Exceptionally high tensile ductility of commercial Mg alloy ZK60 is reported. It was achieved by equal channel angular pressing without any extra processing steps. The tensile ductility at 220 °C was 2040% and 1400% for the strain rates of 3 × 10−4 s−1 and 3 × 10−3 s−1, respectively. The strain rate sensitivity of the flow stress exhibited a value slightly above 0.5, which is characteristic of superplastic deformation. The grain structure associated with this behavior was shown to be bi-modal with further separation in two fractions with different grain sizes within the small grain size population.

We report enhanced thermal stabilities of nanostructured Cu films containing insoluble tungsten carbides prepared by sputter deposition. Tungsten carbides in the form of W2C are present in the supersaturated solid solution of Cu, as confirmed by x-ray photoelectron spectroscopy, scanning electron microscopy, and x-ray diffraction analyses. Focused ion beam analysis revealed that the films are thermally stable during annealing when they are in contact with Si without a diffusion barrier, and the copper silicide was not formed up to an annealing temperature of 400 °C. Leakage current characteristic evaluation on SiO2/Si metal oxide semiconductor (MOS) structure also revealed the superior reliability of Cu with a dilute amount of tungsten carbides, indicating their usefulness in advanced barrierless metallization applications. The films with higher amount of tungsten carbides exhibited good thermal stability at high temperatures and could be rationalized as a consequence of a refined grain structure together with the strengthening effect of W2C.

In this study, we investigated the vibration properties of Sn–Zn and Sn–Zn–Al alloys. It is notable that, with a small amount of Al addition, Sn whiskers were generated during resonant vibration. This may be the first time that Sn whiskers were found on bulk materials. Microstructural refining and hardening caused by alloying of Al stunted the fiberous type Sn deformation within Sn–Zn eutectics. Vibration-induced extrusion of Zn-free regions in the vicinity of cell boundaries may account for the appearance of the whiskers.

The critical parameters for the structural stability of physical vapor deposited TiN film on (1120) sapphire were investigated by analyzing the adhesion strength and failure mechanism through in situ observations of the fracture sequence during scratch tests and static normal indentation. TiN was deposited by arc ion plating on (1120) sapphire, and the thickness of the TiN film was controlled to 700 nm. Delamination of TiN film was monitored in situ from below the contact through a transparent sapphire substrate, using zoom optics mounted into a video imaging sensor. In situ observation enables us to detect the failure origin of TiN coating on sapphire. The failure origin of TiN film on (1120) sapphire was identified as both rhombohedral and basal twinning of the sapphire substrate. Rhombohedral twinning was initiated first, and basal twinning ensued. Twinning-induced plastic deformation of the sapphire substrate triggered the initiation of interfacial delamination of the TiN coating. The plastic deformation of the substrate ultimately induced failure of the protective coating.

The oxidation kinetics of Cu60Zr30Ti10 bulk metallic glass and its crystalline counterpart were studied in oxygen environment over the temperature range of 573–773 K. The oxidation kinetics, measured with thermogravimetric analysis, of the metallic glass follows a linear rate law between 573 and 653 K and a parabolic rate law between 673 and 733 K. It was also found that the oxidation activation energy of metallic glass is lower than that of its crystalline counterpart. The x-ray diffraction pattern showed that the oxide layer is composed of Cu2O, CuO, ZrO2, and metallic Cu. Cu enrichment on the topmost oxide layer of the metallic glass oxidized at 573 K was revealed by x-ray photoelectron spectroscopy while there was a decrease in Cu content in the innermost oxide layer. The oxide surface morphologies observed from scanning electron microscopy showed that ZrO2 granules formed at low temperatures while whiskerlike copper oxides formed at higher temperatures.

High-mobility molybdenum-doped In2O3 films (IMO) were prepared on the normal glass substrate by reactive direct current magnetron sputtering from the molybdenum-embedded indium metal target. The effects of oxygen partial pressure, substrate temperature, and sputtering current on the optoelectrical properties of IMO films were investigated. The films with the highest carrier mobility of 50 cm2 V−1 s−1, as well as the average visible transmission greater than 80% including the 1.2-mm-thick glass substrate, were obtained. The minimum resistivity of the films is 3.7 × 10−4 ohm cm. The properties of the IMO films are sensitive to the oxygen partial pressure in the sputtering environment. X-ray diffraction measurements indicate that the films show In2O3 crystal structure.

