-studies on individual systems. Research fields of interest will range from engineering, through materials design to fundamental materials science. I wish to suggest non-exclusively, strain scanning, texture analysis, phase transformation, precipitation, microstructure reconstruction, crystal defects, atomic structures (both crystalline and amorphous), order and disorder, kinetics, time resolved microstructure evolution, local structure correlations, phonons, deformation and transformation mechanisms, response to extreme conditions, local and integrated studies, in bulk and at interfaces. Techniques will be mainly based on neutrons and synchrotron X-rays, and may be complemented by other quantum beams, such as electron diffraction, muon spectroscopy, and microscopic techniques. Advanced techniques include high-energy X-ray diffraction, microbeam techniques, X-ray microscope, materials oscilloscope, coherent beam scattering, three-dimensional X-ray diffraction, texture analysis, in-situ studies, time resolved, pump-probe techniques, neutron and X-ray spectroscopy, quantitative phase analysis, peak profile analysis, to mention but a few.

Prof. Dr. Klaus-Dieter Liss
Guest Editor

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Manuscript Submission Information

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Keywords

  • diffraction; imaging; spectroscopy
  • poly-crystalline; single-crystalline; amorphous
  • structural changes; kinetics; time-resolved
  • phase transformations; microstructures; plasticity; mechanisms
  • strain; stress; texture
  • reciprocal space; real space; coherent beams
  • phonons; vibrations; ultrashort times
  • high energy synchrotron X-rays; neutron reactor; spallation source; free-electron laser
  • light metals; steels; intermetallics; special metals
  • extreme conditions; high temperature; uni-axial load; impact; high-pressure

Published Papers (22 papers)

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Editorial

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Open AccessEditorial Metals Challenged by Neutron and Synchrotron Radiation
Metals 2017, 7(7), 266; doi:10.3390/met7070266
Received: 28 June 2017 / Accepted: 29 June 2017 / Published: 11 July 2017
Cited by 1 | PDF Full-text (186 KB) | HTML Full-text | XML Full-text
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Research

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Open AccessArticle Hydrostatic Compression Behavior and High-Pressure Stabilized β-Phase in γ-Based Titanium Aluminide Intermetallics
Metals 2016, 6(7), 165; doi:10.3390/met6070165
Received: 15 April 2016 / Revised: 30 May 2016 / Accepted: 13 June 2016 / Published: 15 July 2016
Cited by 6 | PDF Full-text (6085 KB) | HTML Full-text | XML Full-text | Correction
Abstract
Titanium aluminides find application in modern light-weight, high-temperature turbines, such as aircraft engines, but suffer from poor plasticity during manufacturing and processing. Huge forging presses enable materials processing in the 10-GPa range, and hence, it is necessary to investigate the phase diagrams of
[...] Read more.
Titanium aluminides find application in modern light-weight, high-temperature turbines, such as aircraft engines, but suffer from poor plasticity during manufacturing and processing. Huge forging presses enable materials processing in the 10-GPa range, and hence, it is necessary to investigate the phase diagrams of candidate materials under these extreme conditions. Here, we report on an in situ synchrotron X-ray diffraction study in a large-volume press of a modern (α2 + γ) two-phase material, Ti-45Al-7.5Nb-0.25C, under pressures up to 9.6 GPa and temperatures up to 1686 K. At room temperature, the volume response to pressure is accommodated by the transformation γ → α2, rather than volumetric strain, expressed by the apparently high bulk moduli of both constituent phases. Crystallographic aspects, specifically lattice strain and atomic order, are discussed in detail. It is interesting to note that this transformation takes place despite an increase in atomic volume, which is due to the high ordering energy of γ. Upon heating under high pressure, both the eutectoid and γ-solvus transition temperatures are elevated, and a third, cubic β-phase is stabilized above 1350 K. Earlier research has shown that this β-phase is very ductile during plastic deformation, essential in near-conventional forging processes. Here, we were able to identify an ideal processing window for near-conventional forging, while the presence of the detrimental β-phase is not present under operating conditions. Novel processing routes can be defined from these findings. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessFeature PaperArticle Hydrogen Absorption in Metal Thin Films and Heterostructures Investigated in Situ with Neutron and X-ray Scattering
Metals 2016, 6(6), 125; doi:10.3390/met6060125
Received: 16 April 2016 / Revised: 13 May 2016 / Accepted: 17 May 2016 / Published: 24 May 2016
Cited by 3 | PDF Full-text (3866 KB) | HTML Full-text | XML Full-text
Abstract
Due to hydrogen possessing a relatively large neutron scattering length, hydrogen absorption and desorption behaviors in metal thin films can straightforwardly be investigated by neutron reflectometry. However, to further elucidate the chemical structure of the hydrogen absorbing materials, complementary techniques such as high
[...] Read more.
