The structure of hypoeutectic, hypereutectic, and eutectic Ti–Fe alloys produced in the shape of arc-melted ingots was found to consist of the ordered Pm-3m TiFe and disordered BCC Im3m β–Ti solid solution phase. The dimensions of the ingots were about 25–40 mm in diameter and 10–15 mm in height, and their structure was studied by x-ray diffractometry and scanning electron microscopy. The rectangular parallelepiped-shaped samples 2.5 × 2.5 × 5 mm in size cut from the central part of the ingots exhibit a high strength of about 2000 MPa, except for Ti60Fe40, and a certain ductility. The relatively low density of Ti (4.5 Mg/m3) implies high strength/density ratio for the studied alloys. These alloys are characterized by the low cost of the alloying element Fe and, compared to most of the high-strength non-equilibrium materials, do not require additional injection mold casting or rapid solidification procedures.

Separation by implemented oxygen (SIMOX)(111) substrates have been formed by oxygen-ion (16O+) implantation into Si(111), showing that a so-called “dose-window” at 16O+-implantation into Si differs from Si(100) to Si(111). In SIMOX(100), an oxygen dose of 4 × 1017/cm2 into Si(100) is widely recognized as the dose-window when the acceleration energy is 180 keV. For the first time, our work shows that an oxygen dose of 5 × 1017/cm2 into Si(111) is the dose-window for the formation of SIMOX(111) substrates when the acceleration energy is 180 keV. The difference between dose-windows is caused by anisotropy of the crystal orientation during growth of the faceted buried SiO2. We also numerically analyzed the data at different oxidation velocities for each facet of the polyhedral SiO2 islands. Numerical analysis results show good agreement with the experimental data.

The structures of the defect perovskite Pb1−3/2xLaxTiO3 prepared by the solid-state method were investigated in the solubility range of 0.05 ⩽ x ⩽ 0.30 with 0.05 increment by x-ray Rietveld method. In the system Pb1−3/2xLaxTiO3, the atom displacements of Ti (δTi) and Pb/La (δPb/La) along the spontaneous polarization (Ps) direction (c axis) decrease nonlinearly with increasing La content, while the value of δTi/δPb/La decreases linearly. The shape of oxygen octahedron of compounds Pb1−3/2xLaxTiO3 is independent of the La content. The calculated value of Ps decreases linearly in the solubility range of 0.05 ⩽ x ⩽ 0.30. In the refinement process, the hkl dependence of diffraction line broadening was also taken into account. The anisotropy of microstrain-like broadening observed in Pb1−3/2xLaxTiO3 might be ascribed to occurrence of compositional inhomogeneity between the crystallites.

We report the growth of epitaxial nanowire arrays using the technique of glancing- angle deposition with substrate rotation. Epitaxial copper nanowire arrays were deposited on H-terminated Si(110) using electron beam evaporation. The nanowire arrays were characterized by x-ray diffraction, atomic force microscopy, and scanning electron microscopy. Individual nanowires were confirmed to be single crystalline by examination with transmission electron microscopy. The epitaxial growth involves twin formation with the epitaxial orientation relationships: Cu(111)//Si(110) with Cu[110]//Si[001] and Cu[110//Si[001] for each of the twins. As the angle of incidence is increased, Cu grows as isolated columns with a spacing that increases as the angle of incidence is increased. However, the thickness limit for epitaxial growth is reduced as the angle of incidence is increased, and it is reduced to approximately 300 nm for a deposition angle of 75°. The x-ray rocking curves for samples deposited at increasing polar angles show steadily improving crystal orientation up to a deposition angle of about 35°. Beyond 65° deposition angle, the rocking curves show significantly sharper split diffraction peaks indicating that there are distinct orientations. In addition, the split peaks have a much lower full width at half maximum. The observed behavior is explained based on arguments involving unidirectional diffusion arising from adatom parallel momentum.

