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Microstructural characteristics and mechanical properties of the ductile iron in three heat treatment processes (normalizing, quenching + high‐temperature tempering and isothermal quenching) were investigated in this paper. The pearlite and ferrite with large‐sized spherical graphites can be obtained in the normalized sample, and the spherical graphites with relatively large size can still be observed in the mechanical mixture of tempered martensite and acicular ferrite for the quenched‐tempered sample. Meanwhile, the lower bainite accompanied with the relatively fine spherical graphites are existed in the isothermal‐quenched sample. The difference of tensile strength is mainly caused by the phase composition, distribution and size of the spherical graphites and the effect of the solid solution strengthening. The weaker degree of the debonding damage, higher proportion of high‐angle grain boundaries will improve the impact toughness of the ductile iron. In a word, the optimum combination of strength and toughness is acquired by using isothermal quenching, and the tensile strength and impact toughness are ~1350 MPa and ~10.62 J, respectively. [ABSTRACT FROM AUTHOR]

Biodegradable Zn‐0.45Li alloys with high strength and ductility were successfully fabricated by hot extrusion and multi‐pass drawing to obtain ultrafine‐grained microstructures with a secondary phase of fine LiZn4 participates. The mechanical properties, degradation behavior and cytocompatibility of the alloys were subsequently investigated. Results showed that grain refinement could be achieved in the alloys after hot extrusion and multi‐pass drawing. The yield strength, ultimate tensile strength, and elongation to failure of the ultrafine‐grained Zn‐0.45Li alloys reached 416 MPa, 567 MPa and 55.4 %, respectively. Enhancements in both strength and elongation could be attributed to interactions between LiZn4 and matrix dislocations, the pinning effect of LiZn4 on grain boundaries, and grain refinement. Immersion tests and MTT cytotoxicity assay indicated that the Zn‐0.45Li alloys have a corrosion rate and cytocompatibility similar to the values reported for biomedical implants. [ABSTRACT FROM AUTHOR]

We prepared V-doped Bi6Fe2Ti3O18 thin films on Pt/Ti/SiO2/Si (100) substrates by using a chemical solution deposition route and investigated the doping effect on the microstructure, dielectric, leakage, and ferroelectric properties of Bi6Fe2Ti3O18 thin films. The Bi5.97Fe2Ti2.91V0.09O18 thin film exhibits improved dielectric properties, leakage current, and ferroelectric properties. The incorporation of vanadium resulted in a substantially enhanced remnant polarization (2Pr) over 30μC/cm2 in Bi5.97Fe2Ti2.91V0.09O18 thin film compared with 10μC/cm2 in Bi6Fe2Ti3O18 thin film. It is demonstrated that the improved properties may stem from the improvement of crystallinity of the films with the contribution of suppressed oxygen vacancies and decreased mobility of oxygen vacancies caused by the V-doping. The results will provide a guidance to optimize the ferroelectric properties in Bi6Fe2Ti3O18 thin films by chemical solution deposition, which is important to further explore single-phase multiferroics in the n=5 Aurivillius thin films. [ABSTRACT FROM AUTHOR]

We investigate the structural, magnetic, and electrical properties of charge-spin co-doped Ba1-x-yLax+yTi1-xMxO3 (M = Cr, Fe, and Co). For Ba1-x-yLax+yTi1-xCrxO3, carrier doping induces short-range ferromagnetism, and we find a large negative magnetoresistance in these compounds. However, for Ba1-x-yLax+yTi1-xMxO3 (M = Fe and Co), the magnetism does not seem to couple with the charge carriers. The transport properties of Ba1-x-yLax+yTi1-xCrxO3 can be described by a three-dimensional variable-range-hopping model that implies itinerant charge carriers, whereas almost all the samples of Ba1-x-yLax+yTi1-xMxO3 (M = Fe and Co) exhibit high resistivity. It is known that only the itinerant charge carriers can enhance the coupling of two isolated magnetic ions. Therefore, there is almost no long-range ferromagnetism in the studied system. [ABSTRACT FROM AUTHOR]