Eu3+-doped Lu2O3 phosphors were synthesized through a novel solution combustion route using glycine as the fuel. The influence of the glycine-to-nitrate (G/N) mole ratio on the crystallite size, specific surface area, morphology, and photoluminescence of the synthesized phosphors was investigated. The ignition temperature on the properties of the products was also studied. With G/N ratio increasing from 1.0 to 1.7, the grain size increased from 35 to 118 nm accordingly, resulting in the obvious changes of the photoluminescence properties. Concentration dependence of the emission intensity revealed that the quenching concentration of europium dopant was around 5 mol% for G/N- 1.7. The intensity of the peak emission due to the 5D0 → 7F2 transition of the Eu3+ ions dropped as the grain size decreased. The charge transfer band position of Eu3+-doped lutetia phosphors shifted toward lower energy (red shift) with the reduction of crystallite sizes and also with the increase of Eu3+ concentrations.

A modified and convenient route using microemulsions (avoiding Ba-alkoxide) was evolved for the synthesis of uniform and monodisperse nanoparticles of BaTiO3 at low temperature (800 °C). X-ray line broadening and transmission electron microscopy studies show that the particle size varies in the range of 20–25 nm. Evidence for tetragonal distortion was found in these nano-sized (20–25 nm) particles of barium titanate from careful x-ray diffraction studies as well as from Raman spectroscopy. Our study showed that the critical size of the cubic to tetragonal transition in barium titanate may be much lower than suggested theoretically. The grain size showed an increase on sintering of 35 nm at 900 °C to 120 nm at 1100 °C, which was much lower than the grain size obtained at this temperature by the normal solid state route. The dielectric constant depends on sintering temperature and was found to increase from 210 (900 °C sintering) to 520 (1100 °C sintering) at 100 kHz. The dielectric constant was highly stable with temperature as well as frequency.

The high-temperature indentation fracture and microstructures of dysprosium niobate (DyNbO4) were investigated by optical, scanning, and transmission electron microscopy (OM, SEM, and TEM). Polycrystalline samples were sintered at 1350 °C for 3 h and cut into 3 mm disks for TEM. The disks were indented in a Nikon QM (Tokyo, Japan) hot hardness indenter at room temperature up to 1000 °C. Many lamellar twins having different widths were observed by TEM as well as intergranular microcracks. The room temperature hardness was relatively low at 5.64 GPa and decreased with elevated temperatures. Crack lengths were short, showing a typical micro-cracking effect. In the sample indented at 1000 °C, dislocations in periodic arrays were evident, and their density increased markedly due to heavy plastic deformation.

Lead zirconate titanate (PZT) films of composition close to the morphotropic phase boundary were deposited onto standard Si/SiO2/Ti/Pt substrates using a modified sol-gel process. The preparation conditions were optimized to obtain high-quality films at sufficiently low temperature (Ta - 500 °C). The dielectric, ferroelectric, and piezoelectric properties of the films were then measured as a function of the annealing temperature and the number of distillations to evaluate their suitability for micromechanical applications. The maximum values of the longitudinal charge and voltage piezoelectric coefficients were d33 ∼ 65 pm/V and g33 ∼ 4 × 10−3 Vm/N, respectively. The results indicate that the piezoelectric properties improved and became saturated with increasing number of distillations and are almost independent on Ta. Only moderate decrease of the piezoelectric response with frequency suggests that the investigated PZT films can be used in high-frequency piezoelectric applications. The results are discussed in terms of the microstructure and interface effects on the piezoelectric deformation in ferroelectric thin films.

The leaching of Cs from well-characterized Cs-bearing hollandite powders with ideal formula Cs0.8Ba0.4Ti8O16 was studied at 200 °C under static oxidizing conditions achieved using dilute nitric acid solutions. A variety of techniques were used to elucidate the leaching mechanism including x-ray powder diffraction, magnetic susceptibility, x-ray absorption near edge structure, and electron microscopy. Under the conditions of the study, Cs is leached from Cs-hollandite according to a deceleratory rate law with contracting geometries. The principal reaction products are rutile and brookite. The leaching mechanism involves the formation of a quasi-continuous, and hence relatively impermeable, secondary titanium oxide phase (rutile and/or brookite) on the surfaces of the hollandite crystallites. The driving force for the leaching reaction appears to be the oxidation of Ti3+ in the structure by the oxidizing acid, which then promotes extraction of Cs and Ba from the hollandite tunnels followed by tunnel destabilization and transformation to rutile and brookite.

