Three-dimensional image-based modeling is used to investigate the correlations between crystallographic orientation and mechanical response in a body-centered cubic (BCC) β-titanium microstructure. Statistical significance is achieved by combining the simulation data of multiple image-based crystal plasticity models. Each individual model contains ∼100 grains and is subjected to uniaxial and biaxial tensile loading conditions. Although the use of smaller sub-volumes instead of a single large representative volume may preclude accurate prediction of the global stress–strain response of the material, it is demonstrated here that the microstructural and mechanical information at the local (grain) scale can be used to establish statistically significant microstructure–property correlations. It is shown that grains with <100> orientations aligned with the loading axis experienced much smaller effective stresses and strains than those with <110> and <111> orientations aligned with the loading axis under both types of loading conditions.

The densification kinetics of a blend of unalloyed Ti and Al-40V master alloy powders are measured during uniaxial hot pressing under 3–10 MPa pressure for thermal cycling (860–1020 °C) or isothermal (1020 °C) conditions. Subsequent heat treatment for 4–16 h at 1020 °C results in a homogeneous Ti-6Al-4V microstructure. This process provides a low-cost alternative to hot isostatic pressing of prealloyed Ti-6Al-4V powders.

Herein we report a novel, environment-friendly approach for the reduction of graphene oxide by means of incorporating visible-light sensitive TiO2 and steady state visible-light irradiation. The surface morphology and fine structure of as-prepared composites were characterized by scanning electron microscopy and atomic force microscopy, respectively. The reduction process was evidenced by variation of conductivity. In addition, some of the electrochemical properties of the resultant graphene materials have been investigated as well.

Thermophysical properties such as phase-transformation temperatures and enthalpy of solidification depend on the composition and on the solidification conditions. To analyze the effects of the cooling rate on these properties, three commercial magnesium alloys (AZ91D, AM60B, and AE44) have been studied. Phase-transformation temperatures and enthalpy of solidification of these alloys have been measured using differential scanning calorimetry. Solidification curves have been obtained experimentally and compared with thermodynamic calculations. For all the studied alloys, it has been found that with increasing cooling rate, liquidus temperature increases slightly, whereas solidus temperature decreases. Enthalpy of solidification increases significantly with increasing cooling rate. Finally, relationships of phase-transformation temperature and enthalpy of solidification as a function of cooling rate have been established on the basis of the general power law. Using these relationships, the phase-transformation temperature and enthalpy of solidification have been predicted at high cooling rates and compared with experimental results.

Thermomigration in Pb-free SnAg solder alloys is investigated during accelerated electromigration tests under 9.7 × 103 A/cm2 at 150 °C. It is found that Cu–Sn intermetallic compounds (IMCs) migrate toward the cold end on the substrate side and, as a result, voids accumulate in the chip side for the bump with current flowing from the substrate end to the chip end. Theoretical calculations indicate that the thermomigration force is greater than the electromigration force at a thermal gradient above 400 °C/cm for this stressing condition. Copper atoms may migrate against current flow and become the dominant diffusion species. On the other hand, Ni–Sn IMCs did not migrate even under a huge thermal gradient of 1400 °C/cm. These findings provide more understanding on the thermomigration of metallization materials in flip-chip solder joints.

The optimum glass formers in ternary La-TM-Al (TM = Co, Ni, Cu) alloys were pinpointed at alloys La69Co17Al14, La66Ni19Al15, and La66Cu20Al14, exhibiting critical sizes for full glass formation of 16, 12, and 5 mm, respectively. Cobalt is found to be the most favorable element for glass formation in La-based alloys. The optimum alloys in La-TM-Al show close composition but significantly different glass-forming ability (GFA). The mechanism of distinct effect of TM elements remains unclear, even discussed based on current GFA-related criteria and indicators.

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.

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.

Oxygen vacancy-related surface defects on porous TiO2 films were reduced by oxygen ion-beam treatment, and the effect of such defects on the performance of dye-sensitized solar cells was examined. An oxygen ion-beam treatment of a TiO2 film caused a significant decrease in particle agglomeration and an increase in surface area of the resulting TiO2 film. In addition, the increased hydrophilicity of the TiO2 film by the ion beam treatment led to an increase in dye adsorption. The oxygen ion beam treatment at 500 and 1000 eV caused a significant decrease in oxygen vacancies and increase in the open-circuit voltage (Voc). Oxygen ion beam–treated TiO2 film electrodes showed the maximum solar-to-electricity conversion efficiency (η%) of 8.04% compared to the 6.15% obtained from an untreated TiO2 electrode.