Due to hydrogen possessing a relatively large neutron scattering length, hydrogen absorption and desorption behaviors in metal thin films can straightforwardly be investigated by neutron reflectometry. However, to further elucidate the chemical structure of the hydrogen absorbing materials, complementary techniques such as high resolution X-ray reflectometry and diffraction remain important too. Examples of work on such systems include Nb- and Pd-based multilayers, where Nb and Pd both have strong affinity to hydrogen. W/Nb and Fe/Nb multilayers were measured in situ with unpolarized and polarized neutron reflectometry under hydrogen gas charging conditions. The gas-pressure/hydrogen-concentration dependence, the hydrogen-induced macroscopic film swelling as well as the increase in crystal lattice plane distances of the films were determined. Ferromagnetic-Co/Pd multilayers were studied with polarized neutron reflectometry and in situ ferromagnetic resonance measurements to understand the effect of hydrogen absorption on the magnetic properties of the system. This electronic effect enables a novel approach for hydrogen sensing using a magnetic readout scheme. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessFeature PaperArticle Monte Carlo Modelling of Single-Crystal Diffuse Scattering from Intermetallics
Metals 2016, 6(2), 33; doi:10.3390/met6020033
Received: 2 December 2015 / Accepted: 27 January 2016 / Published: 4 February 2016
Cited by 1 | PDF Full-text (2172 KB) | HTML Full-text | XML Full-text
Abstract
Single-crystal diffuse scattering (SCDS) reveals detailed structural insights into materials. In particular, it is sensitive to two-body correlations, whereas traditional Bragg peak-based methods are sensitive to single-body correlations. This means that diffuse scattering is sensitive to ordering that persists for just a few
[...] Read more.
Single-crystal diffuse scattering (SCDS) reveals detailed structural insights into materials. In particular, it is sensitive to two-body correlations, whereas traditional Bragg peak-based methods are sensitive to single-body correlations. This means that diffuse scattering is sensitive to ordering that persists for just a few unit cells: nanoscale order, sometimes referred to as “local structure”, which is often crucial for understanding a material and its function. Metals and alloys were early candidates for SCDS studies because of the availability of large single crystals. While great progress has been made in areas like ab initio modelling and molecular dynamics, a place remains for Monte Carlo modelling of model crystals because of its ability to model very large systems; important when correlations are relatively long (though still finite) in range. This paper briefly outlines, and gives examples of, some Monte Carlo methods appropriate for the modelling of SCDS from metallic compounds, and considers data collection as well as analysis. Even if the interest in the material is driven primarily by magnetism or transport behaviour, an understanding of the local structure can underpin such studies and give an indication of nanoscale inhomogeneity. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessFeature PaperArticle Probing Interfaces in Metals Using Neutron Reflectometry
Metals 2016, 6(1), 20; doi:10.3390/met6010020
Received: 25 November 2015 / Revised: 7 December 2015 / Accepted: 21 December 2015 / Published: 20 January 2016
Cited by 2 | PDF Full-text (2257 KB) | HTML Full-text | XML Full-text
Abstract
Solid-state interfaces play a major role in a variety of material properties. They are especially important in determining the behavior of nano-structured materials, such as metallic multilayers. However, interface structure and properties remain poorly understood, in part because the experimental toolbox for characterizing
[...] Read more.
