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Hydrogen-induced damage is an inevitable challenge in pipeline safety applications, especially, the fusion welded joints owing to microstructure heterogeneity caused by welding process. In this work, X100 pipeline steel was subjected to friction stir welding (FSW) at rotation rates of 300–600 rpm under water cooling, and the relationship among the microstructure, hydrogen diffusivity, and hydrogen embrittlement (HE) behavior of the nugget zone (NZ) were studied. The NZ at 600 rpm had the highest effective hydrogen diffusion coefficient (D eff) of 2.1 × 10−10 m2/s because of the highest dislocation density and lowest ratio of effective grain boundary. The D eff decreased with decreasing rotation rate due to the decrease of dislocation density and the increase of ratio of effective grain boundary, and the lowest D eff of 1.32 × 10−10 m2/s was obtained at 300 rpm. After hydrogen charging, the tensile strength of all specimens decreased slightly, while the elongation decreased significantly. As the rotation rate decreased, the elongation loss was obviously inhibited, and ultimately a lowest elongation loss of 31.8% was obtained at 300 rpm. The abovementioned excellent mechanical properties were attributed to the fine ferrite/martensite structure, low D eff , and strong {111}//ND texture dramatically inhibiting hydrogen-induced cracking initiation and propagation. • FSW of X100 steel was performed in water cooling, producing defect-free weld. • The diffusion behavior of hydrogen in the NZ was studies. • The effect of hydrogen on deformation and fracture behavior was analyzed. • The NZ with fine ferrite/martensite present high HE resistance. [ABSTRACT FROM AUTHOR]

Transport and loss of beam injected energetic particles (EPs) due to three-dimensional perturbations, associated with the external kink (XK) instability and fishbone-like mode (FLM), are numerically investigated utilizing the guiding center following code ORBIT for static toroidal plasmas in HL-2A. The perturbation structure for the XK is computed by the MARS-F code and then mapped to the Boozer coordinates as defined in ORBIT. The simulation shows that the EP profile experiences a significant change in the middle of the plasma column, when the XK-induced radial magnetic field perturbation amplitude, normalized by the equilibrium field, exceeds a threshold value of about 10 − 2 . The EP transport is found to be dominated by a diffusion process instead of convection. Furthermore, by scanning the perturbation frequency as a free parameter while maintaining the XK mode structure (thus mimicking the FLM as observed in DIII-D and JT-60U tokamaks), redistribution and loss of EPs are found to be substantially enhanced due to strong resonances between the FLM and EPs, when the mode frequency exceeds a threshold value of ∼2 kHz for the case considered. For either XK or FLM, the response of passing EPs to the perturbation is dominant due to the assumed tangential neutral beam injection. Most lost EPs due to these instabilities are initially passing particles but are eventually lost through trapped orbits. [ABSTRACT FROM AUTHOR]

In this work, the Al content-dependent microstructure evolution and oxidation behavior of co-sputtered CrAl alloyed coatings on Zr-4 alloy were systematically investigated in 1000 ℃ steam. Experimental results demonstrated that the microstructure of generated oxide scale transformed from a Cr 2 O 3 oxide layer with embedding discrete α-Al 2 O 3 particles at low Al contents to a continuous outer (α, θ)-Al 2 O 3 and inner Cr 2 O 3 bi-oxide layer at high Al contents. However, there appeared a unique eutectoid-like Cr 2 O 3 /α-Al 2 O 3 multilayered oxide scale in Cr-18.3Al coating, which conferred the sample with optimal oxidation resistance. The underlying oxidation mechanisms were rationalized by revealing the Al content dominated selective oxidation behavior. • Appropriate Al addition can improve the steam oxidation resistance of Cr coating. • Al content dependent microstructure transformation of oxide scale is revealed. • Unique Cr 2 O 3 /α-Al 2 O 3 multilayered oxide scale in Cr-18.3Al coating contributes to high oxidation resistance. • Oxide-scale structure dominated failure mechanisms of CrAl coatings are discussed. [ABSTRACT FROM AUTHOR]

Due to its service background, the thermal behavior of Ta films is substantially concerning to researchers, especially the heat-induced β-Ta to α-Ta phase transformation. In this work, the nanocrystalline Ta films with varying β/α phase ratios (0.85–0) were deposited and vacuum annealed at 200–800 °C to study the phase transformation behavior and mechanical properties. Partial phase transformation of β-Ta to α-Ta occurred at low temperature (200 °C) and complete transformation when the annealing temperature was raised to 800 °C. Moreover, an orientation relationship of β-<110>//α-<111> and β-{330}//α-{110} was concluded, and a hypothesis theory about the low-temperature phase transformation was proposed. Annealing hardening took place at 200–600 °C and softening at 800 °C in all the samples. The hardening is mostly due to the ordering of intergranular amorphous phases with the temperature increased, simultaneously bringing the increase of modulus. The annealing softening is governed by both grain coarsening and phase transformation, where the latter is dominated in high β fraction samples. • High-temperature induced grain boundary structure ordering promotes the hardening of Ta films at 200 °C–600 °C. • β-Ta to α-Ta phase transformation was found at a wide temperature range, which partially governs the softening of Ta at 800 °C. • A preferred orientation relationship of β-<110>{330}//α-<111>{110} was concluded • The influence of phase transformation on mechanical properties was independently quantified using a simple comparative method. [ABSTRACT FROM AUTHOR]

In this work, medium-Mn steel was friction stir welded and then intercritically annealed. Hydrogen diffusion and hydrogen embrittlement (HE) behavior in the nugget zone (NZ) were investigated. The as-welded NZ exhibited the highest HE index (HEI) of 79.2%, and hydrogen‑induced cracks propagated along the grain boundary, probably depending on grain boundary decohesion caused by H segregation. However, this condition was improved by post-welding annealing since fine lath reversed austenite, acting as a strong hydrogen trap, was introduced into the ferritic matrix, inhibiting the segregation of H to grain boundaries. Ultimately, the lowest HEI of 10.7% was obtained in the as-annealed NZ. • The austenite reversion kinetics in the NZ during post-welding intercritical annealing was simulated by DICTRA. • The behavior of hydrogen diffusion and embrittlement in the NZ were studied using H permeation tests and SSRT. • The behavior of H-induced cracks of the NZ was analyzed. • The lowest HEI of 10.7% was obtained in the as-annealed-620 NZ, much lower than that of the as-welded NZ. [ABSTRACT FROM AUTHOR]

With the monotonically increasing of W from 0 to 20 at. % in Ta-W films with Cr buffers, an abnormal phase evolution of α-Ta→β-Ta→α-Ta was found, which is due to the breaking and rebuilding of α-Ta nucleation. A small amount of W addition could disturb the epitaxial growth of α-Ta on Cr layers by refining the nucleus size. Nevertheless, as a completely miscible system, Ta-W solid solutions are preferred to possess the α-Ta structure. With the increasing W content, the nucleation barrier of α-Ta is correspondingly lower, facilitating the rebuilding of α-Ta growth. The effect of phase evolution competes with that of solid solution strengthening in the controlling mechanism of Ta-W hardness. The hardness of the sample with low W contents is largely influenced by the proportion of β-Ta, while the solid solution strengthening effect is more pronounced in high W. [Display omitted] [ABSTRACT FROM AUTHOR]