Dislocation–interface interactions in Fe–0.4 wt% C tempered martensitic steel were studied through in situ nanoindentation in a transmission electron microscope (TEM). Two types of boundaries were imaged in the dislocated martensitic structure: a low-angle (probable) lath boundary and a coherent, high-angle (probable) block boundary. In the case of a low-angle grain boundary, the dislocations induced by the indenter piled up against the boundary. As the indenter penetrated further, a critical stress appeared to have been reached, and a high density of dislocations was suddenly emitted on the far side of the grain boundary into the adjacent grain. In the case of the high-angle grain boundary, the numerous dislocations that were produced by the indentation were simply absorbed into the boundary, with no indication of pileup or the transmission of strain. This surprising observation is interpreted on the basis of the crystallography of the block boundary.

The creep behaviors of 20 vol% SiCw/2124Al, extruded with different ratios, and SiCp/2124Al, reinforced with 10–30 vol% SiC particles, were investigated to clarify the effects of aspect ratio, alignment, and volume fraction of reinforcement on creep deformation. The effective stresses on the matrix of SiC/Al composites are calculated based on the generalized shear-lag model. The minimum creep rates of SiCw/2124Al extruded with different ratios and SiCp/2124Al reinforced with different volume fractions of SiC particles are found to be similar under a same effective stress on matrix, which is calculated by the generalized shear-lag model. The subgrain sizes in matrices of crept SiC/Al composites are dependent on the effective stress on matrix but not on the applied stress on the composite. It is suggested that the role of SiC reinforcements is to increase the creep resistance of SiC/Al composite by reducing the effective stress on matrix.

A finite element analysis of frictionless indentation of an elastic–plastic half-space by a rigid sphere is presented and the deformation behavior during loading and unloading is examined in terms of the interference and elastic–plastic material properties. The analysis yields dimensionless constitutive relationships for the normal load, contact area, and mean contact pressure during loading for a wide range of material properties and interference ranging from the inception of yielding to the initiation of fully plastic deformation. The boundaries between elastic, elastic–plastic, and fully plastic deformation regimes are determined in terms of the interference, mean contact pressure, and reduced elastic modulus-to-yield strength ratio. Relationships for the hardness and associated interference versus elastic–plastic material properties and truncated contact radius are introduced, and the shape of the plastic zone and maximum equivalent plastic strain are interpreted in light of finite element results. The unloading response is examined to evaluate the validity of basic assumptions in traditional indentation approaches used to measure the hardness and reduced elastic modulus of materials. It is shown that knowledge of the deformation behavior under both loading and unloading conditions is essential for accurate determination of the true hardness and reduced elastic modulus. An iterative approach for determining the reduced elastic modulus, yield strength, and hardness from indentation experiments and finite element solutions is proposed as an alternative to the traditional method.

While the dimension of solder bumps keeps shrinking to meet higher performance requirements, the formation of interfacial compounds may be affected more profoundly by the other side of metallization layer due to a smaller bump height. In this study, cross interactions on the formation of intermetallic compounds (IMCs) were investigated in eutectic SnPb, SnAg3.5, SnAg3.8Cu0.7, and SnSb5 solders jointed to Cu/Cr–Cu/Ti on the chip side and Au/Ni metallization on the substrate side. It is found that the Cu atoms on the chip side diffused to the substrate side to form (Cux,Ni1−x)6Sn5 or (Niy,Cu1−y)3Sn4 for the four solders during the reflow for joining flip chip packages. For the SnPb solder, Au atoms were observed on the chip side after the reflow, yet few Ni atoms were detected on the chip side. In addition, for SnAg3.5 and SnSn5 solders, the Ni atoms on the substrate side migrated to the chip side during the reflow to change binary Cu6Sn5 into ternary (Cux,Ni1−x)6Sn5 IMCs, in which the Ni weighed approximately 21%. Furthermore, it is intriguing that no Ni atoms were detected on the chip side of the SnAg3.8Cu0.7 joint. The possible driving forces responsible for the diffusion of Au, Ni, and Cu atoms are discussed in this paper.

Single crystalline nanorods (15–200 nm in diameter and hundreds nanometers in length) have been formed on the carbon-covered W wires by simple electric heating under a vacuum of 5 × 10−4 Pa. The chemical composition and crystalline structure of the nanorods were carefully investigated by various characterization techniques such as scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, energy dispersive x-ray spectroscopy and electron energy loss spectroscopy. After ruling out any possible existence of carbon nanotubes (CNTs), tungsten carbide, W–Fe alloying, and formation of other types of tungsten oxides, monoclinic W18O49 phase has been well identified. The mechanism of nanorod formation of sub-tungsten oxide (∼WO2.7 compared to WO3) will be discussed in relation to the sample preparation conditions.