The effect of composition, casting, and heat treatment on the eutectic phase morphology of an Al–Zn–Ni–Mg–Cu casting aluminum alloy was studied. The effect of the eutectic phase on the microstructure and mechanical properties was evaluated. The strength of a casting aluminum alloy under squeeze casting is higher than that of sand and permanent-mold castings. The maximum tensile strength and elongation reached 586 MPa and 3.5%, respectively, which contributed to the ageing strengthening effect of η(MgZn2) phase and the dispersion strengthening effect of an Al3Ni phase. The finer the Al3Ni phase, the better the strengthening effect. A Fe content should be limited, a Ni content is to be less than the eutectic point composition, Zn, Mg, and Cu contents are optimized. The aluminum alloy should be treated by the two-stage solution treatment, the first stage temperature does not exceed 473°C. [ABSTRACT FROM AUTHOR]

We investigate the effect of high magnetic-field annealing on the microstructural, ferroelectric, and magnetic properties of Bi6Fe1.4Co0.6Ti3O18 thin films. The magnetic field can lower the energy barrier for nucleation and improve the grain connectivity. The application of magnetic field of 6T parallel to the film plane can substantially enhance the remnant polarization Pr from 18.1 to 29 μC/cm² as a result of the variation in grain size and growth orientation caused by magnetic field annealing. Moreover, the remnant magnetization Mr is substantially improved from 2.48 to 4.56 emu/cm³ arising from the enhanced exchange coupling due to the better grain connectivity. These results demonstrate that high magnetic-field annealing is an effective way to optimize multiferroic properties of the Aurivillius compounds. [ABSTRACT FROM AUTHOR]

The influence of homogenisation annealing process on microstrucure of 7085 Al alloy has been investigated by optical microscopy(OM), scanning electron microscopy combined with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction(XRD), and differential scanning calorimetry (DSC). The results show a large amount of skeletal Mg(Zn, Al, Cu)2 phase and AlZnMgCu phase distributed as eutectic microstructure on crystal boundaries, and some impurity phase of triangle or square Al18Mg3Cr2 in the interior of grain in as-cast 7085Al alloys. In combination with DSC and OM observation, the temperature of homogenisation annealing is determined lower than 473°C. With increasing temperature of homogenising annealing, the woven crystal microstructure on the grain boundary and part lager block second phase in interior of grain decreases, and grain boundary turns to be discontinuous. 7085Al alloys are treated by homogenising annealing of 470°C/24 h, grain boundary turns to be discontinuous, uniform and fine precipitation phase arises, and woven eutectic microstructure and lager block second phase disappear. The optimised homogenising annealing is 470°C/24 h in the study. [ABSTRACT FROM AUTHOR]

The coloured ceramic coating was prepared by using micro-arc oxidation technology on aluminium. CuSO4 was used as the colourant to produce the brown micro-arc oxidation coating. The effects of the applied current density on characteristics and properties of the micro-arc oxidation coating were studied. The results showed that there were significant changes on colour, surface morphology, thickness and corrosion resistance of the micro-arc oxidation coating when the current density increased: The colour deepened, and the pore size increased. In addition, the thickness of the micro-arc oxidation coating rose, and the roughness of the coating increased gradually. But the corrosion resistance of the micro-arc oxidation coating increased when the current density increased from 4 to 7 A dm−2, and then it dropped when the current density increased from 7 to 8 A dm−2. [ABSTRACT FROM AUTHOR]

The polytetrafluoroethylene (PTFE) composites filled with CaF2 gas are ablated by laser beam instead of arc and the microstructure and the contents of the main elements on the ablated surfaces of PTFE composites are analysed through scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The mechanism of the resistance to laser ablation influenced by CaF2 is studied. The results indicate that it exists an optimum content of CaF2 at which PTFE acquires a relatively high resistance to laser radiation; the optimum content of CaF2 could improve the reflectivity, regulate absorption of laser energy and improve PTFE composites resistance to laser ablation. [ABSTRACT FROM AUTHOR]