Ti-containing micro-alloyed steels are often alloyed with molybdenum (Mo) to reduce nano-precipitate coarsening, although the mechanism is still disputed. Using small angle neutron scattering we characterised the precipitate composition and coarsening of Ti-alloyed and Ti-Mo-alloyed steels. The results demonstrate ~25 at.% of Ti is substituted by Mo in the (Ti, Mo)C precipitates, increasing both the precipitate volume percent and average size. Mo alloying did not retard precipitation coarsening, but improved lattice misfit between precipitate and matrix, contributing to better ageing resistance of the Ti-Mo-alloyed steel. This new understanding opens opportunities for designing ageing-resistant micro-alloyed steels with lean alloying elements. Unlabelled Image [ABSTRACT FROM AUTHOR]

In order to quantify the fracture toughness and reveal the failure mechanism of crystalline/amorphous nanolaminates (C/ANLs), in-situ micro-cantilever bending tests were performed on Ag/Cu–Zr and Mo/Cu–Zr C/ANLs in a scanning electron microscope over a wide range of cantilever widths from several microns to the submicron scale. The results demonstrate that the fracture behavior was strongly influenced by sample size and constituent phases, respectively. The Ag/Cu–Zr micro-cantilevers failed in a ductile manner, with fracture toughnesses higher than the Mo/Cu–Zr samples that exhibited brittle failure. Both materials also displayed different cantilever width-dependences of fracture toughness. The Ag/Cu–Zr beams showed a fracture toughness that increases with the cantilever width, mainly due to a size-dependent constraining effect on the deformation of the crystalline phase. For the Mo/Cu–Zr beams, the fracture toughness decreased gradually to a low plateau as the cantilever width exceeded ∼1500 nm, which can be rationalized by a transition in stress condition. The underlying fracture mechanism of the Ag/Cu–Zr micro-cantilevers was identified as the interconnection of microcracks initiated in the amorphous Cu–Zr layers, compared to a catastrophically penetrating crack propagation in the Mo/Cu–Zr samples. The discrepancy in size-dependent fracture behavior between the two material systems is discussed in terms of plastic energy dissipation of ductile phases, crack tip blunting, crack bridging and the effect of strain gradient in the plastic zone on crack propagation. Image 1 [ABSTRACT FROM AUTHOR]

The medium-Mn steels with high strength and ductility can be used as a potential material in the engineering fields. However, the weld in the medium-Mn steel joint has extremely low ductility due to the existence of full martensite. In this work, a superior tensile strength of 1453 MPa and elongation of 32.7% was obtained in the weld of friction stir welded (FSWed) medium-Mn steel. This should be related to high volume fraction of austenite (24.4%) far higher than that of basal metal (15.1%). The formation mechanism of exceptionally high fraction of austenite was studied based on the transformation kinetics. The volume fraction of austenite in the weld predicted by classical model was only 15.4% much lower than the experimentally measured value, indicating that this model is not suitable for FSW. We applied various assumptions about the diffusivity of Mn in austenite and ferrite during simulation. Consequently, when the Mn diffusivity of austenite and ferrite was multiplied by 4000 and 1500 times, respectively, the simulated austenite volume fraction was well consistent with the experimental results. This was attributed to that the high density of dislocations introduced by strong plastic deformation of FSW promoted the Mn diffusion and the austenitic reverse transformation. • The weld contained a high volume fraction of austenite (24.4%) far higher than that of the basal metal. • The formation mechanism of exceptionally high fraction of austenite was studied based on the transformation kinetics. • A superior tensile strength of 1453 MPa and elongation of 32.7% was obtained in the weld of FSW medium-Mn steel. • The contribution of various strengthening mechanisms to yield strength was evaluated. [ABSTRACT FROM AUTHOR]

Abstract The microstructural features and hardness of He-irradiated miscible Cu/Zr crystalline/crystalline nanolaminates with a negative enthalpy of mixing were investigated at room temperature. The distribution of He bubbles within the Cu layers exhibits a high dependence on both layer thickness (h) and ion dose (Φ), while that at the Cu-Zr interfaces is only affected by ion dose. Compared with their as-deposited counterparts, the He-irradiated Cu/Zr nanolaminates tend to manifest radiation-induced solid-state amorphization (RSA), which was induced by ion beam mixing and initiated from crystalline interfaces. The size-dependent hardness of the as-deposited Cu/Zr nanolaminates is elucidated by a transition in the strengthening mechanism from the interfacial barrier strengthening mechanism to the confined layer slip of partials when h is increased. In the He-irradiated Cu/Zr samples, however, the size-dependent hardness is highly related to Φ. Under lower Φ , a nonmonotonically h -dependent irradiation hardening is evident and is associated with a transition from irradiation hardening at large h (≥10 nm) to softening at small h (<10 nm), and the maximum hardening occurs at a critical value of h ≈ 25 nm. In contrast, under higher Φ , the Cu/Zr nanolaminates merely display irradiation softening behavior, with the minimum softening at the critical value of h ≈ 25 nm. The underlying mechanisms are highlighted in terms of dislocation-bubble interactions and RSA. These findings indicate the effects of He ion dose and layer thickness on the He bubble distribution and the interface-mixing of Cu/Zr nanolaminates as well as provide thorough insight into how to tune the He ion dose to manipulate the mechanical response of nanolaminated FCC/HCP materials on a small scale. Graphical abstract Unlabelled Image Highlights • Cu/Zr nanolaminates with smaller layer thickness showed enhanced radiation tolerance. • Large ion dose enhances bubble diameter while reduces bubble spacing in Cu layers. • Cu/Zr nanolaminates suffered size- and dose-dependent amorphization at interfaces. • Low ion dose induces irradiation hardening, while high ion dose induces softening. [ABSTRACT FROM AUTHOR]

