JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2006
Kakarla Raghava Reddy
Abstract Composites of multiwall carbon nanotubes (MWCNTs) and sulfonated polyaniline (SPAN) were prepared through the oxidative polymerization of a mixture of aniline, 2,5-diaminobenzene sulfonic acid, and MWCNTs. Fe, Pd, or Fe,Pd alloy nanoparticles were embedded into the MWCNT,SPAN matrix by the reduction of Fe, Pd, or a mixture of Fe and Pd ions with , radiation. Sulfonic acid groups and the emeraldine form of backbone units in SPAN served as the source for the reduction of the metal ions in the presence of , radiation. The existence of metallic/alloy particles in the MWCNT,SPAN matrix was further ascertained through characterization by high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy, ultraviolet,visible spectroscopy, thermogravimetric analysis, and conductivity measurements. HRTEM pictures clearly revealed the existence of Fe, Pd, and Fe,Pd nanoparticles of various sizes in the MWCNT,SPAN matrices. There were changes in the electronic properties of the MWCNT,SPAN,M composites due to the interaction between the metal nanoparticles and MWCNT,SPAN. Metal-nanoparticle-loaded MWCNT,SPAN composites (MWCNT,SPAN,M; M = Fe, Pd, or Fe,Pd alloy) showed better thermal stability than the pristine polymers. The conductivity of the MWCNT,SPAN,M composites was approximately 1.5 S cm,1, which was much higher than that of SPAN (2.46 × 10,4 S cm,1). Metal/alloy-nanoparticle-embedded, MWCNT-based composite materials are expected to find applications in molecular electronics and other fields. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3355,3364, 2006 [source]

Equal Channel Angular Pressing of a Mg,3Al,1Zn Alloy with Back Pressure,

ADVANCED ENGINEERING MATERIALS, Issue 8 2010
Feng Kang
Abstract An extruded Mg,3Al,1Zn alloy bar is subjected to 1,4 passes equal channel angular pressing (ECAP) with or without 125,MPa backpressure via route Bc at 200,°C. Both strength and ductility are significantly increased after ECAP with backpressure; this is in strong contrast to the case of ECAP without backpressure, where significant improvement in ductility is accompanied by obvious decrease in yield strength from texture softening. Compared to ECAP without backpressure, much enhanced grain refinement, and the split of the dominant texture component of (0002) pole were observed with scatter intensity peaks in the case after ECAP with backpressure. This turns out to be resulted mainly from the activation of new slip system together with enhanced dynamic recrystallization under the effect of backpressure. The improvement of both strength and ductility in Mg,3Al,1Zn alloy through ECAP with back pressure provides a better approach to meet the engineering requests on comprehensive performance of this light alloy. [source]

Cost-Affordable Technique Involving Equal Channel Angular Pressing for the Manufacturing of Ultrafine Grained Sheets of an Al,Li,Mg,Sc Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 8 2010
Rustam Kaibyshev
A two-step process consisting of modified equal channel angular pressing (ECAP) and subsequent isothermal rolling (IR) was developed to produce thin sheets of aluminum alloys with ultra-fine grained (UFG) structure. Significant increase in the efficiency of ECAP was attained by using flat billets and a back pressure system. The incorporation of final IR into technologic route provides a reduced strain which is necessary to impose for the fabrication of thin sheets with UFG structure. In addition, it allows producing relatively "long billets." In order to demonstrate the feasibility of this technique an Al,5.1Mg,2.1Li,0.17Sc,0.08Zr (wt %) alloy was subjected to ECAP at 325,°C to a total strain of ,8 using processing route CX. The operation time of this processing did not exceed 15,min. Subsequent IR at the same temperature with a total reduction of 88% was applied to produce thin sheets with a 1.8,mm thickness and an average size of recrystallized grains of ,1.6,µm. These sheets exhibit extraordinary high superplastic ductilities. In addition, this material demonstrated almost isotropic mechanical behavior at room temperature. The maximum elongation-to-failure of ,2700% was attained at a temperature of 450,°C and an initial strain rate of 1.4,×,10,2 s,1. Thus it was demonstrated that the two-step processing consisting of ECAP with a back pressure followed by IR was a simple technique providing potential capability for the fabrication of superplastic sheets from an Al,Mg,Li,Sc alloy on a commercial scale. [source]