Solid-state interfaces play a major role in a variety of material properties. They are especially important in determining the behavior of nano-structured materials, such as metallic multilayers. However, interface structure and properties remain poorly understood, in part because the experimental toolbox for characterizing them is limited. Neutron reflectometry (NR) offers unique opportunities for studying interfaces in metals due to the high penetration depth of neutrons and the non-monotonic dependence of their scattering cross-sections on atomic numbers. We review the basic physics of NR and outline the advantages that this method offers for investigating interface behavior in metals, especially under extreme environments. We then present several example NR studies to illustrate these advantages and discuss avenues for expanding the use of NR within the metals community. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessArticle Study on Sintering Mechanism of Stainless Steel Fiber Felts by X-ray Computed Tomography
Metals 2016, 6(1), 18; doi:10.3390/met6010018
Received: 1 October 2015 / Revised: 31 December 2015 / Accepted: 4 January 2016 / Published: 13 January 2016
Cited by 2 | PDF Full-text (1194 KB) | HTML Full-text | XML Full-text
Abstract
The microstructure evolution of Fe-17 wt. % Cr-12 wt. % Ni-2 wt. % Mo stainless steel fiber felts during the fast sintering process was investigated by the synchrotron radiation X-ray computed tomography technique. The equation of dynamics of stable inter-fiber neck growth was
[...] Read more.
The microstructure evolution of Fe-17 wt. % Cr-12 wt. % Ni-2 wt. % Mo stainless steel fiber felts during the fast sintering process was investigated by the synchrotron radiation X-ray computed tomography technique. The equation of dynamics of stable inter-fiber neck growth was established for the first time based on the geometry model of sintering joints of two fibers and Kucsynski’s two-sphere model. The specific evolutions of different kinds of sintering joints were observed in the three-dimensional images. The sintering mechanisms during sintering were proposed as plastic flow and grain boundary diffusion, the former leading to a quick growth of sintering joints. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessArticle Deformation in Metallic Glasses Studied by Synchrotron X-Ray Diffraction
Metals 2016, 6(1), 22; doi:10.3390/met6010022
Received: 10 December 2015 / Revised: 6 January 2016 / Accepted: 7 January 2016 / Published: 11 January 2016
Cited by 3 | PDF Full-text (2228 KB) | HTML Full-text | XML Full-text
Abstract
High mechanical strength is one of the superior properties of metallic glasses which render them promising as a structural material. However, understanding the process of mechanical deformation in strongly disordered matter, such as metallic glass, is exceedingly difficult because even an effort to
[...] Read more.
High mechanical strength is one of the superior properties of metallic glasses which render them promising as a structural material. However, understanding the process of mechanical deformation in strongly disordered matter, such as metallic glass, is exceedingly difficult because even an effort to describe the structure qualitatively is hampered by the absence of crystalline periodicity. In spite of such challenges, we demonstrate that high-energy synchrotron X-ray diffraction measurement under stress, using a two-dimensional detector coupled with the anisotropic pair-density function (PDF) analysis, has greatly facilitated the effort of unraveling complex atomic rearrangements involved in the elastic, anelastic, and plastic deformation of metallic glasses. Even though PDF only provides information on the correlation between two atoms and not on many-body correlations, which are often necessary in elucidating various properties, by using stress as means of exciting the system we can garner rich information on the nature of the atomic structure and local atomic rearrangements during deformation in glasses. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessArticle Monitoring of Bainite Transformation Using in Situ Neutron Scattering
Metals 2016, 6(1), 16; doi:10.3390/met6010016
Received: 22 November 2015 / Revised: 22 December 2015 / Accepted: 6 January 2016 / Published: 9 January 2016
Cited by 3 | PDF Full-text (1817 KB) | HTML Full-text | XML Full-text
Abstract
Bainite transformation behavior was monitored using simultaneous measurements of dilatometry and small angle neutron scattering (SANS). The volume fraction of bainitic ferrite was estimated from the SANS intensity, showing good agreement with the results of the dilatometry measurements. We propose a more advanced
[...] Read more.
Bainite transformation behavior was monitored using simultaneous measurements of dilatometry and small angle neutron scattering (SANS). The volume fraction of bainitic ferrite was estimated from the SANS intensity, showing good agreement with the results of the dilatometry measurements. We propose a more advanced monitoring technique combining dilatometry, SANS and neutron diffraction. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessArticle Investigation of Elastic Deformation Mechanism in As-Cast and Annealed Eutectic and Hypoeutectic Zr–Cu–Al Metallic Glasses by Multiscale Strain Analysis
Metals 2016, 6(1), 12; doi:10.3390/met6010012
Received: 24 November 2015 / Revised: 23 December 2015 / Accepted: 30 December 2015 / Published: 5 January 2016
Cited by 1 | PDF Full-text (2782 KB) | HTML Full-text | XML Full-text
Abstract
Elastic deformation behaviors of as-cast and annealed eutectic and hypoeutectic Zr–Cu–Al bulk metallic glasses (BMG) were investigated on a basis of different strain-scales, determined by X-ray scattering and the strain gauge. The microscopic strains determined by Direct-space method and Reciprocal-space method were compared
[...] Read more.