Highly oriented Pb(Zr,Ti)O3 (PZT) films were deposited on Pt/Ti/SiO2/Si substrates by the sol-gel method using lanthanum nitrate as a buffer layer. When the lanthanum nitrate buffer layer was heat treated at temperatures between 450 and 550 °C, the PZT layer coated onto this buffer layer showed a strong (100) preferred orientation. Regardless of the other deposition conditions, such as the pyrolysis temperature, pyrolysis time, annealing temperature and heating rate, the film deposited on the buffer layer had this orientation. Thick films were also fabricated using the sol-gel multi-coating method, and the (100) texture was found to be maintained up to a thickness of 10 μm. The ferroelectric hysteresis and piezoelectric coefficient (d33) of highly oriented PZT thick films were characterized, and the (100) oriented PZT film showed higher piezoelectric property than the (111) oriented film.

Molecular dynamics simulations of intergranular films (IGFs) containing Si, O, N, and Ca in contact with three different types of surface terminations of Si3N4 were performed using a multi-body interatomic potential. IGFs with the same Ca concentration (12 mol% CaO) but different nitrogen concentrations [N/(N + O) = 0, 15, 30, and 50%] were studied. In all 12 IGFs, Ca ions did not compete with the first adsorbed layer of Si at the IGF/basal crystal interface, but did so at the IGF/prism crystal interface. The simulations show the epitaxial adsorption of Si, O, and N from the IGF onto the basal and prism crystal surfaces. While more adsorbed N was expected as nitrogen concentration increases, there was a significantly larger amount of N adsorbed to the basal surface than to the prism surface. It was found that Ca ions sit closer to the prism surface than the basal surface but move closer to the crystal at both surfaces with increasing nitrogen concentration, although the effect was more pronounced at the basal interface. With the increase of nitrogen concentration, the percentage of two-coordinated oxygen remained about the same, but there was a change in the type of defect oxygen present. In all the simulations, the central position of the first peak in the Si–O pair distribution fixation (PDF) ranges from 1.63 to 1.65 Å, and that of Si–N PDF ranges from 1.71 to 1.73 Å, both consistent with experimental findings. Furthermore, the first peak of both the Si–O and Si-N PDF shifts to larger values as the nitrogen concentration increases, indicating the elongation of the Si–O and Si–N bond in the IGF with the increase of nitrogen concentration. Elongation of both the Si–N and Si–O bonds could lead to weakening of the IGF as nitrogen concentration increases, although competing changes in bonding of the O complicate the effect of N addition on the strength of the IGF.

The goal of this study was to demonstrate that a relationship exists between surface stress and pitting corrosion. The surface stress field generated by polishing was first calculated using a thermomechanical model and a finite element code. Pitting corrosion tests performed at the microscale along the austenite/ferrite interface using the electrochemical microcell technique were then analyzed considering the microstructure, and the residual surface stress field calculated numerically under the microcapillary. Mechanical criteria are proposed leading to an enhancement of pitting corrosion of duplex steels.

FeCoNi ternary alloy nanowire arrays 32–106 nm in diameter were fabricated within nanoporous alumina membranes using 15 Vrms alternating current electrodeposition at frequencies of 50, 250, 500, 750, and 1000 Hz. The magnetic coercivity and hysteresis loop squareness-ratio (Mr/Ms) were studied as functions of electrolyte composition, nanowire diameter, and nanowire aspect ratio.

The use of an analytical approach to determine the relation between hardness and yield strength for materials with a high ratio of yield strength to Young's modulus is re-examined. It is shown that predictions using the analogy of the spherical cavity fail to reproduce experimental and finite element results because the surface deflection that occurs during loading is not taken into account. A modification is proposed to allow this. This gives a greatly improved prediction of the relationship between the hardness and yield strength of a material. It also enables the effect of the indenter shape on the measured hardness to be incorporated and explains why in some very hard materials, indentation is observed to be completely elastic.

After this article appeared in the September 2004 issue of Journal of Materials Research, the authors noticed that the y2-axis labels for Fig. 1 were printed incorrectly. The correct figure is shown below: