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Pb(Nd x Zr 0.52 Ti 0.48 )O 3 (PNZT) (x = 0%, 1%, 2%, 3%, 4%, 5%) thin films were prepared by sol-gel process to investigate the effects of neodymium substitution on crystalline orientation, microstructure and electric properties of lead zirconate titanate (PZT) films. X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis showed that PNZT films with Nd doping concentration below 3% exhibited dense perovskite structure with (100) preferred orientation. The average grain size of PNZT films decreased as the Nd substitution increased. The maximum dielectric constant, remnant polarization and minimum coercive field were obtained in 2% Nd-doped PZT films. Fatigue resistance was also improved significantly with 2% Nd dopant. [ABSTRACT FROM AUTHOR]

Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is applied to study orientation structures of polydimethylsilane (PDMS) films deposited on heteroatom-doped graphite substrates prepared by ion beam doping. The Si K -edge NEXAFS spectra of PDMS show opposite trends of polarization dependence for non irradiated and N 2 + -irradiated substrates, and show no polarization dependence for an Ar + -irradiated substrate. Based on a theoretical interpretation of the NEXAFS spectra via first-principles calculations, we clarify that PDMS films have lying, standing, and random orientations on the non irradiated, N 2 + -irradiated, and Ar + -irradiated substrates, respectively. Furthermore, photoemission electron microscopy indicates that the orientation of a PDMS film can be controlled with microstructures on the order of μm by separating irradiated and non irradiated areas on the graphite surface. These results suggest that surface modification of graphite using ion beam doping is useful for micro-orientation control of organic thin films. [ABSTRACT FROM AUTHOR]

Experimental pole figures are an important input for microstructure homogenization models. In this paper, we derive an exact analytical formulation to quantify the uncertainties in homogenized properties due to uncertainty in the experimentally measured pole figures. The pole figures are acquired from a set of Ti-7Al alloy samples. These samples were obtained from the same process: by compressing a beta forged ingot at room temperature followed by annealing. The samples were taken from different regions of the original ingot, and this created variability in the resulting pole figures. The joint multivariate probability distributions of the computed orientation distribution function (ODF) is then found using the method of characteristic functions based on a Gaussian model of the pole figures. Engineering properties such as elastic modulus can be obtained by volume averaging over the ODF. We also show that uncertainty in elastic properties can be analytically obtained using direct transformation of random variables in the homogenization approach. [ABSTRACT FROM AUTHOR]

Functional micro-structures on laser-ablated carbon fibre reinforced composites surfaces exhibit distinct advantages. A variety of fibre endings with different orientations may coexist on the C/SiC sectional plane, the anisotropic nature of C/SiC (carbon fibre reinforced silicon carbide) composites present a new challenge to the laser ablation process. However, few reports describing the influence of the fibre ending orientations on the laser-ablated C/SiC surface topography could be found. In this investigation, micro-ridges were established on three typical C/SiC surfaces by laser ablation, and a comparative study was performed to identify the topography variations on these laser-ablated C/SiC surfaces. The results showed that C/SiC surfaces with different fibre ending orientations present distinct surface characters ( Sz , Sq ) after laser ablation. Although all of the laser ablation processes are similar in nature, the fibre ending variation made the laser and material interaction different greatly. Attention should be devoted to the influence of the fibre ending orientation on surface topography formation before performing the laser ablation of carbon fibre reinforced composite materials. Finally, some typical surface defects on these laser-ablated surfaces were also discussed. [ABSTRACT FROM AUTHOR]

Chalcogenide films can be used in thin-film solar cells due to their high photoelectric conversion efficiencies. It was difficult to identify one abnormal phase with high X-ray diffraction (XRD) intensity and preferred orientation in the samples for preparing chalcogenide films by spin-coating and co-reduction on soda-lime glass () substrates. The raw materials and reductant are metal chlorides and hydrazine hydrate respectively. In order to identify this phase, a series of experiments were done under different conditions. The phases of obtained products were analyzed by XRD and the size and morphology were characterized by scanning electron microscope (SEM) and atomic force microscopy (AFM). From the experimental results, first it was proved that the abnormal phase was water-soluble by water immersion experiment, then it was identified as NaCl crystal through XRD, energy dispersive spectrometer (EDS) and SEM. The cubic NaCl crystals have high crystallinity with size lengths of about 0.5-2m and show a 100 preferred orientation. The reaction mechanism of NaCl crystal was proposed as follows: The NaCl crystal was formed by reaction of Na2O and HCl in a certain experimental conditions. [ABSTRACT FROM AUTHOR]

