Evolution of deformation texture in commercially pure titanium with submicron grain size (SMG) was studied using x-ray diffraction (XRD) and electron back scatter diffraction (EBSD) methods. The material was deformed by rolling at room temperature. The deformation mechanism was found to be slip dominated with a pyramidal <c + a> slip system facilitating plastic deformation. No evidence of tensile or compressive twinning was detected, as generally seen in the case of titanium with conventional microcrystalline grain size. The absence of twinning and the propensity of the pyramidal <c + a> slip system in the SMG Ti is attributed to the lack of coordinated motion of zonal partial dislocations that leads to twinning.

We propose a phenomenological Landau theory to describe polymorphic melting in binary solid solutions. We use the mean atomic displacement as the primary order parameter to represent the loss of the long-range order and the elastic strain induced by alloy component as the secondary order parameter. Under polymorphic constraint where alloy concentration fluctuation is restricted, the model predicts the melting line, also called T0-curve that is depressed by two factors, the static strain field caused by the solute, and the anharmonicity induced by the thermal vibration. We also obtain other thermodynamic properties at and around the melting point. The results confirm well with available experimental results for dilute solutions. We extrapolate the melting line to high concentration region for which no experimental data are available. From the results, we discuss the relation between polymorphic melting and glass transition, as well as glass formability.

Both low and high resistance states (which were written by voltage application in a local region of NiO/Pt films using conducting atomic force microscopy [C-AFM]) were observed with scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The writing regions are distinguishable as dark areas in a secondary electron image and thus can be specified without using a complicated sample fabrication process to narrow down the writing regions such as the photolithography technique. In addition, the writing regions were analyzed using energy-dispersive x-ray spectroscopy (EDS) mapping. No difference between the inside and outside of the writing regions is observed for all the mapped elements including C and Rh. Here, C and Rh are the most probable candidates for contamination that affect the secondary electron image. Therefore, our results suggested that the observed change in the contrast of the secondary electron image is related to the intrinsic change in the electronic state of the NiO film and a secondary electron yield is correlated to the physical properties of the film.

Effects of stacking fault energy (SFE) on the thermal stability and mechanical properties of nanostructured (NS) Cu–Al alloys during thermal annealing were investigated in this study. Compared with NS Cu–5at.%Al alloy with the higher SFE, NS Cu–8at.%Al alloy exhibits the lower critical temperatures for the initiation of recrystallization and the transition from recovery-dominated to recrystallization-dominated process, which significantly signals its low thermal stability. This may be attributed to the large microstructural heterogeneities resulting from severe plastic deformation. With increasing the annealing temperatures, both Cu–Al alloys present the similar trend of decreased strength and improved ductility. Meanwhile, the remarkable enhancement of uniform elongation is achieved when the volume fraction of Static recrystallization (SRX) grains exceeds ~80%. Moreover, the better strength–ductility combination was achieved in the Cu–8at.%Al alloy with lower SFE.

Amorphous ribbons of (Fe1-xCox)88Zr7B4Cu1 (x = 0.2, 0.35, 0.5, and 0.6) alloys were annealed to produce a nanocrystalline phase dispersed in the amorphous matrix. Precision lattice parameter calculation showed that composition of the nanocrystalline phase is Fe73Co27 for all the alloys irrespective of initial alloy composition. This result was well corroborated with the Mössbauer results. Saturation magnetization of annealed ribbons was almost same for all the alloys, however, coercivity increases with Co content.

Locally Er3+-doped noncongruent, Li-deficient Ti:Er:LiNbO3 strip waveguide was fabricated with a technological process in sequence of preparation of Li-deficient LiNbO3 substrate using Li-poor vapor transport equilibration (VTE), Er3+, and Ti4+ diffusion in wet O2. The Li2O content change was evaluated from the measured birefringence. The Ti4+ and Er3+ profile characteristics in the waveguide were studied by secondary ion mass spectrometry. The results show that the VTE and subsequent Er3+ diffusion procedures resulted in totally ∼0.8 mol% Li2O content reduction. The Ti4+ profile follows a sum of two error functions in the width direction and a Gaussian function in the depth direction of waveguide. The Er3+ profile follows also a Gaussian function. At 1130 °C, the Ti4+ surface/depth diffusivity and surface concentration are 8.5 ± 1.3/1.98 ± 0.06 μm2/h and ∼7 mol%, respectively, and the Er3+ diffusivity and surface concentration are (12.8 ± 0.3) × 10−2 μm2/h and ∼0.6 mol%, respectively.