Dielectric strength and energy storage density in BaLnTiO (Ln = La, Sm) low-loss dielectric ceramics have been investigated together with their composition and microstructure dependences. The dielectric strength increases with increasing x at first, reaches the maximum around x = 2/3 and turns to decrease for x = 3/4, except the composition x = 3/4 for BaSmTiO, while the energy storage density decreases generally with increasing x. The maximum energy storage density is 0.38 J/cm under an electric field of 26 MV/m for x = 1/4 in BaLaTiO. The highest dielectric strength and energy storage density are obtained in the present ceramics with the maximum bulk density and the minimum grain size. Compared with the ferroelectric materials, very low dielectric loss combined with the excellent temperature stability provide the essential advantages for the energy storage applications. [ABSTRACT FROM AUTHOR]

Porous titanium with appropriate surface treatments can be osteoinductive. To investigate the effect of surface treatments of porous titanium on the attachment and differentiation of mesenchymal stem cells (MSCs), two kinds of surface microstructured porous titaniums, HO/TaCl treated one (HTPT), and HO/TaCl and subsequent simulated body fluid (SBF) treated one (STPT) were fabricated, and non-treated one (NTPT) was used as control. The morphology, specific surface area (SSA), pore distribution and mechanical strength of these materials were characterized respectively, and the results showed that HO/TaCl treatment led to a significant increase in both SSA and micropores of HTPT, and the further SBF immersion resulted in the formation of a layer of bone-like apatite on the surface of STPT. Although the surface treatments had a little negative impact on the compressive strength and elasticity modulus of porous titanium, the mechanical strength of HTPT or STPT was enough for the bone defect repair of the load-bearing sites. The protein adsorption and cell adhesion experiments confirmed that the microstructured surface notably enhanced porous titanium's protein binding capacity and promoted MSCs adhesion on the surface. More importantly, cell differentiation experiments proved that the microstructured surface evidently elevated the osteoblastic gene expressions of MSCs compared to NTPT. The enhanced biological effect by the surface treatments was more robust on STPT. Therefore, our results suggest that the microstructured surface has great potential for promoting MSCs differentiation towards osteoblasts, giving excellent support for the osteoinduction of porous titanium with appropriate surface treatments. [ABSTRACT FROM AUTHOR]

Severely localized deformation within shear bands can occur much more easily in a metal with nanoscale microstructures, such as nanograined and nanolayered materials. Based on atomic-scale observations, here we show that such locally large deformation (the continuous thinning of the layers) within the indentation-induced shear bands of the Cu/Au nanolayers is essentially attributed to the large shear stress component along the interface, which can refresh the capability of the interface to absorb incoming dislocations through unlocking the product of the dislocation-interface reaction. The results have implications for understanding the interface-mediated mechanisms of plastic deformation and for the engineering application of severe plastic deformation processing of metals at nanoscales. [ABSTRACT FROM AUTHOR]

Extraordinary thermal emission properties of the metallic surface microstructures induced by femtosecond lasers are investigated in both experiment and theory. Within the spectral range of 4-17 μm, the measured maximum thermal emissivities at different temperatures enhance significantly to about 100%. Especially for the coral-like surface structure, the improved thermal emission behaviors can extend largely over the whole spectrum rather than happening at some distinctive wavelengths. Moreover, the enhancement factor of the thermal emissivity is observed to depend on the wavelength and the idiographic morphology of the microstructures. This phenomenon can be understood well by equivalent recognizing the SPP field coupling assisted transmission of blackbody radiation through the microstructured interfaces, and the finite-difference time-domain simulations elucidate the underlying physical pictures. [ABSTRACT FROM AUTHOR]