Phase Transformations During High-Pressure Torsion of Pure Zr and of a Zr-2.5%Nb Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 8 2010
Alexander P. Zhilyaev
Zirconium at normal conditions (room temperature and atmospheric pressure) has an HCP structure with lattice parameters a,=,3.2313,Å and c,=,5.1477,Å (,-phase). During loading under hydrostatic conditions in diamond anvil cells, a transition from the , -phase to an , -phase occurs at a pressure between 2 and 6 GPa and from , to , (bcc) at 30 GPa. It has been recently reported that the , to ,,+,, transformation might be induced by HPT processing. The resulting microstructures are stable at room temperature and atmospheric pressure. This paper explores the influence of previous processing steps and of composition in the feasibility of the HPT induced , to ,,+,, transformation. It will be shown that neither previous quenching nor high temperature HPT processing prevents the transformation from occurring during subsequent room temperature HPT. The addition of elements such as Nb also seems to favor the transformation. Understanding well the potential of HPT to stabilize high-pressure phases at normal conditions might be critical, as it will open a whole new range of applications for already existing materials. [source]

Mechanical Characterization of Particulate Aluminum Foams,Strain-Rate, Density and Matrix Alloy versus Adhesive Effects

ADVANCED ENGINEERING MATERIALS, Issue 7 2010
Dirk Lehmhus
Abstract The study evaluates mechanical properties of APM particulate aluminum foams built up from adhesively bonded Al foam spheres. Foams of matrix alloy AlSi10 are compared, with PM AlSi7 foams used as reference. The influence of density is studied both for quasi-static and dynamic compressive loading in a range from ,0.35 to 0.71,g,cm,3. The effect of varying the bonding agent is evaluated for a single density and both strain rate levels by replacing the standard, high-strength epoxy-based adhesive with a polyamide of greatly increased ductility. The result is a clear shift of fracture events to higher strain levels, as well as the introduction of a strain-rate dependency of strength. [source]

Microstructural Analysis of the Reinforced Al-Cu5mgti/Tib2 5,wt % Alloy for Investment Casting Applications,

ADVANCED ENGINEERING MATERIALS, Issue 6 2010
Pedro Egizabal
Abstract The paper describes the influence of 5,wt % titanium diboride (TiB2) particles on the microstructure of an Al-Cu alloy produced by plaster casting process. The elaboration route leads to a composite material with 1% of in situ TiB2 particles and 4% ex situ of TiB2 particles. The comparison of the reinforced alloy with the corresponding non-reinforced counterpart makes clear that the presence of TiB2 particles has a large influence in the observed microstructure. The presence of TiB2 particles decreases the grain sizes and the porosity level. It is also found that TiB2 particles play an important role in the precipitation events of Al2Cu precipitates that are formed during solidification at the TiB2/aluminum matrix interfaces. [source]

Influence of Heat Treatments on In Vitro Degradation Behavior of Mg-6Zn Alloy Studied by Electrochemical Measurements,

ADVANCED ENGINEERING MATERIALS, Issue 5 2010
Shaoxiang Zhang
The influence of heat treatment on the in vitro degradation of Mg-6Zn alloy is studied by electrochemical measurements. After solid-solution treatment, the microstructure of the Mg-6Zn becomes more homogeneous, along with an elevated charge-transfer resistance in SBF and a reduced corrosion current density. After ageing treatment, the discrete intermetallic ,-MgZn phase enhances the cathodic hydrogen evolution and impairs the corrosion resistance of the alloy. Galvanic cells are expected on ageing, but the ageing process makes the microstructure of the alloy homogeneous. Heat treatment alters the in vitro degradation behavior of Mg-6Zn alloy and is applicable in adjusting the biodegradation rate. [source]

Warm Laser Shock Peening Driven Nanostructures and Their Effects on Fatigue Performance in Aluminum Alloy 6160,