Graphene oxide nanoplatelets (GONPs) were obtained by unraveling helical-ribbon carbon nanofibers (HR-CNF) using a modified Hummers and Offeman method in conjunction with ultrasonication. In this account, we carry out a complete evaluation of the effect of different oxidative agent concentrations on the resulting platelet materials. Transmission electron microscopy, atomic force microscopy, Fourier transform infrared, x-ray diffraction, x-ray photoelectron spectroscopy, and thermogravimetric analysis were performed to carefully characterize GONPs resulting from the oxidative process. Comparative experiments using multiwall carbon nanotubes (MWCNTs) and graphite were also carried out. Our studies suggest that the oxidation treatment is more effective in HR-CNFs than in MWCNTs. Furthermore, the unraveling of HR-CNFs results in GONPs consisting of less stacked layers when compared to other starting materials such as graphite. Therefore, HR-CNFs appear to be excellent precursors to produce few-layered GONPs.

The compositional dependence of phase formation, thermal stability, and mechanical properties of (Cu0.5Zr0.5)100−x(Al0.5Ag0.5)x (x = 2, 4, 6, 8, 10, 12, 14, 16) bulk metallic glasses was studied. The Young’s modulus (85 ± 1 to 95 ± 1 GPa) and Vicker’s hardness (585 ± 7 to 627 ± 8 Hv) increased with increasing Al + Ag content from 8 to 16 at.%, respectively. The liquidus temperature decreased from 1210 ± 2 to 1110 ± 2 K with increasing Al + Ag content from 2 to 16 at.%. The starting temperature of the endothermic event related with transformation of the low-temperature equilibrium phases to CuZr parent phase increased from 997 ± 2 to 1043 ± 2 K, whereas the electronegativity difference for the (Cu0.5Zr0.5)100−x(Al0.5Ag0.5)x (x = 2, 4, 6, 8, 10, 12) alloys decreased from 0.2838 to 0.2713. The martensitic transformation temperatures decreased with increasing Al and Ag content for the (Cu0.5Zr0.5)100−x(Al0.5Ag0.5)x (x = 2, 4, 6, 8) alloys.

In a 2.25Cr1.5W heat-resistant alloy, it is shown that the time to intergranular failure under tensile stress t can be expressed by , where t0 is the constant of proportionality, n is the stress exponent, and Q is the activation enthalpy. It is shown that the dimples observed at elevated-temperature intergranular fracture surfaces are not the micro-ductile fracture areas but the interfaces between the grain boundary carbides and the neighboring grains. It is also shown that the segregation concentration of solute atoms is much higher at the grain boundary carbide interfaces than at the carbide-free grain boundaries. Under tensile stress, the elevated-temperature intergranular cracking occurs through the decohesion of grain boundary carbide interfaces, which is followed by the eventual carbide-free grain boundary cracking.

Flake-like Fe particles with controllable size and structures were achieved by modulating only the grinding speed; evidence provided by x-ray diffraction, scanning electron microscopy, resistivity measurement system, and vector network analyzer disclosed the conductivity; and microwave electromagnetic (EM) and absorbing characteristics of the resultant products strongly depended on their morphology and structure. As grinding speed (V) increases from 0 to 250 revolutions per minute (rpm), the crystalline size decreases; meanwhile, both internal strain and diameter/thickness ratio increase and the conductivity reaches the maximal value at V = 140 rpm because of the improvement of the surface conductivity. Thin flake-like Fe particles facilely obtained at high grinding speed present higher values of the permittivity and permeability than spherical particles, which are ascribed to the multiple polarizations and the natural resonance. Thus, the aforementioned products with high permeability and low cost may be promising candidates for EM compatibility materials.

Depending on the Ni:Co molar ratio, composites of NiCo/carbon nanorods and NiCo/carbon nanotubes can be synthesized through catalytic decomposition of benzene at 500 °C over NiCo nanoparticles derived from sol–gel synthesis followed by hydrogen reduction. According to x-ray diffraction results, the average grain size of NiCo31 is 11.2 nm, whereas that of NiCo13 and NiCo22 is 24.9 nm. Field-emission scanning electron microscopic and high-resolution transmission electron microscopic images reveal that over NiCo13 and NiCo22, the carbon nanomaterials are mainly in the form of nanorods, whereas over NiCo31, they are in the form of nanotubes. The composites of carbon and NiCo alloy are highly stable in air and show soft magnetic property and almost equal coercivity. It is observed that the saturation magnetization is affected by the composition of NiCo alloy.