Abstract The fragmentation and interfacial stress transfer of Cu 75 Zr 25 amorphous films with varying film thickness (h) on polyimide substrates were systematically investigated by using uniaxial tensile testing, in combination with in situ optical microscope and atomic force microscope characterizations. It is revealed that the interfacial stress transfer length increases monotonically as h increases. The interfacial stress transfer mechanism changes from elastic-plastic to approximately linear elastic at a critical point of h = 250 nm. This is related to h -dependent deformation-induced devitrification (DID) near the interfaces that the thinner Cu-Zr amorphous films display more DID. This study elucidates for the first time the effect of DID on the interfacial stress transfer, which will be helpful to design the interface with desired property for nanotechnological applications. Highlights • Fragmentation and interfacial stress transfer of Cu-Zr amorphous films were studied. • Interfacial stress transfer length increases as film thickness increases. • Thinner Cu-Zr amorphous films display more deformation-induced devitrification. • A crystallization gradient is induced by deformation along the film growth direction. • Interfacial stress transfer changes from elastic-plastic to linear elastic. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Novel tensile tests with applied external magnetic field were performed. • The magnetic field has minimum effect on the tensile properties of Eurofer-97. • No change in the fracture surface is observed. • The importance of performing creep tests with magnetic fields is discussed. Abstract Eurofer-97 is the main structural material targeted for the EU DEMO fusion tokamak and will be exposed to magnetic fields up to ˜10 T during operation. It is therefore necessary to understand the effect of magnetic fields on the mechanical properties of the Eurofer-97. We perform 30 uniaxial tensile tests with and without a transverse 1.5 T magnetic field at room temperature. Statistical results reveal that the magnetic field increases the value of proportionality limit by ˜2.6% (from 514 ± 4.5 MPa to 528 ± 10 MPa), but has minimum (<1%) effect on the ultimate tensile strength and elongation of this Eurofer-97. No clear change in the fracture surface is observed. [ABSTRACT FROM AUTHOR]

Highlights • The Sm(Co bal Fe x Cu 0.06 Zr 0.025) z magnets with different Fe content and z value were investigated. • The correlation of Fe content and z value was established to achieve excellent magnetic properties. • Increasing Fe content promoted the irreversible microstructure evolution in magnets. • Magnetic domain patterns of magnets affected by increasing Fe content indirectly. Abstract Correlation between Fe content and z value on the structural and magnetic properties of the Sm(Co bal Fe x Cu 0.06 Zr 0.025) z magnets (x = 0.20, 0.25, 0.28, and z = 7, 9.5) has been investigated. It is found that the cellular phases in the magnets grow up with increasing Fe content, so the cell boundary phases could hardly form well without enough Sm atoms, resulting in coercivity decreasing. After supplement of Sm content by decreasing z value, cell boundary phases formed continuously, and coercivity was strongly enhanced due to the remarkable concentration gradient of Cu between the 1:5H cell boundary phase and 2:17R cellular phase. It is thus suggested that as the Fe content increases, the z value of magnets need reducing simultaneously in order to keep high coercivity of the magnets. [ABSTRACT FROM AUTHOR]

Highlights • In situ study on the buckling and post-buckling of Cu–Zr amorphous films. • A unique buckling and post-buckling behavior is observed. • A buckling map has been developed, including four buckling modes. • Formation of buckling modes are related to the size-dependent deformation. Abstract The buckling and post-buckling behavior of the Cu–Zr amorphous films is highly dependent on film thickness (h) and applied strain (ε). A buckling map has been developed with h and ε as axes, where four buckling modes are detected, including uncracked triangular buckle, cracked rectangular buckle, cracked triangular buckle, and patches. Formation of the four buckling modes will be discussed in terms of the film thickness and size-dependent deformation. [ABSTRACT FROM AUTHOR]

Highlights • Model-I crack of a long rectangular superconducting slab under thermal effect is investigated. • Stress intensity factors of the slab during the field decent of pulsed field magnetization and field cooling are calculated. • For the field cooling, temperature rise causes the stress intensity factor to decrease. • For pulsed field magnetization, there exists a peak value of stress intensity factor. Abstract Superconducting cables made of high-temperature superconductors have great potential applications in space solar power station. Since the critical current density of high temperature superconductor is dependent of temperature and determines the distribution of the magnetic flux density, temperature change can affect the pinning force. In this paper, model-I crack problem of a long rectangular superconducting slab under thermal effect is investigated. The stress intensity factors of the slab during the field decent of pulsed field magnetization (PFM) and field cooling (FC) are calculated. Compared with that without considering thermal effect, the result shows that once the temperature of the slab rises, the variation of the stress intensity factor will have a peak during the applied magnetic field decent for the PFM. While for the FC, temperature rise causes the stress intensity factor to decrease. [ABSTRACT FROM AUTHOR]

In this paper experimental investigation was conducted on 20 aluminum alloy bolted joints. Based on the tests, three-dimensional refined finite element models were built and verified by the experimental results. By the FE model, extensive parametric analysis was carried out to clarify the influence of aluminum alloy material types (6061-T6, 6063-T5, 6082-T6 and 7A04-T6 which is a kind of ultra-high strength aluminum alloy applied in engineering structures), the diameter of bolt hole and the length of long bolted joints on the loading capacity of aluminum alloy bolted connection. The test results showed that the current design codes including EC9, AA 2010 and GB 50429-2007 underestimate the bearing strength of the joint. According to the results of parametric analysis, a new design method considering the difference of material types was proposed and fit better with the data points than the methods in current specifications; a more precise and detailed suggestion for the bolt hole diameter in aluminum alloy bolted joints was also given. The paper proposed a theoretical model to explain the mechanical mechanism of long bolted joints and gave a new design method for reduction factors of bolt shear force in long joints with different materials of plate and different materials of bolt. [ABSTRACT FROM AUTHOR]

Nanostructured face-center-cubic/body-center-cubic Cu/(NbMoTaW) multilayers were prepared with equal layer thickness ( h ) spanning from 5 to 100 nm. The hardness was found to increase with reducing h to ~50 nm, following the Hall–Petch relation. Below this critical thickness, a hardness plateau emerged indicative of an interface barrier strengthening mechanism. The high density of misfit dislocations at interfaces facilitates the yielding of high entropy alloy NbMoTaW layers at stresses far less than the strength of Cu/(NbMoTaW) estimated by rule-of-mixture. Compared with reported multilayers, the present Cu/(NbMoTaW) samples show the size-independent hardness at a larger size-range h  < 50 nm. [ABSTRACT FROM AUTHOR]

Microcompressive tests were performed to investigate the intrinsic modulation effect and extrinsic diameter effect on strength and deformation behaviors of nanolaminated Cu/Cu-Zr crystalline/amorphous micropillars within a diameter D range from 300 to 1500 nm as well as a modulation ratio η range from 0.1 to 3.0. Experimental results revealed a transition of D -dependent deformation mode from homogeneous-like to shear localization at large η , while D -independent homogeneous extrusion of Cu at small η . Furthermore, the flow strength increased with raising D at small η , but decreased at large η , exhibiting a D -insensitive strength at a critical η* ~ 0.5. These unusual results were rationalized in terms of a coupling effect of dislocation actions and shear transformation zone mediated operations. [ABSTRACT FROM AUTHOR]