While it is well known that fatigue crack growth in metals that display confined slip, such as high strength aluminium alloys, develop crack paths that are responsive to the loading direction and the local microstructural orientation, it is less well known that such paths are also responsive to the loading history. In these materials, certain loading sequences can produce highly directional slip bands ahead of the crack tip and by adjusting the sequence of loads, distinct fracture surface features or progression marks, even at very small crack depths can result. Investigating the path a crack selects in fatigue testing when particular combinations of constant and variable amplitude load sequences are applied is providing insight into crack growth. Further, it is possible to design load sequences that allow very small amounts of crack growth to be measured, at very small crack sizes, well below the conventional crack growth threshold in the aluminium alloy discussed here. This paper reports on observations of the crack path phenomenon and a novel test loading method for measuring crack growth rates for very small crack depths in aluminium alloy 7050-T7451 (an important aircraft primary structural material). The aim of this work was to firstly generate short- crack constant amplitude growth data and secondly, through the careful manipulation of the applied loading, to achieve a greater understanding of the mechanisms of fatigue crack growth in the material being investigated. A particular focus of this work is the identification of the possible sources of crack growth retardation and closure in these small cracks. Interpreting these results suggests a possible mechanism for why small fatigue crack growth through this material under variable amplitude loading is faster than predicted from models based on constant amplitude data alone. [ABSTRACT FROM AUTHOR]

The phenomenon of restrained stress-induced preferential orientation of S′ precipitates is investigated using a single-crystal of Al–1.23Cu–0.43 Mg alloy. Al–1.23Cu–0.43 Mg single-crystal specimens are subjected to stress aging, and the microstructure is analyzed by transmission electron microscopy (TEM). It is found that the stress-induced preferential orientation of S′ precipitates is restrained owing to the dislocations produced by a higher stress. The effect of dislocations on the oriented precipitates depends on the total length of the intersection lines for precipitate habit planes and dislocation glide planes. This investigation not only provides important insight into solving the anisotropy problem attributed to precipitation strengthening, but also offers a benchmark for choosing the appropriate stress range in manufacturing of Al–Cu–Mg alloys. [ABSTRACT FROM AUTHOR]

The resolution dependence of orientation gradients was studied in a well-annealed 99.9995% pure polycrystalline copper pulled to failure in tension. Owing to the well developed neck, different regions in the sample correspond to different tensile strains. Post-mortem characterization was performed using EBSD on cross-sections containing the tensile axis. Kernel average misorientation (KAM) was calculated as a metric to establish correlation between defect accumulation and microstructural features, with a threshold of 5° to focus on intra-granular gradients. The region with the lowest strain (2%) showed high KAM values adjacent to grain boundaries compared to the grain interior, regardless of the point spacing, i.e. the spatial resolution. However, in the region with the highest strain (13%) a strong dependence on resolution was found. For point spacings of 0.5 μm or smaller, the same correlation of high KAM with locations near boundaries was found. At coarse spacings i.e. low spatial resolution, by contrast, the reverse was found in that the highest KAM values appear in the grain interiors, as previously observed in X-ray microscopy on the same sample which had a similar coarse resolution. An analysis of orientation gradients parallel to, and perpendicular to boundaries suggested that the latter tend to be the larger of the two. This helps to explain why boundary-adjacent points have low KAM values. The conclusion is that measurement of local orientation gradient requires a resolution that is comparable to the dislocation substructure. [ABSTRACT FROM AUTHOR]