ADVANCED ENGINEERING MATERIALS, Issue 4 2010
Chang Ye
Warm laser shock peening is an innovative manufacturing process that integrates laser shock peening and dynamic aging to improve materials' fatigue performance. Compared to traditional laser shock peening (LSP), warm laser shock peening (WLSP) , i.e., LSP at elevated temperatures , provides better performance in many aspects. WLSP can induce nanoscale precipitation and high density dislocation arrangement, resulting in higher surface strength and lower surface roughness than LSP, which are both beneficial for fatigue life improvement. Due to pinning of the dislocation structure by nanoscale precipitates , so-called dislocation pinning effects , the relaxation of residual stress and surfaces dislocation arrangement is significantly reduced. In this study, AA6061 alloy is used to evaluate the WLSP process. It is found that the fatigue life improvements after WLSP are not only caused by large compressive residual stress and high density dislocations but also by the higher stability of the residual stresses and surface strength during cyclic loading. [source]

Physical and Numerical Simulation of Cold Rolling of an AlFeSi Alloy in Consideration of Static Recovery,

ADVANCED ENGINEERING MATERIALS, Issue 3 2010
Christoph Heering
The influence of static recovery on the yield stress of AA8079 was investigated in lab-scale cold rolling experiments. The yield stress of AA8079 in the cold rolling process is affected by static recovery, but the softening caused by static recovery is completely compensated in the subsequent cold rolling pass. Thus, the effect of static recovery on the yield stress of the final product is of minor importance. For the TPM, the kinetics of static recovery of the AlFeSi alloy AA8079 were determined for different temperatures and strain rates. The measured softening kinetics were then implemented in the physically based flow stress model 3IVM+. This flow stress model was extended with an empirical approach for static recovery to enable the through-process modeling of cold-rolled aluminum in consideration of static recovery. Future work will focus on physically based modeling of static recovery without using empirical approaches. [source]

Nanoindentation of a Pseudoelastic NiTiFe Shape Memory Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010
Janine Pfetzing-Micklich
Nanoindentation is a suitable tool for characterizing the local mechanical properties of shape memory alloys (SMA) and to study their pseudoelastic behavior. There is a special interest in indenting with different indenter tips (as not all tips are associated with strain states that predominantly induce the martensitic transformation) and in indenting at different temperatures, where different phases are present. In this study, we perform nanoindentation on a ternary NiTiFe SMA with different indenter tips and at various testing temperatures. For nanoindentation with spherical tips, load,displacement hystereses clearly indicate pseudoelastic behavior, whereas indentation with Berkovich tips results in more pronounced plastic deformation. Testing at different temperatures is associated with different volume fractions of austenite, martensite, and R-phase. The corresponding nanoindentation responses differ considerably in terms of pseudoelastic behavior. Best pseudoelastic recovery is found at testing temperatures close to the R-phase start temperature, even though this temperature is below the austenite finish temperature, which is a well-known lower temperature bound for full recovery in macroscopic tests. Our results are discussed considering micromechanical aspects and the interaction between stress-induced phase transformation and dislocation plasticity. [source]

Formation and Stability of Near Convoluted Structure Obtained in the Ti,46Al,8Ta Alloy Via Air Quenching and Ageing,

ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010
Valery Imayev
Abstract Microstructure evolution after air quenching and variable ageing treatment has been investigated in small-sized ingot bars of the Ti,46Al,8Ta alloy. It was found that air quenching and subsequent ageing at 1200,1260,°C led to the formation of a homogeneous refined near convoluted microstructure. To increase the stability of the near convoluted structure, very slow cooling after high-temperature ageing and final long-term ageing at around 900,°C can be recommended. [source]

Microstructure and Texture Formation During Near Conventional Forging of an Intermetallic Ti,45Al,5Nb Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 12 2009
Andreas Stark
Abstract Texture formation was studied in an intermetallic Ti-45at%Al-5at%Nb alloy after uniaxial compression and near conventional forging. Depending on the deformation conditions the texture of the , -TiAl phase is formed by pure deformation components, components related to dynamic recrystallization, or transformation components. This changing corresponds with microstructural observations. The ,2 -Ti3Al and the , -Ti(Al) phase show a similar texture as it is known for Ti and Ti-base alloys after compressive deformation at elevated temperatures. In contrast to the , texture, no significant change of the ,/,2 texture was observed in the temperature range between 800,°C and just below the , -transus temperature (T,,=,1295,°C). [source]