Abstract: Intermetallic NiAl has the potential to be used for elevated temperature applications. To date different ignition techniques have been utilized to synthesize NiAl and produce coatings. Self-propagating high-temperature synthesis (SHS) has been developed as a relatively simple route to obtain intermetallics. This paper considers using induction heating to preheat and ignite the synthesis directly and investigates the effect of processing parameters on the phase transformation, microstructures and properties of Ni/Al compacts synthesized by SHS. The results show that single phase NiAl can be produced by induction heating whilst processing parameters such as heating rates and green densities have a significant effect on the properties and structures of sintered products. [Copyright &y& Elsevier]

The intrinsically core/shell structured La0.6Sr0.4MnO3 nanoparticles with amorphous shells and ferromagnetic cores have been prepared. The magnetic, dielectric and microwave absorption properties are investigated in the frequency range from 1 to 12 GHz. An optimal reflection loss of −41.1 dB is reached at 8.2 GHz with a matching thickness of 2.2 mm, the bandwidth with a reflection loss less than −10 dB is obtained in the 5.5–11.3 GHz range for absorber thicknesses of 1.5–2.5 mm. The excellent microwave absorption properties are a consequence of the better electromagnetic matching due to the existence of the protective amorphous shells, the ferromagnetic cores, as well as the particular core/shell microstructure. As a result, the La0.6Sr0.4MnO3 nanoparticles with amorphous shells and ferromagnetic cores may become attractive candidates for the new types of electromagnetic wave absorption materials. [ABSTRACT FROM AUTHOR]

Abstract: The effects of microstructure and temperature on the fatigue behavior of a commercial Al–Si–Cu alloy used in automotive engine components were investigated for lifetimes as long as 109 cycles using ultrasonic fatigue instrumentation operating at 20kHz. The primary finding of this study is that the influence of microstructure on the cyclic properties is greater than the influence of the testing temperature. Fractographic studies indicated that most fatigue cracks initiate from microshrinkage pores located at or very near to the specimen surface, while a much smaller number of cracks initiate from twin boundaries. Increasing test temperature resulted in a modest decrease in endurance limit by about 12% from 20 to 150°C, while a significant decrease in endurance limit by about 23% was observed from 150 to 250°C at high number of cycles. Using fatigue data developed in this study, a statistical model, the random fatigue-limit model (RFL), was evaluated for its utility in estimating fatigue behavior in the gigacycle regime. [Copyright &y& Elsevier]

We report a comparative study of the microstructure of compositionally graded (Ba1-xSrx)TiO3 (BST) films with two compositionally graded directions, up and down, with respect to the substrate, which were deposited epitaxially on (La,Sr)CoO3 (LSCO)-covered MgO(100) single-crystal substrates by pulsed laser deposition. Cross-sectional transmission electron microscopy (TEM) images and electron diffraction show that the graded films grow epitaxially with their (100) plane parallel to the (100) surface of the MgO single-crystal substrate, and with an in-plane orientation relationship of 〈001〉BST//〈001〉LSCO//〈001〉MgO. The crystalline quality and surface morphology of the graded films are closely related to the direction of the compositional gradient built into the graded films. Down-graded films (starting with a BaTiO3 layer at the film/substrate interface) have a much better crystalline quality and a smoother surface than the up-graded films (starting with a (Ba0.75Sr0.25)TiO3 layer at the film/substrate interface). Obviously, the BaTiO3 bottom layer in the down-graded film acts not only as a part of the graded film but also as an excellent seeding layer to enhance the crystallization of the subsequent film layers, resulting in a high crystalline quality of the down-graded film and an enhanced dielectric behavior. Planar (high-resolution) TEM images also demonstrate that down-graded films have a larger, and more uniform, grain size than up-graded films, and that the latter contain voids. [ABSTRACT FROM AUTHOR]