The microstructural and textural evolutions together with the orientation dependencies of mechanical properties of the extruded Mg–6Li–1Zn (LZ61), Mg–8Li–1Zn (LZ81) and Mg–12Li–1Zn (LZ121) alloys were investigated. The shear punch testing (SPT) method was employed to evaluate the room- and high-temperature (200–300 °C) mechanical anisotropy of the extruded materials. Microstructural analysis revealed that, despite a great discontinuous dynamic recrystallization (DDRX) occurred in the extrusion direction (ED) and normal direction (ND), the microstructural anisotropy was observed in all extruded materials, the effect which was more pronounced in the LZ81 alloy by developing banded structure in the ND condition. Textural studies in both hcp LZ61 and LZ81-α phase showed a fiber-type texture with the basal planes being parallel to the ED after extrusion. For the LZ81 alloy, however, the interfering presence of β phase affects the LZ81-α-phase texture by reducing the intensity of the maximum orientations of the basal and prismatic planes. Similar weakened bimodal type texture was formed in the bcc-structured LZ81-β phase, where some <110> poles were located parallel to the ED along with developing some other poles of a fiber-type character. It was also found that the abnormal grain growth might have been encouraged by the strong texture developed in the extruded LZ121 alloy. The SPT results indicated that the texture-dependent hcp LZ61 alloy showed higher shear strength in the ND condition than the ED condition, caused by the texture strengthening effect. As the Li content and deformation temperature increase, the texture dependence of strength properties, and thus, the mechanical anisotropy, decrease so that the LZ121-ND sample showed lower shear strength than the ED specimen due to the greater grain sizes achieved in the ND condition. [ABSTRACT FROM AUTHOR]

The bending mechanical behaviors of Ag nanowires with different microstructures and surface orientations are investigated via molecular dynamics simulations. Our results show the fivefold twin boundary strongly hinders the dislocation motion, leading to the dislocation pile-ups at twin boundaries which is different from the results from tensile tests in which the fivefold twin boundary does not act as the substantive barriers for dislocation propagation and the dislocations can easily pass through twin boundary. The fivefold twin boundary strengthens the nanowires by strain hardening. In single crystalline nanowires, the dislocation nucleation sites and dislocation characteristics are determined by the loading directions and surface orientations. The different dislocation characteristics lead to different ductility when the same nanowire is loaded along different directions. The first order effect of surface orientation on the dominant deformation mode has not been observed in the present work. The stress gradient plays an important role on the different results observed under tension and bending. [ABSTRACT FROM AUTHOR]

Due to their remarkable mechanical properties, carbon nanotube (CNT) reinforced aluminum (Al) matrix composites have attracted a wide range of research interests. This work attempts to experimentally and numerically investigate the relationship between the micro-structures and mechanical behavior of CNT/Al composites. Three-dimensional (3D) computational structural modeling of CNT/Al composites is performed, in which the size, morphology, orientation, location and volume fraction of CNTs are reproduced to be similar to those of the actual micro-structures of CNT/Al composites. The strengthening of the mechanical properties of the constituent materials of CNT/Al composites and reasonable load and boundary conditions are studied based on the models of CNT/Al composites developed. The tensile mechanical behavior of CNT/Al composites is numerically evaluated and experimentally verified. Results show that the enhanced mechanical properties of CNT/Al composites can be attributed to three factors: CNT reinforcements, matrix grain refinement and layered architectures. Through the microscopic structural modeling methods presented herein, the effects of model size, interfacial behavior, volume fraction of CNTs and layered structures on the mechanical behaviors of CNT/Al composites can be reproduced to understand the strengthening and deformation mechanisms of CNT/Al composites. [ABSTRACT FROM AUTHOR]