This article reports on the role of annealing on the development of microstructure and its concomitant effects on the thermoelectric properties of polycrystalline AgPbmSbTe2+m (m = 18, lead–antimony–silver–tellurium, LAST-18) compounds. The annealing temperature was varied by applying a gradient annealing method, where a 40-mm-long sample rod was heat treated in an axial temperature gradient spanning between 200 and 600 °C for 7 days. Transmission electron microscopy investigations revealed Ag2Te nanoparticles at a size of 20–250 nm in the matrix. A remarkable reduction in the thermal conductivity to as low as 0.8 W/mK was also recorded. The low thermal conductivity coupled with a large Seebeck coefficient of ∼320 μV/K led to high ZT of about 1.05 at 425 °C for the sample annealed at 505 °C. These results also demonstrate that samples annealed above 450 °C for long term are more thermally stable than those treated at lower temperatures.

Diffusion of interstitial hydrogen atoms in α-iron was investigated using molecular dynamic simulation. In particular, hydrogen diffusivities in bulk, on (001) surface and within a Σ5 [100]/(013) symmetric tilt grain boundary (STGB) were estimated in a temperature range of 400 and 700 K. Furthermore, hydrogen diffusivities in a series of Σ5 [100] tilt grain boundaries with different inclinations were also determined as a function of temperature. The inclination dependence of activation energy for diffusion exhibits two local maxima, which correspond to two STGBs. Additional calculation of inclination dependence of boundary energy and boundary specific excess volume shows two local minima at the same STGBs. This suggests hydrogen diffusion into and within a grain boundary might be assisted by grain boundary excess volume and stress. Simulation of effects of hydrostatic pressure on diffusion shows tensile stress can promote hydrogen diffusion in lattice into grain boundary or surface traps, while compressive stress leads to a decrease in diffusivity, and a slower rate of filling these traps.

In this work, a visible-light-sensitized neodymium complex with 2-(N,N-diethylanilin-4-yl)-4,6-bis(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine (Dpbt) as a synergetic ligand is synthesized and incorporated into poly(methyl methacrylate) (PMMA). Absorption and luminescent spectra of Nd(TTA)3Dpbt (TTA = thenoyltrifluoroacetonate) in PMMA are measured and compared with common complex Nd(TTA)3Phen (Phen = 1,10-phenanthroline). As a result, Nd(TTA)3Dpbt has relatively high luminescent intensity and wide excited spectral range, attributed to the sensitization of the ligand Dpbt. Judd–Ofelt analysis is used, and Judd–Ofelt parameters are calculated (Ω2 = 33.72 × 10−20 cm2, Ω4 = 11.52 × 10−20 cm2, and Ω6 = 6.81 × 10−20 cm2). The radiative properties are predicted and compared with other different Nd complexes. The stimulated emission cross-section of 4F3/2→4I11/2 transition is 3.02 × 10−20 cm2 and the estimated lifetime is 506 μs using the Judd–Ofelt parameters. Experimental fluorescence branching ratio of this transition is quite high for Nd ions. The radiative properties’ investigation for 4F3/2→4I11/2 transition indicates that it is possible to be a laser transition.

Technological progress in the synthesis and characterization of nanometer-scale structures has improved understanding of molecular and colloidal aggregation, self-assembly, and crystal growth. While substrates are commonly used to control nucleation and growth in metal and semiconductor crystals, their use in protein epitaxy has been limited by the lack of substrate structures commensurate with protein sizes. In this paper we describe the use of polished cross sections of amorphous alumina–silica nanolaminates whose periods varied from 8 to 200 nm in the formation of self-assembled monolayers of the protein macromolecule aspartate transcarbamoylase (ATCase). Scanning force microscopy images of rapidly deposited ATCase demonstrates one-dimensional protein ordering along 13.5 nm wide silica nanolaminate. Numerical studies of irreversible adhesion indicate that patterning can induce a higher degree of ordering by varying the substrate periodicity. We expect this to have implications for nucleation and growth of both two-dimensional crystalline layers and bulk protein crystals.