The objective was to determine effects of tail docking on carcass characteristics and meat quality of fat-tail lambs. We tested the hypothesis that tail-docked lambs have greater fat content in their muscle and meat, and their carcass has better nutritional quality. Twenty lambs were randomly allocated into two groups, Control and Tail docked (application of rubber ring distal end of the caudal fold at 1 d of age). All lambs grazed on pasture (weaned at 46 d of age) until they were slaughtered at 6 mo. The longissimus dorsi (LD) and gluteus maximus (GM) muscles were collected and the carcass evaluated. Carcass weight, dressing percentage, average daily gain (P < 0.001), eye muscle area (P < 0.05), back fat thickness, rump fat weight, and rumen epiploic fat weight (P < 0.001) were increased in Tail-docked lambs, as were intramuscular fat (IMF, P < 0.01) and the L * value (P < 0.05). Furthermore, in Tail-lambs lambs, there was decrease in hue angle ( H° ) value (P < 0.05) of the LD muscle. In addition, shear force (P < 0.001) of LD muscle, drip loss (P < 0.001) of the LD muscle and shear force (P < 0.01) of the GM muscle were decreased in Tail-docked lambs. Most saturated fatty acids (SFA) were affected by tail docking, except C16:0, C18:0 and C20:0. For monounsaturated fatty acids (MUFA), concentrations of C16:1 (P < 0.01) and C18:1n-9 (P < 0.001) were higher in Tail-docked lambs, as were concentrations of C18:3n-3, SFA and n-3. However, polyunsaturated fatty acid (PUFA), concentrations of C18:2n-6, C20:3n-6 and C20:4n-6, PUFA, n-6, PUFA/SFA and n-6/n-3 ratios were all lower (P < 0.01) in Tail-docked lambs. In conclusion, as expected, in Tail-docked lambs, tail fat was re-directed into muscle; therefore, tail docking improved meat quality, although it reduced PUFA concentrations and increased SFA concentrations in meat. [ABSTRACT FROM AUTHOR]

The correlation between preparation conditions and microstructure as well as magnetic properties were studied for Sm(Co 0.665 Fe 0.25 Cu 0.06 Zr 0.025 ) 7 magnets. Increase of sintering temperature from 1468 to 1493 K promotes the amalgamation of small grains into big ones, resulting in an enlargement of average grain size from 10 to 25 μm and diffusion of Cu from inner grains to Cu-lean grain boundaries. As a result, the demagnetization curve squareness of the magnets improves substantially, leading to a remarkable enhancement of the maximum energy product from 21.3 to 27.1 MGOe. The coercivity of the magnets drops from 25.3 to 16.0 kOe at the same time, which was verified by the increase of the average domain width from 1.1 μm in small grains to 2.5 μm in big grains. It is therefore concluded that tuning of the preparation conditions causes a more homogeneous distribution of Cu, which is crucial for the improvement of magnetic properties. [ABSTRACT FROM AUTHOR]

Elastic follow-up is a mechanical boundary condition lying between constant load and constant strain control. It exists in many engineering components operating at high temperature and can result in dramatically different creep stress relaxation and strain accumulation rates in a localized region of a component. We have performed creep tests under constant load, constant strain and elastic follow-up control on an aged (additional 22,000 h) 316H austenitic stainless steel after service in a nuclear power station for 65,000 h. Primary and secondary forward creep models with parameters derived from the constant-load data were able to describe constant-load creep adequately, but not able to predict stress relaxation and elastic follow-up. We show that this is because ageing has increased the constant-load creep strain rate significantly but has no effect on stress relaxation creep strain rate. Ageing promotes the formation of ferrite/chi phase at grain boundaries which are preferential sites for creep cavitation under load control. However, creep cavitation is less likely under constant strain and elastic follow-up control because a high creep strain rate, large creep strain and stress cannot coexist under these boundary conditions. [ABSTRACT FROM AUTHOR]

Microstructure modification induced giant coercivity enhancement from 950 to 1688 kA/m has been achieved in Sm(Co 0.665 Fe 0.25 Cu 0.06 Zr 0.025 ) 7 permanent magnets via Cu powders doping. Microstructure observation shows that in original magnet there are Cu-lean regions along the grain boundary area, where regular cellular structure does not form. After Cu powders doping, most Cu-lean regions disappear. Comparison of magnetic domain reversal between the original magnet and doped magnet indicates that reversed domain propagation was substantially restrained due to the elimination of the Cu-lean region. Moreover, the pinning field increases by 83.3% after Cu doping, having good agreement with coercivity enhancement. [ABSTRACT FROM AUTHOR]

Interphase precipitation (IPP) of nanoscale carbides in a vanadium-containing high-strength low-alloy steel has been investigated. Small angle neutron scattering (SANS) and transmission electron microscopy (TEM) were employed to characterize the precipitates and their size distributions in Fe-0.047C-0.2V-1.6Mn (in wt.%) alloy samples which had been austenitized, isothermally transformed at 700 °C for between 3 and 600 min and water quenched. TEM confirms that, following heat treatment, rows of vanadium-containing nanoscale interphase precipitates were present. Model-independent analysis of the nuclear SANS signal and model fitting calculations, using oblate spheroid and disc-shapes, were performed. The major axis diameter increased from 18 nm after 3 min to 35 nm after 600 min. Precipitate volume percent increased from 0.09 to 0.22 vol% over the same period and number density fell from 2 × 10 21 to 5 × 10 20 m −3 . A limited number of measurements of precipitate maximum diameters from TEM images showed the mean value increased from 8 nm after 5 min to 28 nm after 600 min which is in reasonable agreement with the SANS data. [ABSTRACT FROM AUTHOR]

Experimental investigation was conducted on large-section extruded aluminum alloy columns of I-section and rectangular hollow section (RHS). Altogether seven columns with different slenderness ratios were comprised. The failure modes and stability resistance as well as load-displacement responses were identified. It was found that all tested specimens failed in flexural buckling. An extensive parametric analysis on 180 specimens was carried out with general FEA software ANSYS to evaluate the reliability level of the current design specifications including American aluminum design manual, Eurocode 9 and Chinese code GB 50429. The design stability resistance advised by Eurocode 9 and Chinese code GB 50429 is conservative, while that of American aluminum design manual slightly overestimates the practical stability resistance. Based on the parametric analysis results, a new design method was proposed to improve the design accuracy. [ABSTRACT FROM AUTHOR]

SiC fiber-reinforced Ti-21Al-29Nb matrix composites with either C and C/Mo duplex coatings were prepared by the foil-fiber-foil (FFF) method, in order to comparatively study the effects of C/Mo duplex coatings on the interface and mechanical properties of the composites. The longitudinal tensile strength of the as-prepared composites was measured at room temperature. In order to study the interfacial thermal stability and microstructure evolution characteristics of the composites, vacuum thermal exposures of the composites were carried out at 800, 900 or 940 °C for different durations. The interfacial microstructures of the as-prepared and thermally-exposed composites were investigated by means of scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS). The results indicate that the C/Mo duplex coating does not only have better thermal stability, but also can further slow down the interfacial reaction of the composites in comparison with the C single coating. The diffusion of a small amount of Mo atoms made the matrix close to the interface have better plasticity, so the tensile strength of the composites can be further improved. The interface of the composite with the C/Mo duplex coating was nearly intact after the 940 °C/50 h thermal exposure while that of the composite with the C single coating was not intact, as the C/Mo duplex coating can better relax the thermal residual stresses than the C single coating. [ABSTRACT FROM AUTHOR]