Potential applications of diamond-like carbon (DLC) coatings range from precision tools and biomedical implants to micro mechanical devices and engine components. Where uniform coatings are required on substrates with complex geometries, plasma enhanced chemical vapour deposition (PECVD) is often a preferred deposition method. As a non-line of sight process, the geometry of the substrate is often considered negligible. For this reason analysis of PECVD coatings, such as amorphous carbon, has mostly been concerned with reactor deposition variables, such as bias voltage, pressure and gas ratios. Samples are therefore usually prepared and positioned to minimise the influence of other variables. By depositing nominally similar DLC films on silicon samples positioned horizontally and vertically on the reactor cathode plate it was possible to examine the variations in the coating characteristics and mechanical properties that occur due to the geometry of the substrate being coated. Topographic measurements and analysis of bonding structures revealed significant heterogeneity in the coatings. Electron microscopy showed variation in surface structure as well as thickness disparities of up to 50% in the vertical sample. Atomic force microscopy showed roughness, Ra, varied from 0.37 nm to 15.4 nm between samples. Raman spectroscopy highlighted variations in the sp²/sp³ bonding ratios whilst micro wear tests demonstrated how these variations reduce the critical load performance. These effects are explained in terms of the deposition mechanisms involved and are related to variation in deposition species and geometrical field enhancements within the deposition chamber. Improved understanding of these local variations will aid in the optimisation of coatings for complex substrate geometries. [ABSTRACT FROM AUTHOR]

The transition zone (TZ) between the skin and core of Toray T700 carbon fiber was investigated by transmission electron microscopy. The higher basal-plane orientation was identified in the TZ compared with the skin and core, but it disappeared after heat treatment at 2800 °C. Plasmon peak energy in the TZ was higher than that in the skin and core about 0.7–0.8 eV, indicating the TZ with higher density. No element concentration existed in the TZ. The TZ with strong contrast manifests itself before and after heat treatment, and formation mechanism of its strong contrast was proposed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Spray deposition process was used to produce Al alloys with excellent performance. [•] The deposited alloys exhibited a high strength of 690MPa and elongation up to 17.2%. [•] The η′ phase was coherent with α-Al and their orientation relationship was studied. [•] The interface misfits and the transition matrixes of two phases were calculated. [Copyright &y& Elsevier]

Abstract: Al–40% Cu hypereutectic alloy samples were successfully directionally solidified at a growth rate of 10μm/s in different sizes (4mm, 1.8mm, and 0.45mm thickness in transverse section). Using the serial sectioning technique, the three-dimensional (3D) microstructures of the primary intermetallic Al2Cu phase of the alloy can be observed with various growth patterns, L-shape, E-shape, and regular rectangular shape with respect to growth orientations of the (110) and (310) plane. The L-shape and regular rectangular shape of Al2Cu phase are bounded by {110} facets. When the sample size was reduced from 4mm to 0.45mm, the solidified microstructures changed from multi-layer dendrites to single-layer dendrite along the growth direction, and then the orientation texture was at the plane (310). The growth mechanism for the regular faceted intermetallic Al2Cu at different sample sizes was interpreted by the oriented attachment mechanism (OA). The experimental results showed that the directionally solidified Al–40% Cu alloy sample in a much smaller size can achieve a well-aligned morphology with a specific growth texture. [Copyright &y& Elsevier]

A high-purity predominantly single crystalline zirconium was subjected to controlled focused ion beam (FIB) damage. Damage estimates were obtained from electron backscattered diffraction (EBSD) and nano-indentation measurements on exactly the same area/orientation. The damage kinetics, between different crystallographic orientations, differed by one order of magnitude and a clear hierarchy of orientation sensitive ion damage emerged. Use of a simple geometric approach, linear density of atoms and corresponding scattering cross-sections to impinging gallium ions, could differentiate between extreme damage kinetics; but failed when such differences were relatively minor. Numerically intensive molecular dynamics (MD) simulations, on the other hand, were more effective. However, MD simulations or direct EBSD observations failed to justify anisotropic irradiation hardening (AIH): 3–8 times more hardening for near basal. Though explanation for AIH is indirect, evidence and rationalization for orientation-sensitive radiation damage appears clear and statistically reproducible. [ABSTRACT FROM AUTHOR]

Highlights: [•] Aluminizing treatment decreased the creep strength of superalloy. [•] Long-term exposure deteriorated the creep strength of coated superalloy. [•] Surface orientation affected the creep lifetime of coated superalloy. [•] Fracture deformation mechanism in coated superalloy was discussed. [Copyright &y& Elsevier]