The development of novel organic polymer thin films is essential for the advancement of many emerging fields including organic electronics and biomedical coatings. In this study, the effect of synthesis conditions, namely radio frequency (rf) deposition power, on the material properties of polyterpenol thin films derived from nonsynthetic environmentally friendly monomer was investigated. At lower deposition powers, the polyterpenol films preserved more of the original monomer constituents, such as hydroxy functional groups; however, they were also softer and more hydrophilic compared to polymers fabricated at higher power. Enhanced monomer fragmentation and consequent reduction in the presence of the polar groups in the structure of the high-power samples reduced their optical band gap value from 2.95 eV for 10 W to 2.64 eV for 100 W. Regardless of deposition power, all samples were found to be optically transparent with smooth, defect-free, and homogenous surfaces.

There are many challenges associated with adapting traditional nanoindentation methods to the study of compliant, hydrated biomaterials. These include issues related to surface detection, tip–sample adhesion, and fluid interactions. This study demonstrates that the nano-Johnson–Kendall–Roberts (JKR) force curve method can be used effectively in both air and water to overcome the challenges of surface detection and adhesion for nanoindentation of a compliant polymer. Indents were performed on poly(dimethyl siloxane) samples in air, water, and a detergent solution, with detergent used to reduce interfacial forces and provide baseline modulus measurements. The results demonstrated that errors due to adhesion dominated errors due to surface detection or fluid interactions and that JKR modeling could compensate for errors due to adhesion. Several JKR curve-fitting techniques were also evaluated, and all were found to result in moduli within 10% of the baseline moduli of the materials, demonstrating the robustness of this technique.

It was observed that the cement line (CL), namely the border of the osteon in cortical bone, plays an important role in bone fracture: arresting and deflecting cracks. The underlying mechanism was speculated to be that each CL behaves as a weak interface, and thus, it attracts and deflects the bone cracks due to the debonding at the CL. This speculation of a weak CL has not been experimentally verified due to the CL’s challengingly small width. In this study, nanoindentation arrays were carefully conducted to characterize the CLs in ovine and bovine femurs. We found that the modulus and hardness of the CLs are about 30% less than those of the surrounding bone tissues in both species. Thus, for the first time, we characterized the mechanical properties of the CL and verified the speculation of a weak CL, providing a quantitative/constitutive basis for the theoretical modeling of bone micromechanics involving the CL.

Silicon oxide has been widely used to encapsulate biomolecules to preserve their activity in less than ideal environments. However, there are other inorganic oxides with inherent properties that would be advantageous in creating a multifunctional material. Titanium oxide exhibits properties that have applications in areas such as electronics, energy conversion, and decontamination. Herein is reported the formation of titania coatings fabricated on polymer beads using a biomimetic approach and characterized with scanning electron microscopy and energy dispersive x-ray spectroscopy. The approach involves the use of functionalized polymer beads, which initiate oxide formation from a water-soluble titanium complex. The method was used to encapsulate the enzyme diisopropylfluorophosphatase, in situ, within the oxide matrix under buffered aqueous conditions while retaining its enzymatic activity against diisopropylfluorophosphate. In addition, the biomimetically produced titania was shown to exhibit UV-assisted degradation activity against an ethidium bromide dye, upon liberation from the coating template.

A facile and efficient, one step method using high-energy ball milling (HEBM) to produce chloroalkyl-functionalized silicon nanoparticles is described. HEBM causes silicon wafers to fracture and exposes reactive silicon surfaces. Nanometer-sized, functionalized particles with alkyl-linked chloro groups are synthesized by milling the silicon precursor in presence of an ω-chloroalkyne in either hexene or hexyne. This process allows tuning of the concentration of the exposed, alkyl-linked chloro groups, simply by varying the relative amounts of the coreactants. The silicon nanoparticles formed serve as a starting point for a wide variety of chemical reactions, which may be used to alter the surface properties of the functionalized nanoparticles.