Deuterium (D) retention in polycrystalline tungsten (W) with copper (Cu) ion damage concurrently produced at elevated surface temperature is investigated. An in situ heated stage held W samples at a controlled temperature up to 1243 K, which were subjected to displacement damage produced by 3.4 MeV Cu ions. D retention is subsequently explored by exposure of the W samples held at 383 K to a D 2 plasma ion fluence of 10 24 D + /m 2 . Nuclear reaction analysis (NRA), utilizing the D( 3 He,p) 4 He nuclear reaction, is used to probe the D concentration in the near surface up to 6 μ m. Thermal desorption spectroscopy (TDS) is used to measure outgassed HD and D 2 molecules to determine the bulk D concentration. Both NRA and TDS measure a significant reduction in D retention for samples damaged at elevated temperature. TDS quantitatively shows that the lowest energy trap remains largely unaffected while higher energy traps, induced by Cu ions, are annealed and approach intrinsic concentrations as the temperature during ion damage approaches 1243 K. Analysis of TDS data yields an activation energy of (0.10 ± 0.02) eV for recovery of ion-damage induced traps at elevated temperature. [ABSTRACT FROM AUTHOR]

The compressive buckling behaviour of extruded aluminium alloy I-section columns with fixed-pinned end conditions has been experimentally and numerically investigated in this study. A total of 11 column tests, involving two heat-treated aluminium alloys – 6061-T6 and 6063-T5, were carried out to acquire the compressive buckling strengths. Prior to the column tests, material properties of the two aluminium alloys were determined from tensile coupon tests, while the initial local and global geometric imperfections were separately measured by means of experimental techniques. By using the ABAQUS software package, finite element (FE) models that could account for material non-linearity and initial geometric imperfections were developed. The FE models were further validated against the test results, enabling reliable simulation of the compressive buckling behaviour of the tested columns with fixed-pinned end conditions. Based on the obtained test and numerical results, the calculation methods in the current design standards, including the European, Chinese, American and Australian/New Zealand specifications, were all assessed. It was shown that the design provisions in all the four standards provided relatively conservative strength predictions, especially for the aluminium alloys with more pronounced strain hardening capacity. [ABSTRACT FROM AUTHOR]

Bacterial spot of tomato ( Solanum lycopersicum L.) caused by several Xanthomonas species is one of the most destructive diseases. Genes regulating the hypersensitive resistance and field resistance to X. perforans race T3 have been intensively investigated over the last decade. However, a comparative analysis of cellular responses to the pathogen in susceptible and resistant hosts has not been completed, which prevents the detailed understanding of the interactions between the pathogen and tomato plants. In this study, the characteristics of lesions, stomata, and pathogen colonization in hypersensitive response (HR) PI 128216, field-resistant PI 114490, and susceptible OH 88119 tomato plants after inoculation with green fluorescent protein-labeled X. perforans race T3 bacteria were investigated. Significant differences in developmental processes and the micromorphology of spot lesions among three tomato lines were observed. Our results suggested that the faster lesion development in OH 88119 plants compared with that of the other two lines was associated with a greater increase in the stomatal apertures over a longer period following bacterial inoculation. The depth of bacterial colonization and pathogen density inside infected leaves in OH 88119 were also significantly different from that of resistant tomato plants. Determination of the ultrastructural responses to X. perforans among three tomato lines revealed that cell wall defense response was the main difference between resistant and susceptible tomato lines. These results may provide fundamental information for understanding the cellular and molecular mechanisms regulating tomato responses to X. perforans race T3. [ABSTRACT FROM AUTHOR]

The high Mn steel (Mn ≥ 20 wt.%) is widely applied because of excellent cryogenic properties. In the fusion-welded high-Mn steel joint, the Mn vapor and segregation degrade the joint quality. Friction stir welding (FSW) produces a high-Mn steel joint without defect, but the nugget zone (NZ) exhibits a poor plasticity. In this work, the preheating was subjected to FSW high-Mn steel to improve the plasticity of the NZ. Compared with the as-welded NZ, the as-preheated NZ contained slightly coarser austenite with lower density of dislocations (6.7 × 1014 m−2), and had a lower stacking fault energy (SFE) (47.18 mJ m−2) at room temperature. The lower SFE caused the deformation mechanism of dislocation slip and active twinning-induced plasticity (TWIP) in the as-preheated NZ owing to the lower back stress and critical twinning stress. Subsequently, a high strength and plasticity product of 62 GPa% was achieved in the as-preheated NZ, which was consistent with high strain hardening rate. At cryogenic temperature of −196 °C, the SFE of the as-preheated NZ decreased to 35.66 mJ m−2, but more active TWIP besides dislocation slip was found during tension. Therefore, the as-preheated NZ exhibited excellent strength and plasticity product of 91.9 GPa%. Furthermore, the yield strength of the as-preheated NZ was slightly reduced, which was attributed to the decreased of dislocation density and grain growth. • The preheating was introduced into the friction stir welded high Mn steel. • The SFE of austenite in the as-welded and as-preheated NZs at room and cryogenic temperature was calculated. • The deformation behavior of the as-welded and as-preheated NZs at room and cryogenic temperature was studied. • The contribution of various strengthening mechanisms to yield strength was evaluated. • The as-preheated-320 NZ presented excellent strength and plasticity product at room and cryogenic temperature. [ABSTRACT FROM AUTHOR]

An experimental program including study has been conducted to investigate buckling behavior of 7A04 high-strength (HS) aluminum alloy columns under axial compression, in which 42 L-shaped extruded specimens were designed and tested. The specimens involved two sections and seven slenderness ratios varying from 15 to 100. The test results were compared with design results in accordance with American Aluminum Design Manual, GB 50429-2007 and Eurocode 9. A finite element (FE) model of the tested specimens under axial compression has been developed by using general finite element software ANSYS, and was verified by using the test results reported herein and other experimental results presented in the literature. By using this FE model, an extensive body of parametric analyses were conducted to clarify the effects of width-to-thickness ratio of angle legs, initial imperfections and material strengths on the buckling resistance of the 7A04 angle columns. Based on the test and FE analyses results, a modified design method was proposed for predicting the buckling resistance of 7A04 high-strength aluminum alloy columns more accurately. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation on local buckling behavior of extruded 6000 series alloy I-shaped aluminium alloy beams. A total of 10 specimens with a wide range of width-to-thickness ratios (4.4–15.0 of flange, 42.9–73.1 of web) of component plates were divided into two types: one with stiffeners at mid-span, and the other without intermediate stiffeners. Failure modes, ultimate loading capacities, load-deformation responses and load-strain curves of the specimens were studied. Local buckling occurred in the top flange and web of six specimens without intermediate stiffeners, and shear local buckling occurred in the other four specimens with intermediate stiffeners though which developed a tension field. A finite element model was developed and validated against the test results, which was used for parametric analysis of 24 specimens. The investigation focused on the effects of the intermediate stiffeners and width-to-thickness ratio on the buckling strength of the aluminium alloy beams. It was found that component plates with small width-to-thickness ratios could make material function to its fullest potential; And there was a significant increase in the post-buckling strength; Eurocode 9 underestimated the loading capacity of the specimens to be safe. For the specimens with thin (width-to-thickness ratio more than 40) web, the standards should be especially enhanced. Calculation results of the finite element model consist well with the experimental results. [ABSTRACT FROM AUTHOR]