Elastic deformation behaviors of as-cast and annealed eutectic and hypoeutectic Zr–Cu–Al bulk metallic glasses (BMG) were investigated on a basis of different strain-scales, determined by X-ray scattering and the strain gauge. The microscopic strains determined by Direct-space method and Reciprocal-space method were compared with the macroscopic strain measured by the strain gauge, and the difference in the deformation mechanism between eutectic and hypoeutectic Zr–Cu–Al BMGs was investigated by their correlation. The eutectic Zr50Cu40Al10 BMG obtains more homogeneous microstructure by free-volume annihilation after annealing, improving a resistance to deformation but degrading ductility because of a decrease in the volume fraction of weakly-bonded regions with relatively high mobility. On the other hand, the as-cast hypoeutectic Zr60Cu30Al10 BMG originally has homogeneous microstructure but loses its structural and elastic homogeneities because of nanocluster formation after annealing. Such structural changes by annealing might develop unique mechanical properties showing no degradations of ductility and toughness for the structural-relaxed hypoeutectic Zr60Cu30Al10 BMGs. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessArticle In situ Investigation of Titanium Powder Microwave Sintering by Synchrotron Radiation Computed Tomography
Metals 2016, 6(1), 9; doi:10.3390/met6010009
Received: 3 October 2015 / Revised: 22 December 2015 / Accepted: 23 December 2015 / Published: 4 January 2016
Cited by 3 | PDF Full-text (3770 KB) | HTML Full-text | XML Full-text
Abstract
In this study, synchrotron radiation computed tomography was applied to investigate the mechanisms of titanium powder microwave sintering in situ. On the basis of reconstructed images, we observed that the sintering described in this study differs from conventional sintering in terms of
[...] Read more.
In this study, synchrotron radiation computed tomography was applied to investigate the mechanisms of titanium powder microwave sintering in situ. On the basis of reconstructed images, we observed that the sintering described in this study differs from conventional sintering in terms of particle smoothing, rounding, and short-term growth. Contacted particles were also isolated. The kinetic curves of sintering neck growth and particle surface area were obtained and compared with those of other microwave-sintered metals to examine the interaction mechanisms between mass and microwave fields. Results show that sintering neck growth accelerated from the intermediate period; however, this finding is inconsistent with that of aluminum powder microwave sintering described in previous work. The free surface areas of the particles were also quantitatively analyzed. In addition to the eddy current loss in metal particles, other heating mechanisms, including dielectric loss, interfacial polarization effect, and local plasma-activated sintering, contributed to sintering neck growth. Thermal and non-thermal effects possibly accelerated the sintering neck growth of titanium. This study provides a useful reference of further research on interaction mechanisms between mass and microwave fields during microwave sintering. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessArticle Forge-Hardened TiZr Null-Matrix Alloy for Neutron Scattering under Extreme Conditions
Metals 2015, 5(4), 2340-2350; doi:10.3390/met5042340
Received: 8 October 2015 / Revised: 2 December 2015 / Accepted: 7 December 2015 / Published: 9 December 2015
Cited by 4 | PDF Full-text (902 KB) | HTML Full-text | XML Full-text
Abstract
For neutron scattering research that is performed under extreme conditions, such as high static pressures, high-strength metals that are transparent to the neutron beam are required. The diffraction of the neutron beam by the metal, which follows Bragg’s law, can be completely removed
[...] Read more.