The superplastic behavior of the Zr65Al10Ni10Cu15 glass metallic alloy produced by the powder metallurgy method was examined in the supercooled liquid region. A tensile elongation as large as 750% was obtained at 6.3 × 10−3 s−1 at 697 K. Large strain hardening took place during the course of deformation and systematic trend was observed in the hardening behavior. Plots of stress versus strain and strain rate versus stress at 697 K showed that Newtonian viscous flow governed the plastic flow until the onset of strain hardening. Microstructure and differential scanning calorimetry analyses as well as flow stress versus testing time curves provided consistent evidence that the strain hardening was induced by crystallization. Crystallization was enhanced in the gauge region (deformed region) as compared to the grip region (undeformed region). Crystallization is expected to decrease tensile ductility by decreasing the strain-rate-sensitivity value and increasing the degree of brittleness. Hardening by crystallization, however, can contribute to neck stability if crystallization is enhanced in the neck region. The strain hardening and plastic stability parameters were measured as a function of strain for different strain rates at 696 K. The strain hardening parameter remained highly positive until failure. Because of this, the neck stability parameter (I) could be I < 0 in the entire hardening region. The contribution of hardening by crystallization to neck stability was found to be much more significant than that by grain growth in the superplastic metallic alloys. Reducing the specimen heating-and-holding time was suggested to promote superplasticity deformation without delaying initiation of crystallization. The largest tensile strain in the hardening region where crystallization may be obtained at the strain rates and temperatures where crystallization rate is controlled to be the lowest while maintaining I ≤ 0 throughout deformation.

Researchers have constructed a number of DNA-based nanodevices that undergo stepped configuration changes through the application of single-stranded DNA oligomers. Such devices can be incorporated into gel networks to create new classes of active materials with controllable bulk mechanical properties. This concept was demonstrated in a DNA-crosslinked gel, the stiffness of which was modulated through the application of DNA strands. Each crosslink incorporated a single-stranded region to which a DNA strand with a complementary base sequence (called the fuel strand) bound, thereby changing the nanostructure of the gel network. The gel was restored to its initial stiffness through the application of the complement of the fuel strand, which cleared the fuel strand from the crosslink via competitive binding. Stiffness changes in excess of a factor of three were observed. The ability to switch the mechanical properties of these gels without changing temperature, buffer composition, or other environmental conditions, apart from the application of DNA, makes these materials attractive candidates for biotechnology applications.

A new Mg–Cu–Ni–Ag–Zn–Y–Gd alloy with significantly improved glass forming ability (GFA) was developed in this work. Mg65Cu7.5Ni7.5Ag5Zn5Y5Gd5 bulk metallic glass (BMG) with a diameter of 14 mm was successfully fabricated by conventional copper mold casting method in air atmosphere. The critical cooling rate for glass formation was estimated to be about 20 K/s. When the maximum diameter for glass formation was compared with those previously reported for Mg-based alloys, the Mg65Cu7.5Ni7.5Ag5Zn5Y5Gd5 alloy showed the highest GFA. However, when the GFA was compared with those of Mg-TM-RE alloys (TM: Cu, Ni, Zn, and Ag; RE: Y and Gd), the significant improved GFA of the Mg–Cu–Ni–Zn–Ag–Y–Gd alloy cannot be properly represented by ΔTx, Trg, K, and γ parameters. In contrast to most of the Mg-based BMGs reported so far, the Mg65Cu7.5Ni7.5Ag5Zn5Y5Gd5 BMG exhibits yielding and plastic deformation during compressive loading.

An Fe-doped ZnO particle/polymer hybrid was synthesized from zinc acrylate (ZA) and iron allylacetylacetonate (IAA) using methylhydrazine. Nanocrystalline ZnO particles were formed in the organic matrix by hydrolysis and polymerization of ZA itself below 100 °C. The crystallinity of undoped ZnO particles in the hybrid was dependent upon the synthesis conditions. Similarly, the ZnO phase was observed for the product formed from ZA-IAA. Transmission electron microscopy and energy-dispersive x-ray analysis revealed that crystalline ZnO nanoparticles doped with Fe were dispersed in the organic matrix. The absorption edge of the undoped ZnO particle/polymer hybrid was blue-shifted with the decrease in size of the ZnO particles. On the other hand, the Fe-doped ZnO particle/polymer hybrid from ZA-IAA revealed a bathochromic shift of the absorption edge up to 600 nm.