Electroreduction of water into hydrogen holds promise to deal with growing environmental pollution and energy crisis, but it relies on efficient catalysts for both hydrogen/oxygen evolution reaction, that normally contain precious metal. Here, based on first principles calculations, we identify Co-anchored α-In 2 Se 3 as a bifunctional catalyst that can operate for both hydrogen/oxygen evolution reaction. The chemical activity can be largely enhanced or optimized by electrostatic potential due to the polarization, even better than traditional one containing precious metal. Both hydrogen/oxygen evolution reaction are dependent on polarization direction of α-In 2 Se 3 and could occur on different polarization domains separately of α-In 2 Se 3 , that providing a way for future design of bifunctional catalysts without precious metals based on two-dimensional ferroelectric substrate. • The effect of polarization for the HER and OER activity of Co atom supported on α-In 2 Se 3 has been investigated by DFT. • The activity of TM atom can be largely enhanced or optimized by electrostatic potential due to the polarization. • The stability of the single atom catalysts and the mechanism for enhancing catalytic reactions have been fully discussed. [ABSTRACT FROM AUTHOR]

The medium-Mn steels have a great application potential in the engineering fields due to its excellent strength and toughness. However, the presence of coarse martensite and segregation of Mn in the fusion-welded medium-Mn steel joint severely deteriorated toughness and ductility. In this work, 6 mm thick medium-Mn steel plates were joined by friction stir welding, and then were intercritically annealed to enhance the toughness and ductility of the joint. The as-welded nugget zone (NZ) contained lath martensite with low proportion of high angle boundaries (HABs), leading to the joint with lower elongation of 22.5% and the impact energy of 73.6 J/cm2. However, the as-annealed NZ consisted of ferrite and austenite because partial martensite changed to reversed austenite, while other martensite became ferrite during annealing. In addition, the proportion of HABs in the as-annealed NZ increased obviously. In comparison with as-welded joint, the impact energy and elongation of the as-annealed joint was increased by 70.7% and 44.4%, respectively. The abovementioned excellent mechanical properties were attributed to the high proportion of HABs and a large amount of ultra-fine reversed austenite with high thermal and mechanical stability, which provided a significant transformation induced plasticity effect, obviously inhibiting crack initiation and propagation. This systematic work provided a reference for welding similar materials containing retained austenite. [ABSTRACT FROM AUTHOR]

This work evaluates the effectiveness of using forward creep deformation laws to predict the observed relaxation behaviour of 316H austenitic stainless steel. A summary of empirical creep methods, forward and stress relaxation experimental data were given. A primary and secondary creep strain rate (RCC-MR) model and an average creep strain rate model are combined with derived material constants to predict a group of stress relaxation tests at temperatures from 475 °C to 600 °C. The RCC-MR primary creep model predicted the stress relaxation behaviour soundly and the average creep strain rate model underestimated all of the stress relaxation data. The difference between stress relaxations predicted using strain hardening and time hardening versions of the RCC-MR equations are small. Factors affecting the predictions; including limitations in data range, data scatter, selection of a forward creep model, application of a forward model to stress relaxation and difference between forward creep and stress relaxation and are discussed. [ABSTRACT FROM AUTHOR]

The hardness, tensile ductility, and strain rate sensitivity of crystalline Cu/amorphous Cu–Zr nanolaminates (Cu/Cu–Zr C/A NLs) have been measured as a function of modulation ratio ( η ). With reducing η , the tensile ductility first decreased and subsequently increased, leaving a minimum value at η ∼ 1.0. However, the strain rate sensitivity ( m ) increased monotonically with reducing η and spanned from a negative value at η over ∼1.0 to a positive one at η below ∼1.0, indicating a tunable strain rate sensitivity in engineered C/A NLs. Careful microstructural examinations reveal that a deformation-induced devitrification (DID) in the amorphous nanolayers is the key factor responsible for the aforementioned experimental phenomena. For thinner amorphous nanolayers, the DID becomes more intense. The size-dependent DID drives the pure Cu–Zr amorphous single layer films to (i) exhibit a thickness-dependent tensile ductility opposite to that of pure Cu single layer films, and (ii) have a negative m contrary to the positive m in their pure Cu counterpart. When the two layers are engineered into C/A NLs, a competition exists between the two inverse constituent nanolayers. This competition is strongly η- dependent, resulting in a non-monotonic evolution in tensile ductility and significant change in m when η spans from 9.0 to 0.1. The fracture mode of the C/A NLs transformed from shearing at small η to opening at large η ; this can be rationalized by considering the competition between the two constituent nanolayers as a microcrack initiator. In addition, the strengthening mechanisms of the C/A NLs were analyzed and the η -dependent hardness was quantitatively described using a modified mechanistic model. [ABSTRACT FROM AUTHOR]

The local–overall interactive buckling behaviour of welded stainless steel I-section columns was experimentally and numerically examined in this study. A total of ten test specimens were fabricated from hot-rolled stainless steel plates and axially loaded between two pin-ended supports. The specimens failed by local–overall interactive buckling about the minor axis. Prior to the member testing, material properties, residual stresses and initial local and global geometric imperfections were all accurately determined. Detailed finite element (FE) models, capable of simulating the interactive buckling behaviour and predicting the ultimate capacity of welded stainless steel I-section columns, were validated against the obtained test results. The validated FE models were subsequently used to carry out systematic parametric studies, exploring the influences of the key input parameters, including the welding residual stresses, initial geometric imperfections, material properties and slenderness ratios. The generated test and numerical results were then used to assess the accuracy of a series of existing design methods: Eurocode 3 Part 1.4 and the design proposal of Rasmussen and Rondal, both of which employ the effective width concept, and the two separate design proposals of Becque et al. in the EN 1993-1-4 and AS/NZS 4673 formats and the proposal of Huang and Young, all of which are based on the direct strength method (DSM). Based upon the assembled data points, two separate design curves are proposed herein for austenitic and duplex stainless steels, which have been demonstrated to offer very accurate strength predictions for welded stainless steel I-section columns undergoing interactive buckling. [ABSTRACT FROM AUTHOR]