For neutron scattering research that is performed under extreme conditions, such as high static pressures, high-strength metals that are transparent to the neutron beam are required. The diffraction of the neutron beam by the metal, which follows Bragg’s law, can be completely removed by alloying two metallic elements that have coherent scattering lengths with opposite signs. An alloy of Ti and Zr, which is known as a TiZr null-matrix alloy, is an ideal combination for such purposes. In this study, we increased the hardness of a TiZr null-matrix alloy via extensive mechanical deformation at high temperatures. We successfully used the resulting product in a high-pressure cell designed for high-static-pressure neutron scattering. This hardened TiZr null-matrix alloy may play a complementary role to normal TiZr alloy in future neutron scattering research under extreme conditions. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessFeature PaperArticle In Situ High-Energy X-ray Diffraction during Hot-Forming of a Multiphase TiAl Alloy
Metals 2015, 5(4), 2252-2265; doi:10.3390/met5042252
Received: 28 September 2015 / Revised: 19 November 2015 / Accepted: 23 November 2015 / Published: 30 November 2015
Cited by 5 | PDF Full-text (1160 KB) | HTML Full-text | XML Full-text
Abstract
Intermetallic γ-TiAl based alloys exhibit excellent high-temperature strength combined with low density. This makes them ideal candidates for replacing the twice as dense Ni base super-alloys, currently used in the medium temperature range (~700 °C) of industrial and aviation gas turbines. An important
[...] Read more.
Intermetallic γ-TiAl based alloys exhibit excellent high-temperature strength combined with low density. This makes them ideal candidates for replacing the twice as dense Ni base super-alloys, currently used in the medium temperature range (~700 °C) of industrial and aviation gas turbines. An important step towards the serial production of TiAl parts is the development of suitable hot-forming processes. Thermo-mechanical treatments often result in mechanical anisotropy due to the formation of crystallographic textures. However, with conventional texture analysis techniques, their formation can only be studied after processing. In this study, in situ high-energy X-ray diffraction measurements with synchrotron radiation were performed during hot-forming. Thus, it was possible to record the evolution of the phase constitution as well as the formation of crystallographic texture of different phases directly during processing. Several process temperatures (1100 °C to 1300 °C) and deformation rates were investigated. Based on these experiments, a process window can be recommended which results in the formation of an optimal reduced texture. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessArticle Dynamic Strain Evolution around a Crack Tip under Steady- and Overloaded-Fatigue Conditions
Metals 2015, 5(4), 2109-2118; doi:10.3390/met5042109
Received: 2 September 2015 / Revised: 26 October 2015 / Accepted: 4 November 2015 / Published: 12 November 2015
Cited by 4 | PDF Full-text (933 KB) | HTML Full-text | XML Full-text
Abstract
We investigated the evolution of the strain fields around a fatigued crack tip between the steady- and overloaded-fatigue conditions using a nondestructive neutron diffraction technique. The two fatigued compact-tension specimens, with a different fatigue history but an identical applied stress intensity factor range,
[...] Read more.
We investigated the evolution of the strain fields around a fatigued crack tip between the steady- and overloaded-fatigue conditions using a nondestructive neutron diffraction technique. The two fatigued compact-tension specimens, with a different fatigue history but an identical applied stress intensity factor range, were used for the direct comparison of the crack tip stress/strain distributions during in situ loading. While strains behind the crack tip in the steady-fatigued specimen are irrelevant to increasing applied load, the strains behind the crack tip in the overloaded-fatigued specimen evolve significantly under loading, leading to a lower driving force of fatigue crack growth. The results reveal the overload retardation mechanism and the correlation between crack tip stress distribution and fatigue crack growth rate. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
Open AccessArticle Detecting Structural Features in Metallic Glass via Synchrotron Radiation Experiments Combined with Simulations
Metals 2015, 5(4), 2093-2108; doi:10.3390/met5042093
Received: 23 September 2015 / Revised: 29 October 2015 / Accepted: 3 November 2015 / Published: 9 November 2015
Cited by 5 | PDF Full-text (900 KB) | HTML Full-text | XML Full-text
Abstract
Revealing the essential structural features of metallic glasses (MGs) will enhance the understanding of glass-forming mechanisms. In this work, a feasible scheme is provided where we performed the state-of-the-art synchrotron-radiation based experiments combined with simulations to investigate the microstructures of ZrCu amorphous compositions.
[...] Read more.