The morphology and microstructure of all-epitaxial (Bi,La)4Ti3O12/Pb(Zr0.4Ti0.6)O3/(Bi,La)4Ti3O12 (BLT/PZT/BLT) tri-layered ferroelectric films, grown on (011)-oriented SrTiO3 (STO) substrates by pulsed laser deposition, are investigated by transmission electron microscopy (TEM). X-ray diffraction and electron diffraction patterns demonstrate that the epitaxial relationship between BLT, PZT and STO can be described as;. Cross-sectional TEM images show that the growth rate of BLT is nearly two times that for PZT at the same growth conditions, and 90° ferroelectric domain boundaries lying on {110} planes are observed in the PZT layer. The 90° ferroelectric domains in the PZT layer extend up to 600 nm in length. Long domains penetrate into the neighboring columnar grain through the columnar grain boundary, whereas others are nucleating at the columnar grain boundaries. The roughness of the PZT/BLT interfaces appears to depend on the viewing direction, i.e., it is different for different azimuthal directions. Planar TEM investigations show that the grains in the top BLT layer have a rod-like morphology, preferentially growing along the [110]BLT direction. The grain width is rather constant at about 90 nm, whereas the length of the grains varies from 150 to 625 nm. These morphological details point to the important role the crystal anisotropy of BLT plays for the growth and structure of the tri-layered films. [ABSTRACT FROM AUTHOR]

Compositionally graded (Ba1-xSrx)TiO3 (BST) thin films, with x decreasing from 0.25 to 0.0, were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by pulsed-laser ablation at 600 °C and under ambient oxygen pressures ranging from 50 to 400 mTorr. The influence of the ambient gas pressure on the preferred orientation, microstructures, and dielectric properties of compositionally graded BST films was investigated by X-ray diffraction, scanning electron microscopy, and dielectric frequency spectra, respectively. As the ambient oxygen pressure was increased, the preferred orientation evolved in the order: (100)+(110)?(110)+(111)? random orientation, and the surface roughness of the graded BST films also increased. The graded BST films deposited at high ambient oxygen pressures (300~400 mTorr) exhibited a grainy structure with polycrystalline grains throughout the film thickness, whereas the graded films deposited at low ambient oxygen pressures (50~200 mTorr) possessed a columnar structure. The evolution of the microstructure was ascribed to the different physical and chemical properties of the species that were incident onto the substrates at the various oxygen pressures. The dielectric properties of the graded BST films were dependent upon the ambient oxygen pressures. The graded BST films deposited at 200 mTorr exhibited the highest dielectric constant. [ABSTRACT FROM AUTHOR]

Rutile TiO2 nanorods have been successfully prepared by a sonochemical method. The microstructures of TiO2 nanorods were investigated in detail by transmission electron microscopy (TEM), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HREM). Probable mechanisms for the sonochemical formation of TiO2 nanorods are proposed. [ABSTRACT FROM AUTHOR]

The significance and theoretical basis of the strengthening process of electrodeposited Co–W–Ti–Al2O3 composite coatings and nitrocarburisation are briefly explained. The conditions of the composite process and the characteristics of the composite heat treated coatings are studied in detail. Co–W–Ti–Al2 O3 composite coatings with good characteristics are obtained on steel when the appropriate complex agent and additives are selected and the conditions of the composite electrodeposition process are controlled. The hardness and wear resistance of the composite coatings after nitrocarburising are much better than those of the composite without nitrocarburisation. The hardness of the nitrocarburised Co–W–Ti–Al 2O3 composite is found to decrease gradually from the surface into the internal layer. X-ray diffraction shows that the diffused coating contains a solid solution of cobalt, titanium carbide, titanium nitride, tungsten carbide, tungsten nitride and alumina, together with a little r-(FeCo), when the Co–W–Ti–Al2O3 composite coating is nitrocarburised. SE/514 [ABSTRACT FROM AUTHOR]