We create a model for H retention depth profiles in W and subsequently model how this profile changes after isotope exchange. This is accomplished by calculating how trapping defects in W accumulate D (or H) inventory as W is being exposed to plasma. Each trapping site is characterized by a trapping rate and a release rate, where the only free parameters are the distribution of these trapping sites in the material. The filled trap concentrations for each trap type are modeled as a diffusion process because post-mortem deuterium depth profiles indicate that traps are filled well beyond the ion implantation zone (2–5 nm). Using this retention model, an isotope exchange rate is formulated. The retention model and isotope exchange rate are compared to low temperature isotope exchange experiments in tungsten with good agreement. The limitations of the current model highlight important physics and motivate future work. [ABSTRACT FROM AUTHOR]

Nanoindentation methodology was used to measure the hardness, strain rate sensitivity (SRS) and activation volume of Cu/Cu–Zr crystalline/amorphous nanolaminates (C/ANLs) with layer thickness ( h ) spanning from 2.5 to 150 nm before and after He ion-implantation at room temperature. It is interestingly to uncover that the ion radiation-induced devitrification (RID) occurs in the glassy Cu–Zr nanolayers, in which the nanocrystallites transit from the Cu 10 Zr 7 intermetallics at large h to the fcc Cu–Zr solid solution at small h . Compared with the as-deposited Cu/Cu–Zr C/ANLs associated with monotonic increase in hardness and SRS (or a monotonic decrease in activation volume) with reducing h , the irradiated Cu/Cu–Zr manifested enhanced hardness in the form of two hardness plateau and an unexpected non-monotonic variation in SRS (similarly in activation volume). It was clearly unveiled that the SRS of irradiated Cu/Cu–Zr firstly decreased with reducing h down to a critical size of ∼50 nm and subsequently increased with further reducing h to ∼10 nm, below which a SRS m plateau emerges (The activation volume of irradiated Cu/Cu–Zr had exactly an opposite variation). These phenomena are rationalized by considering a competition between dislocation-interface and dislocation-bubble interactions. A thermally activated model based on the depinning process of bowed-out dislocations pinned by obstacles was employed to quantitatively account for the variation of SRS with h in Cu/Cu–Zr C/ANLs before and after radiation. Our findings not only provide fundamental understanding of the effects of radiation-induced defects on plastic characteristics of C/ANLs, but also offer guidance for their microstructure sensitive design for performance optimization at extremes. [ABSTRACT FROM AUTHOR]

A comprehensive experimental programme has been carried out to investigate the local buckling and postbuckling strengths of aluminium alloy I-section stub columns. A total of 15 test specimens made of two heat-treated aluminium alloys (6061-T6 and 6063-T5) were fabricated by extrusion. The material properties were acquired by the tensile coupons cut directly from the extruded cross-sections. The local geometric imperfections in sections were accurately measured prior to the tests. The stub column specimens were tested under axial compression between two fixed end supports, during which the local plate buckling featured visibly for each test specimen before reaching the peak load. The critical local buckling strengths were determined from the measured out-of-plane deflections and surface strains corresponding to the plate elements, which were further compared with the theoretical and analytical values taking into account element interaction and material non-linearity. Based on the obtained experimental postbuckling strengths, the design provisions in current design standards, including the American, Australian/New Zealand, European and Chinese specifications, were all evaluated. It was revealed that the predicted compressive strengths from the four design standards were generally conservative, especially for the cross-sections made of aluminium alloys with pronounced strain hardening properties. [ABSTRACT FROM AUTHOR]

A permanent magnetic yoke with a straight air gap was developed as the magnetic excitation unit, in order to improve the efficiency of magnetorheological (MR) polishing for ultra-smooth surface planarization. Finite element modelling was used to simulate the magnetic performance of the newly developed yoke, which was found to agree well with the experimental measurement. With the developed MR polishing apparatus, the effects of trough speed, work and excitation gap width, particle concentration within the MR fluid and workpiece size on the material removal rate were systematically investigated. Final tests were performed on glass specimens to examine the polishing performance. The polishing area in the developed process was much larger than that of the conventional MR finishing process with a carrier wheel and ultra-smooth surface of 1 nm in R a was achieved. [ABSTRACT FROM AUTHOR]

Polycrystalline pyrochlore Lu 2 Ti 2 O 7 was irradiated with 200 keV He + ions at room temperature to fluences ranging from 2.0 × 10 15 to 2.0 × 10 17 He + /cm 2 . Irradiation-induced microstructural evolution was examined by grazing incidence X-ray diffraction and cross-sectional transmission electron microscopy. A micro-swelling (lattice expansion) induced by cation ion disordering was observed, which an obvious swelling was achieved at a fluence of 2.0 × 10 16 He + /cm 2 , and saturated at a fluence of 1.0 × 10 17 He + /cm 2 with cation ions fully disordered. Furthermore, during the irradiation process, the pristine pyrochlore phase was found to form by a fluence of 5.0 × 10 16 He + /cm 2 , corresponding to an average ballistic damage dose of ∼0.25 displacements per atom (dpa) for the near surface examined region. No amorphization was observed even to the highest fluence of 2.0 × 10 17 He + /cm 2 . The experimental observations are further discussed in the context of antisite formation in the pyrochlore Lu 2 Ti 2 O 7 . [ABSTRACT FROM AUTHOR]

Unfilled tetragonal tungsten bronze (TTB) structure Ba 4 LaTiNb 9 O 30 doped by Eu 3+ (BLTN: Eu 3+ x ) with different x have been prepared, and their structural, photoluminescence, dielectric, and ferroelectric properties are carefully investigated in this work. Bright red emission, originating from 5 D 0 → 7 F 1 and 5 D 0 → 7 F 2 transitions of Eu 3+ ions, has been observed by naked eyes at room temperature under near ultraviolet (NUV) light excitation. Optimized emission intensity is obtained when x = 1.00 for present unfilled TTB-type BLTN: Eu 3+ x samples. Furthermore, with increasing x , the dielectric and ferroelectric characteristics of the unfilled TTB-type BLTN: Eu 3+ x samples also display remarkable variation. When x ≥ 0.50 relaxor-like ferroelectric phase transitions are detected above room temperature, it is believed that unfilled TTB-type BLTN: Eu 3+ x = 1.00 involving bright photoluminescence and enhanced ferroelectric properties may act as a potentially multifunctional optical-electro material. [ABSTRACT FROM AUTHOR]

Ba 4 La 1− x Sm x TiNb 9 O 30 (BLTN: Sm 3+ x ) ceramics with different x have been synthesized. Their structural, photoluminescence, dielectric, and ferroelectric properties are investigated. By Rietveld structural refinement, BLTN: Eu 3+ x samples belong to the single unfilled tetragonal tungsten bronze (TTB) phase with space group P 4 bm . With deliberate introduction of Sm 3+ ions in the unfilled TTB-type structure, BLTN: Sm 3+ x samples simultaneously present bright reddish-orange emission and enhanced electrical properties. The reddish-orange emission, originating from 4 G 5/2 → 6 H J ( J =5/2, 7/2, and 9/2) transitions, has been observed by naked eyes under near ultraviolet radiation at room temperature. Furthermore, dielectric permittivity sharply changes with x and finally ferroelectric phase transitions above room temperature are realized in BLTN: Sm 3+ x under the stimulation of Sm 3+ ions. It is believed that BLTN: Sm 3+ x involving bright reddish-orange emission and enhanced electrical properties may act as a potentially multifunctional optical-electro material. [ABSTRACT FROM AUTHOR]