Environmental Behavior and Stress Corrosion Characteristics of Nano/Sub-Micron E950 Aluminum Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 11 2009
Eli Aghion
The corrosion performance and stress corrosion resistance of E950 Aluminum alloy with nano/sub-micron structure were evaluated in 3.5% NaCl solution. The results obtained indicated that the corrosion and stress corrosion resistance of E950 alloy were relatively reduced compared to that of the conventional coarse-grained alloy (Al,4.65%Mg). In particular, the inherently improved ultimate tensile strength of E950 alloy was significantly decreased under stress corrosion conditions. [source]

Tribological Studies of a Zr-Based Glass-Forming Alloy with Different States,

ADVANCED ENGINEERING MATERIALS, Issue 11 2009
Feng Jiang
Abstract The tribological characteristics of a glass-forming alloy, Zr52.5Cu17.9Ni14.6Al10.0Ti5.0, in atomic percent (at.%, Vit 105), with different microstructural states have been investigated. Friction and wear studies were conducted using a ball-on-flat reciprocating sliding apparatus against an AISI E52100 bearing steel under dry condition. The observed wear resistance in an ascending order is: the deformed, creep-tested, and as-cast states. Wear analyses suggested that the wear processes of glass-forming alloys involved abrasion, adhesion, and oxidation. The differences in hardness, free volume, and brittleness in different states significantly affected the friction and wear behaviors of the glass-forming alloys. [source]

In Situ Characterization of a Nb and Mo Containing , -TiAl Based Alloy Using Neutron Diffraction and High-Temperature Microscopy,

ADVANCED ENGINEERING MATERIALS, Issue 11 2009
Ian J. Watson
Abstract In recent times, novel titanium aluminides containing the bcc , -phase at high temperatures are being developed for improved hot-working capabilities, however, predictions of the phase diagrams are merely uncertain. Here we present in-situ neutron studies, which are particularly sensitive to the atomic disorder in the ordered phases. Complementary laser scanning confocal microscopy is employed for in-situ microstructural investigations. [source]

In Situ Observation of Dynamic Recrystallization in the Bulk of Zirconium Alloy (Adv. Eng.

ADVANCED ENGINEERING MATERIALS, Issue 8 2009
Mater.
The cover shows the in-situ diffraction setup. A fine synchrotron beam transmits the sample situated in a (heated) load frame and scatters into Debye-Scherrer cones. Large crystallites map onto spots onto the 2D detector rather than continuous rings. In the background, the intensity distribution of one selected reflection - here beta-Zr 110 - is plotted in color scale as a function of azimuthal angle (horizontal axis) and time (vertical axis) revealing the different states during thermo-mechanical processing. More details can be found in the article by K.-D. Liss on page 637. [source]

In Situ Observation of Dynamic Recrystallization in the Bulk of Zirconium Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 8 2009
Klaus-Dieter Liss
Dynamic recrystallization and related effects have been followed in situ and in real time while a metal undergoes rapid thermo-mechanical processing. Statistics and orientation correlations of embedded/bulk material grains were deduced from two-dimensional X-ray diffraction patterns and give deep insight into the formation of the microstructure. Applications are relevant in materials design, simulation, and in geological systems. [source]

Solid Solution or Intermetallics in a High-Entropy Alloy

ADVANCED ENGINEERING MATERIALS, Issue 8 2009
Yan Ping Wang
The modulated structure of the AlCrFeCoNiCu high-entropy alloy consists of NiAl intermetallics (,,) and a (,-Fe, Cr) solid solution (,). The formation of the NiAl intermetallics greatly affects the strengths and magnetic properties of the AlxCrFeCoNiCu alloys. Evidently, the AlCrFeCoNiCu alloy cannot be treated as a solid-solution alloy. [source]