Revealing the essential structural features of metallic glasses (MGs) will enhance the understanding of glass-forming mechanisms. In this work, a feasible scheme is provided where we performed the state-of-the-art synchrotron-radiation based experiments combined with simulations to investigate the microstructures of ZrCu amorphous compositions. It is revealed that in order to stabilize the amorphous state and optimize the topological and chemical distribution, besides the icosahedral or icosahedral-like clusters, other types of clusters also participate in the formation of the microstructure in MGs. This cluster-level co-existing feature may be popular in this class of glassy materials. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessArticle How Can Synchrotron Radiation Techniques Be Applied for Detecting Microstructures in Amorphous Alloys?
Metals 2015, 5(4), 2048-2057; doi:10.3390/met5042048
Received: 23 September 2015 / Accepted: 2 November 2015 / Published: 4 November 2015
Cited by 3 | PDF Full-text (710 KB) | HTML Full-text | XML Full-text
Abstract
In this work, how synchrotron radiation techniques can be applied for detecting the microstructure in metallic glass (MG) is studied. The unit cells are the basic structural units in crystals, though it has been suggested that the co-existence of various clusters may be
[...] Read more.
In this work, how synchrotron radiation techniques can be applied for detecting the microstructure in metallic glass (MG) is studied. The unit cells are the basic structural units in crystals, though it has been suggested that the co-existence of various clusters may be the universal structural feature in MG. Therefore, it is a challenge to detect microstructures of MG even at the short-range scale by directly using synchrotron radiation techniques, such as X-ray diffraction and X-ray absorption methods. Here, a feasible scheme is developed where some state-of-the-art synchrotron radiation-based experiments can be combined with simulations to investigate the microstructure in MG. By studying a typical MG composition (Zr70Pd30), it is found that various clusters do co-exist in its microstructure, and icosahedral-like clusters are the popular structural units. This is the structural origin where there is precipitation of an icosahedral quasicrystalline phase prior to phase transformation from glass to crystal when heating Zr70Pd30 MG. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessArticle Resistance of Hydrogenated Titanium-Doped Diamond-Like Carbon Film to Hyperthermal Atomic Oxygen
Metals 2015, 5(4), 1957-1970; doi:10.3390/met5041957
Received: 2 September 2015 / Revised: 2 September 2015 / Accepted: 14 October 2015 / Published: 23 October 2015
Cited by 1 | PDF Full-text (761 KB) | HTML Full-text | XML Full-text
Abstract
The effect of irradiation by a hyperthermal-atomic-oxygen beam on hydrogenated titanium-doped diamond-like carbon (hydrogenated Ti-DLC) films, applied as a solid lubricant for equipment used in low-earth orbit was investigated. Unlike the film thickness of hydrogenated non-doped DLC films, that of hydrogenated Ti-DLC films
[...] Read more.
The effect of irradiation by a hyperthermal-atomic-oxygen beam on hydrogenated titanium-doped diamond-like carbon (hydrogenated Ti-DLC) films, applied as a solid lubricant for equipment used in low-earth orbit was investigated. Unlike the film thickness of hydrogenated non-doped DLC films, that of hydrogenated Ti-DLC films was found to be constant after the films were exposed to atomic oxygen. In addition, bulk composition of the hydrogenated Ti-DLC film stayed constant, and in particular, hydrogen content in the film did not decrease. These results indicate that a hydrogenated Ti-DLC film can keep its low friction properties under vacuum. Surface chemical analysis showed that a titanium-oxide layer is form on the film by exposure to atomic oxygen. The thickness of the titanium oxide layer was estimated to be about 5 nm from the element distribution in the depth direction of the hydrogenated Ti-DLC films. The titanium-oxide layer was interpreted to protect the bulk film from erosion by hyperthermal atomic oxygen. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessArticle Characterization of Deformation Behavior of Individual Grains in Polycrystalline Cu-Al-Mn Superelastic Alloy Using White X-ray Microbeam Diffraction
Metals 2015, 5(4), 1845-1856; doi:10.3390/met5041845
Received: 3 September 2015 / Revised: 19 September 2015 / Accepted: 29 September 2015 / Published: 9 October 2015
Cited by 2 | PDF Full-text (872 KB) | HTML Full-text | XML Full-text
Abstract
White X-ray microbeam diffraction was applied to investigate the microscopic deformation behavior of individual grains in a Cu-Al-Mn superelastic alloy. Strain/stresses were measured in situ at different positions in several grains having different orientations during a tensile test. The results indicated inhomogeneous stress
[...] Read more.