To clarify the role of carbon surface nature in the power generation of microbial fuel cell (MFC) based on carbon anode, three carbon felt samples, obtained by simple water cleaning (CCF), heating (HCF) and oxidation with ammonium persulfate (ACF), were characterized with SEM, BET, FTIR, cyclic voltammetry and acid titration, and their performances as anode of MFC were investigated with polarization curve measurement, chronoamperometry and chronopotentiometry. It is found that the power output of MFC depends on the morphology rather than the oxygen-containing group concentration of the carbon felt surface. CCF, HCF and ACF have their surface oxygen-containing groups of 1.52, 0.8 and 0.45 mM m −2 and specific surface areas of 0.33, 0.65 and 1.19 m 2 g −1 , but yield their maximal power densities of 606, 858 and 990 mW m −2 , respectively. This study suggests that intensive attention should be paid to the design of surface morphology in order to improve power generation of MFC. [ABSTRACT FROM AUTHOR]

Abstract: Filled tetragonal tungsten bronze (TTB) structure Sr4La2Ti4Nb6O30 co-doped by Er3+ and Yb3+ (SLTN: xEr3+–yYb3+) ceramics with different x and y were synthesized, and their crystal structure, upconversion photoluminescence (UC-PL), and dielectric permittivity were investigated for the first time. Under 980nm infrared (IR) excitation, bright single-band UC green (515–570nm) emission was observed for SLTN: xEr3+–yYb3+ (x=0.05, y=0), however, featured two-bands UC emission (515–570nm and 640–690nm) was confirmed for all SLTN: xEr3+–yYb3+ (x=0.05, y≠0) samples. Two-photon energy transfer process was proved through pumping laser power dependence of emission intensity measurement. It is believed that energy back transfer (EBT) process should be mainly responsible for the two-bands UC emission. In addition, the dielectric properties were also discussed for SLTN: xEr3+–yYb3+ system. [Copyright &y& Elsevier]

Abstract: In this report, we want to demonstrate that besides the conventional use for elemental analysis and depth profiling by ion beam analysis (IBA), particles generated through ion–solid interactions in IBA may find other novel and important applications. Specifically, we use Rutherford backscattered and nuclear reaction produced high energy proton particles to calibrate an energetic particle subsystem (called ZEP) of the Space and Atmospheric Burst Reporting System (SABRS) at Los Alamos National Laboratory (LANL). To simulate low radiation flux in the space, we have devised an experiment that uses an ultrathin (∼51.8nm) self-support gold foil to scatter a proton beam from a 3MV Tandem accelerator into the ZEP subsystem. Direct backscattering from the thin gold foil produces proton particles with tunable energies of 0.2–6.0MeV and desired counting rates of <10kHz. To extend the proton particle energy beyond the Tandem’s limit of 6MeV, a high Q-value nuclear reaction, 2D+ 3He→p+ 4He+18.352MeV, was used. This reaction allows us to obtain as high as 25.6MeV proton particles on our 3MV tandem accelerator, more than 4 times as high as the accelerator’s maximum proton beam energy, and has greatly extended our proton energy range for this calibration activity. Preliminary ZEP subsystem calibration results are presented. [Copyright &y& Elsevier]

Abstract: The effect of H isotope exchange and radiation damage on the retention of D in W was examined in the PISCES linear plasma device. W samples were treated with D plasma at low sample temperatures (473K), with a fluence of 1026 ions/m2 and ion energies of 150eV. Each sample was then exposed to varying doses of H plasma with similar sample temperature and plasma conditions to fluences ranging from 0 to 1026 ions/m2, to examine the effectiveness of isotope exchange as a means of tritium removal. The D(3He, p)4He nuclear reaction was used to measure D concentration profiles up to a depth of 7.7μm. Thermal desorption spectroscopy (TDS) was used to determine the D retained throughout the bulk of the sample. Isotope exchange allows for a unique study of atomic migration by separately examining the diffusion of implanted atoms from those bombarding the surface. D atoms are exchanged out of traps as a result of H plasma bombardment and diffuse until either falling into another trap or reaching the surface to recombine and escape. Radiation damage at levels of 0.01, 0.1, and 1 displacements per atom (dpa) was carried out before plasma exposure on some samples with 2MeV Cu ions as a surrogate for damage caused by fusion neutrons. The Cu ion damage was compared to damage induced by 6MeVW ions to see if there is an effect of Cu contamination on retention. We saw little difference in Cu versus W ion damage at low dpa, but at 1dpa, where Cu content reached 65appm, contamination seems to be significant. Retention measurements showed that ion damage has little effectiveness on isotope removal at these sample temperatures; however, there is evidence to suggest that the trapping mechanisms in W change as damage is increased. [Copyright &y& Elsevier]

Hard β-Ta phase is generally produced during Ta film deposition. While in some cases, soft α-Ta phase is preferred to ensure deformation capability. In this work, templated growth strategy by introducing Cr buffer layer is proposed to tailor the phase composition in Ta films. A broad spectrum of β-Ta/α-Ta ratio from 90% to 0% can be continuously and precisely achieved when the buffer layer thickness is correspondingly controlled from 0 to ∼90 nm. Hardness of the Ta films is well proportional to the β-Ta/α-Ta ratio. The underlying mechanism of phase tailoring is rationalized by demonstrating the thickness-dependent crystallization of buffer layer. [Display omitted]. [ABSTRACT FROM AUTHOR]

Abstract: Residual stress magnitudes and distributions in structural stainless steel built-up sections have been comprehensively investigated in this study. A total of 18 test specimens were fabricated from hot-rolled stainless steel plates by means of shielded metal arc welding (SMAW). Two grades of stainless steel were considered, namely the austenitic grade EN 1.4301 and the duplex grade EN 1.4462. Using the sectioning method, the test specimens were divided into strips. The residual stresses were then computed by multiplying the strains relieved during sectioning by the measured Young׳s moduli determined from tensile and compressive coupon tests. Residual stress distributions were obtained for 10 I-sections, four square hollow sections (SHS) and four rectangular hollow sections (RHS). Peak tensile residual stresses reached around 80% and 60% of the material 0.2% proof stress for grades EN 1.4301 and EN 1.4462, respectively. Based upon the test data, simplified predictive models for residual stress distributions in stainless steel built-up I-sections and box sections were developed. Following comparisons with other available residual stress test data, the applicability of the proposed models was also extended to other stainless steel alloys. The proposed residual stress patterns are suitable for inclusion in future analytical models and numerical simulations of stainless steel built-up sections. [Copyright &y& Elsevier]