Highlights: [•] Microspectroscopic investigation of pentacene-based OFETs during operation. [•] Correlation of micromorphology with charge trapping. [•] Distinction between orientation and charge-induced effects. [ABSTRACT FROM AUTHOR]

Abstract: Epitaxially grown thin films with nominal composition Ni50Mn30Ga20 and thickness 1.5μm were prepared on MgO(100) substrate with a Cr buffer layer by DC magnetron sputtering. The surface layer microstructures of the as-deposited thin films consist of non-modulated (NM) martensite plates with tetragonal structure at ambient temperature, which can be classified into the low and high relative contrast zones of clustered plates (i.e. plate colonies) with parallel or near-parallel inter-plate interface traces in secondary electron images. Orientation analyses by electron backscatter diffraction revealed that individual NM plates are composed of alternately distributed thicker and thinner lamellar variants with (112)Tetr compound twin relationship and coherent interlamellar interfaces. In each plate colony, there are four distinct plates in terms of the crystallographic orientation of the thicker lamellar variants and therefore, in total, eight orientation variants. For the low relative contrast zones, both thicker and thinner lamellar variants in adjacent plates are distributed symmetrically across their inter-plate interfaces (along the substrate edges). At the atomic level, there are no unbalanced interfacial misfits and height misfits, resulting in long and straight inter-plate interfaces with homogeneous contrast. However, in the high relative contrast zones, the thicker and thinner lamellar variants in adjacent plates are oriented asymmetrically across their inter-plate interfaces (at ∼45° to the substrate edges). Significant atomic misfits appear in the vicinity of the inter-plate interfaces and in the film normal direction. The former result in bending of the inter-plate interfaces, and the latter give rise to the high relative contrast between adjacent plates. [Copyright &y& Elsevier]

Abstract: By means of the stress–strain finite element method (FEM) in elastic–plastic regime, the influences of the applied stress on the distribution of von Mises stress and evolution of shape regularity of γ′ phase in a [011] oriented single crystal nickel-based superalloy are investigated. Results show that, after full heat treatment, the microstructure of [011] oriented single crystal superalloy consists of the cuboidal γ′ phase embedded coherently in the γ matrix phase, and on (100) plane aligned regularly at angle of 45° relative to the [011] orientation. During compressive creep, the cuboidal γ′ phase is transformed into the mesh-like lamellar rafted structure on (100) plane. Therefore, the changes of the lattice strain, the strain energy density and interfacial energy are thought to be the driving forces of the element diffusion and γ′ phase directional growth. During compressive creep, the lattice contraction occurs on (100) plane of the cuboidal γ′ phase along [001] and [010] directions, whose extruding effect may repel Al, Ti atoms with bigger radius. Therefore, the expanding strain of lattices along [100] direction on (010) and (001) planes of the cuboidal γ′ phase may trap Al, Ti atoms to promote the directional growth of γ′ phase on (100) plane along [001] and [010] directions, which is thought to be the main reason for the γ′ phase growing directionally into the mesh-like lamellar structure. [Copyright &y& Elsevier]

A nanostructured eutectic Ag–Cu alloy with alternate Ag and Cu lamellae was processed by surface mechanical attrition treatment (SMAT). The orientation/phase distributions of the eutectic Ag–Cu before and after SMAT were investigated using transmission electron microscopy combined with automated crystal orientation mapping. After SMAT, the top surface layer was transformed into a composite with isolated Cu phase dispersed in Ag. The interphase boundaries in the top surface layer were changed from the original cube-on-cube and hetero-twin orientation relationships into general large-angle boundaries accordingly. [ABSTRACT FROM AUTHOR]

The evolution of the orientation relationship between mechanical twins and the surrounding matrix with the degree of plastic deformation has been characterized at the nanoscale in twinning-induced plasticity steel. The recently developed automated crystal orientation mapping in transmission electron microscopy revealed that the ideal twin relationship is retained up to large levels of strain, while large orientation gradients are built up within the matrix. This particular evolution undoubtedly plays a role in the large work hardening rate of these steels. [Copyright &y& Elsevier]