In this work, the silk fibroin/sericin (SF/SS) blend aqueous solutions with different SF/SS mass ratios (100/0, 90/10, 85/15, 75/25, and 65/35) were prepared and electrospun to get regenerated fibers. It was found that the addition of SS in the SF solution could increase the apparent viscosity of the solution and improve its electrospinnability so that the fine uniform electrospun SF/SS fibers could be obtained. The quantitative analysis result of Raman spectroscopy showed that the presence of SS facilitated the conformational transition of SF from random coil/α-helix structure to β-sheet structure. Combined with the differential scanning calorimetry result, it was further hypothesized that SS could affect the structural change of SF by dehydrating SF and inducing the formation of hydrogen bonds between SF molecules. Consequently, SS also played an important and positive role in the thermal and mechanical properties of the resultant SF/SS fibers.

Effects of tungsten (W) addition to the electroless Ni(P) under bump metallization (UBM) on the solder joint reliability were investigated by preparing Ni–xW–5P and Ni–xW–9P films. Characteristics of the NiWP films, interfacial reaction with Sn–3.5Ag solder, and the impact resistance of solder joints was investigated by conducting differential scanning calorimetry, x-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), and drop tests. Tungsten increased the thermal stability of the film and raised the crystallization temperature, but the crystallinity decreased with the W content in the film. The drop impact resistance of the Sn–3.5Ag/Ni–xW–9P joints was improved remarkably with the W content in the UBM, which was a direct consequence of the elimination of Ni3Sn4 spalling from the UBM. Additions of W up to 16 wt.% did not suppress intermetallic compound (IMC) spalling completely, but 22 wt.% W did up to 4 reflows, which increased the number of drops to failure (Nf) from 50 to over 300. TEM study showed the presence of an amorphous (Ni,W)3P layer between Ni3Sn4 and the original Ni–22W–9P UBM.

This study investigated a fundamental aspect of thermoelastic martensitic transformations in different shape memory alloys by means of interrupted thermal analysis technique using differential scanning calorimetry (DSC). The objective of this study was to determine the true transformation temperature interval. It also provides the opportunity to further the discussion of time dependence of the transformations. The study applied a technique of thermal arrest amidst phase transformations. The transformation temperature intervals were found to be 8.4 and 12.9 K for the forward and reverse B2↔B19′ martensitic transformation in a near-equiatomic Ti-50.2 at.% Ni alloy and 14.7 and 12.8 K in a Ni-rich Ti-50.8 at.% Ni alloy and 7.3 and 9.1 K for the L21↔orthorhombic transformation in a Ni43Co7Mn39In11 alloy. These values were significantly smaller than those commonly reported in the literature. The experimental evidences also demonstrated that the apparent time dependences of the martensitic transformations manifested in DSC analysis were artifacts caused by instrumental thermal inertia.

A gradient structure was synthesized on the surface of Zr55Al10Ni5Cu30 alloy with high glass-forming ability by laser surface melting (LSM). Along the laser incident direction, the surface remelted alloy exhibits gradient microstructure distributed in the sequence of amorphous structure, nanocrystal- reinforced amorphous matrix composite (transitional layer A), dendrites–amorphous phase composite (transitional layer B), and crystalline phases from the top surface to the substrate. The formation mechanism of this gradient structure is discussed based on the experimental results of the microstructure together with the finite volume simulation of the process of LSM treatment. The friction coefficient of the transitional layer A is ∼2.5 times lower than those of the other layers under the same sliding friction condition, and possible reasons for this phenomenon are discussed in connection with the rolling motion and material transfer mechanism. The transitional layer B exhibits the best wear resistance among all the structures studied here, which is related to the optimized ratio of microhardness to reduced Young’s modulus (H/Er).

The growth kinetics of Si bulk crystals and nanowires (NWs) in contact with Au–Si liquids is studied by molecular dynamics simulations using an empirical potential fitted to the Au–Si binary phase diagram. The growth speed v is predicted as a function of Si concentration xSi in the Au–Si liquid at temperature T = 1100 K and as a function of T at xSi = 75%. For both bulk crystals and NWs, the {111} surface grows by the nucleation and expansion of a single two-dimensional island at small supersaturations, whereas the {110} surface grows simultaneously at multiple sites. The top surfaces of the NWs are found to be curved near the edges. The difference in the growth velocity between NWs and bulk crystals can be explained by the shift of the liquidus curve for NWs. For both bulk crystals and NWs, the growth speed diminishes in the low temperature limit because of reduced diffusivity.