Activation Mechanism and Infiltration Kinetic for Pressureless Melt Infiltration of Ti Activated Al2O3 Preforms by High Melting Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 8 2009
Srdan Vasi
The infiltration mechanism of X3CrNi13-4 in titanium activated porous alumina preforms has been studied. Investigations revealed isolated steel-covered titanium particles beyond the infiltration front. The only transport path possible for the steel to form such wetted islands is through the gas phase. Supersaturation due to the mixing of the steel gas phase with the titanium rich gas phase over the activator particle surfaces is proposed as condensation mechanism. Progressive condensation leads to the formation of a melt network, which serves as pathway for the original steel melt to infiltrate the preforms and to fill the remaining pore space in the non-wetting X3CrNi13-4/Ti-Al2O3 sytem. [source]

The Coupling Effect of Small Nanocrystals and Free Volume on the Ductility of Cu46Zr47Al7 Bulk Metallic Glass Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 5 2009
Feng Jiang
Cu46Zr47Al7 bulk metallic glass (BMG) and its composite containing small in situ precipitated nanocrystals were prepared through copper mold casting. Different free volume states of these Cu46Zr47Al7 alloys were obtained through thermal treatment such as annealing and quenching. Three-point bending tests for these alloys were undertaken to evaluate their plastic deformation ability. Free volume changes were measured indirectly but quantitatively with differential scanning calorimetry (DSC) method. The results show that, the ductility of Cu46Zr47Al7 alloys is closely related with the free volume states and the ductility of thermally embrittled Cu46Zr47Al7 alloys samples can be partially recovered by restoring free volume through quenching process. The presence of small nanocrystals is more efficient than free volume to enhance the ductility. However, only with the concurrence of the small nanocrystals and the free volume, the Cu46Zr47Al7 BMG alloys will present excellent ductility. [source]

Hot Workability, Microstructural Control and Rate-Controlling Mechanisms in Cast-Homogenized AZ31 Magnesium Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 3 2009
Yellapregada Venkata Rama Krishna Prasad
Optimum conditions for microstructural control in industrial hot working of cast and homogenized AZ31 magnesium alloys are evaluated by using a processing map. The recommended window for bulk metal working of this alloy is the domain in the temperature range 300,450,°C and strain rate range 1,10,s,1, and the optimum processing parameters are 400,°C and 10,s,1, where grain-boundary self diffusion is the rate-controlling mechanism. [source]

Effects of Zirconium Additions on the Microstructure of As-Cast and Aged AZ91 Magnesium Alloy

ADVANCED ENGINEERING MATERIALS, Issue 3 2009
Farhoud Kabirian
The effects of Zr addition on the microstructure of AZ91 alloy were investigated under as-cast and isothermally aged conditions. The microstructures contained a eutectic , -Mg17Al12 phase together with fine Al,Zr intermetallic compounds. These intermetallic compounds inhibited grain growth during the 420,°C isothermal aging of Zr-containing alloys. Microstructural changes caused by Zr additions were most probably due to the consumption of Al by Zr, and redistribution of Al during solidification of dendrites. [source]

Enhanced Ductility of Dendrite-Ultrafine Eutectic Composite Fe3B Alloy Prepared by a Self-Propagating High-Temperature Synthesis,

ADVANCED ENGINEERING MATERIALS, Issue 3 2009
Licai Fu
The bulk dendrite-ultrafine eutectic composite Fe3B alloy was prepared by a self-propagating high-temperature synthesis. This technique is convenient, low cost, and capable of being scaled up for processing bulk nano/ultrafine-structured materials. The Fe3B alloy is composed of a micrometer-sized dendrite dispersed in an ultrafine laminar eutectic matrix and exhibits both high strength and large ductility in compressive tests. [source]

A Novel Fe-Mn-Si Shape Memory Alloy With Improved Shape Recovery Properties by VC Precipitation

ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009
Zhizhong Dong
In this work, a nominally new Fe-Mn-Si based shape memory alloy with a small amount of VC was designed. After an optimized thermo-mechanical treatment, a shape recovery of more than 90% after an elongation of 4% could be achieved when the alloys were heated up to 225°C. In addition, high recovery stresses of up to 380 MPa could be obtained after heating to 225°C, whereas 330 MPa were obtained after heating to 160°C. [source]