The structure, hardness and wear resistance of RE - Ni -Mo - P- B4C- PTFE composite coatings were studied using XRD, SEM, an MM2000 abrasion tester and an HX-1 microhardness tester. Results show that the structure of the composite coatings experiences a transformation process from amorphous to mixture and then to crystalline as the heat treatment temperature rises. The crystal particles of the coatings become increasingly fine with the addition of B4C, B4C+PTFE and B4C+RE. The hardness and wear resistance of RE-Ni -Mo- P -B4C- PTFE composite are raised with increasing heat treatment temperature, reaching peak values at 400°C and 300°C, respectively. The wear resistance of the composite coatings is greatly superior to that of other traditional coatings. [ABSTRACT FROM AUTHOR]

Compositionally graded (Ba[sub 1-x] Sr[sub x] )TiO[sub 3] (BST) (x:0.0∼0.25) thin films were grown on Pt (111)/TiO[sub 2] /SiO[sub 2] /Si (100) substrates using layer-by-layer pulsed laser deposition in the temperature range 550–650 °C. Both downgraded (Ba/Sr ratio varying from 100/0 at the bottom surface to 75/25 at the top surface) and upgraded (Ba/Sr ratio varying from 75/25 at the bottom surface to 100/0 at the top surface) BST films were prepared. Their microstructures were systematically studied by X-ray diffractometry and scanning electron microscopy. A grain morphology transition from large ‘rosettes’ (>0.30 μm) to small compact grains (70–110 nm) was observed in the downgraded BST films as the deposition temperature was increased from 550 to 650 °C. No such grain morphology transition was detected in the upgraded BST films. Dielectric measurements with metal electrodes revealed an enhanced dielectric behavior in the downgraded films. This enhancement is mainly attributed to the large compressive stress field built up near the interface between the downgraded film and substrate. Furthermore, the BaTiO[sub 3] layer in the downgraded BST films not only serves as a bottom layer but also as an excellent seeding layer for enhancing the crystallization of the subsequent film layers in the downgraded films. [ABSTRACT FROM AUTHOR]

The deposition of poly-crystalline diamond (poly-C) in narrow silicon channels has been accomplished, resulting in narrow freestanding diamond channels. The channels were seeded using a combination of ultrasonic stirring and electrophoresis in a diamond/isopropanol solution. These channels have openings with thicknesses as low as ∼2 μm. The use of such diamond channels for picoliter chemical transfer or storage is proposed. Narrow micro-fluidic channels made completely of poly-C have been fabricated for the first time. [Copyright &y& Elsevier]

The polytetrafluoroethylene (PTFE) composites filled with CaF2 gas are ablated by laser beam instead of arc and the microstructure and the contents of the main elements on the ablated surfaces of PTFE composites are analysed through scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The mechanism of the resistance to laser ablation influenced by CaF2 is studied. The results indicate that it exists an optimum content of CaF2 at which PTFE acquires a relatively high resistance to laser radiation; the optimum content of CaF2 could improve the reflectivity, regulate absorption of laser energy and improve PTFE composites resistance to laser ablation. [ABSTRACT FROM AUTHOR]

Abstract: To reduce the cost of Bi-2223 superconducting tapes, we prepared Bi-2223 tapes by the powder-in-tube process using a bimetallic sheath consisting of Ag and Ni. Ag was in contact with the superconducting ceramic core and acted as a protective layer against reaction between the external Ni sheath and the internal superconducting core. We remove Ni on one edge of the tape in order to provide a path for oxygen diffusion. After two step heat treatments, the critical current density of sample is 9307Acm−2. SEM photographs and XRD results show that there are some Bi-2212 phase in samples conducted two step heat treatments. It is suggested that the heat treatment process should be optimized in the future research in order to decrease the thickness of NiO layer, to reduce the fraction of Bi-2212 phase, and to improve superconducting performance of Bi-2223/Ag/Ni tape. [Copyright &y& Elsevier]