White X-ray microbeam diffraction was applied to investigate the microscopic deformation behavior of individual grains in a Cu-Al-Mn superelastic alloy. Strain/stresses were measured in situ at different positions in several grains having different orientations during a tensile test. The results indicated inhomogeneous stress distribution, both at the granular and intragranular scale. Strain/stress evolution showed reversible phenomena during the superelastic behavior of the tensile sample, probably because of the reversible martensitic transformation. However, strain recovery of the sample was incomplete due to the residual martensite, which results in the formation of local compressive residual stresses at grain boundary regions. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessArticle Twinning-Detwinning Behavior during Cyclic Deformation of Magnesium Alloy
Metals 2015, 5(2), 881-890; doi:10.3390/met5020881
Received: 20 April 2015 / Revised: 12 May 2015 / Accepted: 18 May 2015 / Published: 26 May 2015
Cited by 7 | PDF Full-text (1101 KB) | HTML Full-text | XML Full-text
Abstract
In situ neutron diffraction has been used to examine the deformation mechanisms of a precipitation-hardened and extruded Mg-8.5wt.%Al alloy subjected to (i) compression followed by reverse tension (texture T1) and (ii) tension followed by reverse compression (texture T2). Two starting textures are used:
[...] Read more.
In situ neutron diffraction has been used to examine the deformation mechanisms of a precipitation-hardened and extruded Mg-8.5wt.%Al alloy subjected to (i) compression followed by reverse tension (texture T1) and (ii) tension followed by reverse compression (texture T2). Two starting textures are used: (1) as-extruded texture, T1, in which the basal pole of most grains is normal to the extrusion axis and a small portion of grains are oriented with the basal pole parallel to the extrusion axis; (2) a reoriented texture, T2, in which the basal pole of most grains is parallel to the extrusion axis. For texture T1, the onset of extension twinning corresponds well with the macroscopic elastic-plastic transition during the initial compression stage. The non-linear macroscopic stress/strain behavior during unloading after compression is more significant than during unloading after tension. For texture T2, little detwinning occurs after the initial tension stage, but almost all of the twinned volumes are detwinned during loading in reverse compression. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
Open AccessArticle An in situ Study of NiTi Powder Sintering Using Neutron Diffraction
Metals 2015, 5(2), 530-546; doi:10.3390/met5020530
Received: 27 February 2015 / Revised: 23 March 2015 / Accepted: 27 March 2015 / Published: 3 April 2015
Cited by 6 | PDF Full-text (1362 KB) | HTML Full-text | XML Full-text
Abstract
This study investigates phase transformation and mechanical properties of porous NiTi alloys using two different powder compacts (i.e., Ni/Ti and Ni/TiH2) by a conventional press-and-sinter means. The compacted powder mixtures were sintered in vacuum at a final temperature of
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This study investigates phase transformation and mechanical properties of porous NiTi alloys using two different powder compacts (i.e., Ni/Ti and Ni/TiH2) by a conventional press-and-sinter means. The compacted powder mixtures were sintered in vacuum at a final temperature of 1373 K. The phase evolution was performed by in situ neutron diffraction upon sintering and cooling. The predominant phase identified in all the produced porous NiTi alloys after being sintered at 1373 K is B2 NiTi phase with the presence of other minor phases. It is found that dehydrogenation of TiH2 significantly affects the sintering behavior and resultant microstructure. In comparison to the Ni/Ti compact, dehydrogenation occurring in the Ni/TiH2 compact leads to less densification, yet higher chemical homogenization, after high temperature sintering but not in the case of low temperature sintering. Moreover, there is a direct evidence of the eutectoid decomposition of NiTi at ca. 847 and 823 K for Ni/Ti and Ni/TiH2, respectively, during furnace cooling. The static and cyclic stress-strain behaviors of the porous NiTi alloys made from the Ni/Ti and Ni/TiH2 compacts were also investigated. As compared with the Ni/Ti sintered samples, the samplessintered from the Ni/TiH2 compact exhibited a much higher porosity, a higher close-to-total porosity, a larger pore size and lower tensile and compressive fracture strength. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)

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Open AccessReview Structural Dynamics of Materials under Shock Compression Investigated with Synchrotron Radiation
Metals 2016, 6(1), 17; doi:10.3390/met6010017
Received: 30 September 2015 / Revised: 4 December 2015 / Accepted: 9 December 2015 / Published: 15 January 2016