A kinetics model based on mass and heat transport has been developed for Ti3SiC2 formation via shock-activated reaction synthesis of powder precursors. The model allows prediction of heat treatment conditions under which an otherwise steady-state reaction is taken over by a “run-away” combustion-type reaction during post-shock reaction synthesis of Ti3SiC2. Shock compression of Ti, SiC, and graphite precursors generates a densely packed highly activated state of reactants, which lowers the activation energy and results in an increased rate of formation of Ti3SiC2 at a lower temperature and in shorter times. The predictive model correlated with experimental results of fraction reacted as a function of time at heat-treatment temperatures of 1400 and 1600 °C illustrates an increased rate of reaction due to lowering activation energy, which also results in the reaction at 1600 °C being taken over by a “run-away” combustion-type reaction, as the rate of heat release due to reaction exceeds the rate of heat dissipation through the compact. Correlation of the model with experimental results illustrates that the predictive model can be used to optimize reaction synthesis conditions in shock-densified compacts of Ti3SiC2-forming powder precursors, to better understand the processes leading to a steady-state reaction being taken over by the combustion mode.

Nanocrystal n-diamond particles were synthesized after a pyrogenation of carbon nanotubes and colloidal Fe(OH)3 at atmospheric pressure. The product was investigated with x-ray diffraction, transmission electron microscopy, thermal gravimetric analysis, and differential thermal analysis. The results indicate that the n-diamond can be synthesized with the carbon nanotubes as carbon source. The formation mechanism of the n-diamond is suggested in this paper. With the increase of temperature and hence the carbon diffusion in iron, the phase sequence is from Fe(OH)3 into Fe2O3, α–Fe, γ–Fe, and then liquid iron. When carbon in the liquid iron is saturated, graphite separated out of the liquid iron. With the decrease of temperature, the carbon in γ–Fe is separated out, and the n-diamond nuclei form and grow.

The mechanical properties of thermally grown oxide films on various aluminum substrates were tested using nanoindentation. A sudden discontinuity, indicative of film fracture, was observed upon loading portion of the load–depth curve. The 63-nm-thick films were determined to have ultimate strengths between 4.8 and 8.9 GPa. The ultimate stress is a superposition of the bending and membrane stress. The stress intensity at fracture for each of the films was developed by approximating the resulting bending moment and various cracks sizes. At a constant ratio of crack size to oxide thickness of 0.3, the applied stress intensity at fracture of these aluminum oxide films were between 0.46 and 1.20 MPa m1/2. The residual stress in the film was assumed to be negligible in the stress intensity calculation.

In a previously developed method for estimating Young’s modulus E by depth-sensing indentation with spherical-tipped Berkovich indenter, the E value is deduced from several functional relationships (established by finite element analysis) relating nominal hardness/reduced elastic modulus ratio (Hn/Er) and elastic work/total work ratio (We/W). These relationships are specified for different absolute bluntness/maximum displacement ratios (Δh/hm). This paper reports the generalization of the method by proposing a function to replace all the above mentioned Hn/Er−We/W relationships. The function contains only a parameter Vr ≡ Videal/Vblunt instead of Δh/hm, where Videal is defined as the indented volume bounded by the cross-sectional areas measured at the maximum displacement hm for an ideally sharp indenter, and Vblunt is that of the real indenter. The use of Vr to replace Δh/hm is for the purpose of extending the application of the method for non-spherical tipped Berkovich indenters. The effectiveness of the method for materials of prominent plasticity was demonstrated by performing tests on carbon steel and aluminum alloy using three Berkovich indenters with different tip shapes.

Nano- and micrometer size spherical bismuth particles were prepared by reducing bismuth salts in simple and mixed polyols at elevated temperatures. In general, the conversion to metallic bismuth was preceded by the formation, at intermediate temperatures, of bismuth-polyol compounds. By changing the type of bismuth salt, the composition of the polyol mixture, and the temperature of the process, these precursors were successfully converted into spherical bismuth particles. It was found that the reduction process proceeds only if the temperature of the polyol exceeds the values at which the intermediate bismuth-polyol are stable, which was determined to be around 220 °C.