Abstract: A range of silica nanofibers with refined mesoporous microstructures were successfully synthesized via the combination of electrospinning and the sol–gel method. It was found that the concentration of nonionic surfactant Pluronic F127 (EO106PO70EO106) significantly influenced the morphology and mesoporous structure of silica nanofiber. With the reduced F127/Tetraethyl orthosilicate (TEOS) mass ratio, from 0.28 to 0.14, the diameter of silica nanofibers decreased from 453nm to 130nm, and more importantly, the size and the orientation of the internal mesopores were remarkably regulated. It has therefore been a critical step forward to a new hierarchical silica fiber for modern optical and biomedical applications. [Copyright &y& Elsevier]

Abstract: Microstructural evolution was studied in a near-lamellar two phase (α2+γ) Ti–47Al–2Cr–2Nb alloy under high temperature creep and exposure conditions. The aim of this study was to probe the role of stress orientation, with respect to lamellar plates, on microstructural changes during primary creep. Creep testing was complemented with SEM and TEM based microstructural characterization. It was observed that retention of excess α2 resulted in an unstable microstructure. Under stress and temperature, excess α2 was lost and Cr-rich precipitates formed. Depending on stress orientation, the sequence of precipitates formed was different. α2 loss was accompanied by formation of the non-equilibrium C14 Laves phase when lamellar plates were oriented parallel to the stress axis. In contrast, α2 loss did not result in formation of the C14 phase in perpendicular samples. It was concluded that C14 formed preferentially in certain test orientations because of its effectiveness in relieving residual stresses in α2 that arose from lattice misfit and modulus mismatch. [Copyright &y& Elsevier]

Abstract: The TiO2 films were prepared on Pt/Ti/SiO2/Si substrate by a laser chemical vapor deposition method. With increasing laser power (P L) from 48 to 98W, the deposition temperature (T dep) monotonously increased from 849 to 929K. At T dep=849K (P L=48W), the rutile TiO2 film was prepared with strong (110) and (200) peaks. With increasing T dep from 849 to 883K (P L=71W), the intensity of (110) peak increased. The (110)-oriented TiO2 films were obtained for T dep beyond 903K (P L=81W). All TiO2 films showed faceted grains with the columnar cross-section. With increasing T dep, the grain size increased and the column became wider. The high deposition rate (R dep) ranged from 13.04 to 24.84μmh−1. [Copyright &y& Elsevier]

Abstract: Morphological changes caused by deformation and orientation of different domains of polystyrene-b-polybutadiene-b-poly(methyl methacrylate), SBM, triblock terpolymers were investigated using in-situ small angle X-ray scattering (SAXS), tensile testing, and transmission electron microscopy (TEM). Two sets of SBM triblock terpolymers with similar weight fractions of the three blocks were studied. The two sets differ in terms of their molecular weights. Each set contained two SBM differing in their polybutadiene isomers (1,2- and 1,4-B). Results showed that for 1,2-B based SBMs the polybutadiene block forms cylindrical domains which coalesce in the glassy lamellar matrix of the two glassy outer blocks whereas the lower molar mass 1,4-B based SBM forms mixed S/M and the higher one forms well segregated long range ordered lamellae. These morphological differences indicate that the deformation and the orientation behavior of the polymers'' domains differ. In 1,2-B based SBMs yielding at high stresses was followed by a stress drop after the yield point. The other polymer type showed homogeneous deformation of the lamellar domains at their yield point. 2D-SAXS during deformation of the triblock terpolymers showed an anisotropic deformation pattern in the 1,2-B SBMs, whereas four point SAXS patterns were found for the 1,4-B SBMs. Further studies showed that the fragmented lamellar planes of the lower molar mass 1,2-SBM oriented randomly whereas the orientation of the lamellar planes of the higher molar mass 1,2-B SBM was parallel to the strain direction. The alignment of the lamellar planes of 1,4-B SBMs were randomly distributed in the unstretched state. [Copyright &y& Elsevier]