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Abstract
Characterizing material dynamics in non-equilibrium states is a current challenge in material and physical sciences. Combining laser and X-ray pulse sources enables the material dynamics in non-equilibrium conditions to be directly monitored. In this article, we review our nanosecond time-resolved X-ray diffraction studies
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Characterizing material dynamics in non-equilibrium states is a current challenge in material and physical sciences. Combining laser and X-ray pulse sources enables the material dynamics in non-equilibrium conditions to be directly monitored. In this article, we review our nanosecond time-resolved X-ray diffraction studies with 100-ps X-ray pulses from synchrotron radiation concerning the dynamics of structural phase transitions in non-equilibrium high-pressure conditions induced by laser shock compression. The time evolution of structural deformation of single crystals, polycrystals, and glass materials was investigated. In a single crystal of cadmium sulfide, the expected phase transition was not induced within 10 ns at a peak pressure of 3.92 GPa, and an over-compressed structure was formed. In a polycrystalline sample of Y2O3 stabilized tetragonal zirconia, reversible phase transitions between tetragonal and monoclinic phases occur within 20 ns under laser-induced compression and release processes at a peak pressure of 9.8 GPa. In polycrystalline bismuth, a sudden transition from Bi-I to Bi-V phase occurs within approximately 5 ns at 11 GPa, and sequential V–III–II–I phase transitions occur within 30 ns during the pressure release process. In fused silica shocked at 3.5 GPa, an intermediate-range structural change in the nonlinear elastic region was observed. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessReview In Situ Characterization Techniques Based on Synchrotron Radiation and Neutrons Applied for the Development of an Engineering Intermetallic Titanium Aluminide Alloy
Metals 2016, 6(1), 10; doi:10.3390/met6010010
Received: 30 November 2015 / Revised: 21 December 2015 / Accepted: 23 December 2015 / Published: 4 January 2016
Cited by 9 | PDF Full-text (2724 KB) | HTML Full-text | XML Full-text
Abstract
Challenging issues concerning energy efficiency and environmental politics require novel approaches to materials design. A recent example with regard to structural materials is the emergence of lightweight intermetallic TiAl alloys. Their excellent high-temperature mechanical properties, low density and high stiffness constitute a profile
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Challenging issues concerning energy efficiency and environmental politics require novel approaches to materials design. A recent example with regard to structural materials is the emergence of lightweight intermetallic TiAl alloys. Their excellent high-temperature mechanical properties, low density and high stiffness constitute a profile perfectly suitable for their application as advanced aero-engine turbine blades or as turbocharger turbine wheels in next-generation automotive engines. As the properties of TiAl alloys during processing as well as during service are dependent on the phases occurring, detailed knowledge of their volume fractions and distribution within the microstructure is of paramount importance. Furthermore, the behavior of the individual phases during hot deformation and subsequent heat treatments is of interest to define reliable and cost-effective industrial production processes. In situ high-energy X-ray diffraction methods allow tracing the evolution of phase fractions over a large temperature range. Neutron diffraction unveils information on order-disorder transformations in TiAl alloys. Small-angle scattering experiments offer insights into the materials’ precipitation behavior. This review attempts to shine a light on selected in situ diffraction and scattering techniques and the ways in which they promoted the development of an advanced engineering TiAl alloy. Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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Open AccessCorrection Correction: Liss, K.-D., et al. Hydrostatic Compression Behavior and High-Pressure Stabilized β-Phase in γ-Based Titanium Aluminide Intermetallics. Metals 2016, 6, 165
Metals 2017, 7(9), 353; doi:10.3390/met7090353
Received: 15 August 2017 / Accepted: 22 August 2017 / Published: 7 September 2017
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Abstract
The authors would like to apologize for any inconvenience regarding misleading errors and inconsistencies in some of the units and one number, and wish to make the following corrections to this paper [1]:[...] Full article
(This article belongs to the Special Issue Metals Challenged by Neutron and Synchrotron Radiation)
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