Formation of a Multiphase Gradient Structure in a Zr,Cu,Ni,Al,O Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 4 2008
F. Qiu
The phase formation upon rapid cooling by copper mould casting of a Zr-Cu-Al-Ni alloy with two different oxygen contents is reported. The nominally oxygen-free alloy produces a glassy phase, whereas the presence of 0.56 at.% oxygen results in crystallization. The crystalline phase selection is governed by the cooling rate. The microstructure and mechanical properties as well as the correlation between them in the oxygen-containing alloy were investigated. [source]

Mechanical Properties and Environmental Behavior of a Magnesium Alloy with a Nano-/Sub-Micron Structure

ADVANCED ENGINEERING MATERIALS, Issue 9 2007
E. Aghion
Abstract Newly developed magnesium alloys with a consolidated nano/sub-micron structure and substantially higher specific strength may be considered as an interesting candidate for super-light high-strength applications. Consolidated nano/sub-micron structure applies to alloys with a combined microstructure of nano-crystalline and sub-micron grains. The aim of the present study was to explore the mechanical and environmental behavior of a consolidated nano/sub-micron magnesium alloy with the composition of AZ31. This was required in order to evaluate the applicability of this new structured alloy for practical applications. Although the nano/sub-micron structured alloy has more than twice the hardness and strength of the conventional alloy, its ductility and corrosion resistance were significantly lower. In addition, its stress corrosion characteristics were inferior. The significant limitation of the nano-structured alloy, in terms of ductility and corrosion performance, restricts its potential use as a structural material for practical applications. [source]

Analysis of Superplastic Deformation of AZ31 Magnesium Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 9 2007
K. Abu-Farha
AZ31 is a magnesium alloy possessing good mechanical properties, which makes it particularly attractive for automotive applications. Yet, in order to advance the utilization of this alloy, a broad database of its superplastic behavior is needed. This work presents the results of a comprehensive study on the elevated temperature superplastic behavior of the AZ31 magnesium alloy. Flow stress, fracture strain and strain sensitivity index maps were constructed over a wide range of strain rates, covering temperatures between 325 and 450 °C. [source]

Hot Deformation Mechanisms and Microstructural Control in High-Temperature Extruded AZ31 Magnesium Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 7 2007

A Processing map has been developed for Magnesium alloy AZ31 extruded at 450,°C which revealed that the extruded rods may be further processed into components industrially at 400,°C and at a strain rate of 10,s,1. If processed at lower strain rates in the vicinity of 0.1,s,1, unusual grain size variations with temperature and strain rate are observed, suggesting that grain size control will be difficult. [source]

Nanocrystallized Al92Sm8 Amorphous Alloy Investigated by High-Resolution Microscopy and 3D Atom-Probe Analysis

ADVANCED ENGINEERING MATERIALS, Issue 3 2007
T. Gloriant
A partially nanocrystallized amorphous Al92Sm8 (at.%) alloy was obtained directly by rapid solidification (one-step method). Because of the significant retained plasticity of the as-quenched alloy, the nanostructure and the atomic species distribution within the nanocomposite material could be characterized by field-ion microscopy (FIM) and by three-dimensional atom-probe analysis (3DAP). [source]

Mechanical Properties and Corrosion Resistance of a Novel Ni-Cr-Mo Alloy,

ADVANCED ENGINEERING MATERIALS, Issue 1-2 2007
P. Huang
A new Ni-23Cr-18Mo (wt.%) alloy, designated as Nistelle Super C, was developed recently at Deloro Stellite Inc. for high corrosion resistance applications. Microstructure and phase transformation behaviour of the alloy were studied using SEM and DSC techniques, respectively. Mechanical properties such as stress - strain relation of the alloy and load , depth relation of individual phases of the alloy were determined under uniaxial tension and under nano indentation, respectively. Corrosion resistance of the alloy in oxidizing and reducing acids was evaluated in accordance with ASTM standard test designation G31-72. [source]