Abstract: Components exposed to the flow of liquid solutions containing hard particles experience significant material loss. For defined slurry conditions, the extent of damage to the components depends upon their microstructure and the slurry particle impingement angles. This paper presents the research work carried on to develop a gas metal arc welding (GMAW) clad overlay that resists slurry erosion at both low and high particle angles. GMAW overlays containing hard primary Fe2B crystals in a supporting matrix enriched in molybdenum, carbon and silicon have been considered. Cored wires of specific compositions deposited with adapted welding parameters produce weld overlays presenting a peculiar microstructure. These iron boride-based overlays contain fine elongated boride crystals aligned mainly perpendicularly to the wearing surface. This peculiar microstructure is responsible for the outstanding slurry erosion resistance observed at both impinging angles of 30° and 90°. These iron boride-based overlays present a slurry erosion resistance at low and high impinging angles far beyond that observed with known materials including chromium carbide overlays. [Copyright &y& Elsevier]

Abstract: Single-crystalline-like epitaxial germanium thin films with hall mobility values as high as 833cm2/Vs have been demonstrated on inexpensive polycrystalline metallic substrates. The dependence of mobility of p-type and n-type germanium films on the deposition temperature has been examined and correlated to microstructural changes. The importance of crystallographic orientation of Ge to achieve these high mobility values has been verified. The mobilities of the epitaxial germanium films on the film thickness for p-type and n-type films with multi-layer architecture with different epitaxial intermediate layers have been investigated. Results show that the increased mobility with increasing germanium film thickness is not just due to crystallographic texture improvement, but could also be a result of decreasing defect density. [Copyright &y& Elsevier]

Abstract: High-resolution electron microscopy was used to research the age-hardening behaviors in 6005A alloy and the microstructural characterizations of precipitates. It was found that β″, β′ and Q′ precipitates had 12 orientation variants, respectively, the smaller size and a high-density β′′ precipitates existed in alloy for a long time, which played a very important role in controlling an anti-overaged softening behavior in 6005A alloy. Further, by the crystallographic interface and morphology analysis, a main reason was that a 2-dimensions coherency strain-field not only had the high-density β′′ precipitates become the biggest obstacle of dislocations movement, but also made them transform into β′ and Q′ precipitates with more difficulty. Moreover, it was also found that β′ and Q′ precipitates had weaker relatively strain-fields, the larger size and a lower density, which were largely associated with the reduction in hardness that occurred upon overaging. Further, the strengthening of precipitates on alloys could be summarized as: β″>Q′>β′. Based on the structural information, the quantitative Moiré fringes analytical technique was also used to verify the lattice parameters and orientation of precipitates. [Copyright &y& Elsevier]

The effect of crystal orientation on the microstructure of a nickel-based crystalline superalloys during directional solidification was explored. Differently oriented crystals with [001] and [011] orientations were fabricated with seeding technique. The results showed that primary dendrite arm spacings decreased simultaneously with the increase of misroientation. The primary dendrites arrange in lines in [011] single crystal. For [001] oriented crystals, the size of γ′ phase increased with the increasing of misorientation. However, it was observed that the size of γ′ decreased with large misorientation for [011] orientated growth. Meanwhile, more γ′ in [011] crystals tended to be triangular. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Abstract: The influence of the crystallographic orientation of Sn–3.0wt%Ag–0.5wt%Cu flip-chip joints and underfill on electromigration was investigated. The current density applied in our tests was 15kA/cm2 at 160°C. Various times to failure of the test samples show a clear dependence of the electromigration behavior on the Sn grain orientations. Different microstructural evolutions were observed in all solder bumps in correlation with the crystallographic orientations of the Sn grains after an electromigration test. The primary failure of the solder joints was caused by dissolution of the Cu electrode at the cathode interface. Rapid dissolution of the Cu electrode occurred when the c-axis of the Sn grains was parallel to the direction of electron flow. On the other hand, slight dissolution of the Cu electrode was observed when the c-axis of the Sn grains was perpendicular to the direction of electron flow. Some grain boundaries interrupt the migration of Cu and the trapped Cu atoms form new grains of intermetallic compounds at the grain boundaries. In addition, underfill inhibits serious deformation of solder bumps during current stressing. [Copyright &y& Elsevier]