In the present study, pure titanium (Ti) plates were firstly treated to form various types of oxide layers on the surface and then were immersed into simulated body fluid (SBF) to evaluate the apatite-forming ability. The surface morphology and roughness of the different oxide layers were measured by atomic force microscopy (AFM), and the surface energies were determined based on the Owens–Wendt (OW) methods. It was found that Ti samples after alkali heat (AH) treatment achieved the best apatite formation after soaking in SBF for three weeks, compared with those without treatment, thermal or H2O2 oxidation. Furthermore, contact angle measurement revealed that the oxide layer on the alkali heat treated Ti samples possessed the highest surface energy. The results indicate that the apatite-inducing ability of a titanium oxide layer links to its surface energy. Apatite nucleation is easier on a surface with a higher surface energy.

The molecular dynamics method has been used to simulate mode I cracking in Ni3Al. Close attention has been paid to the process of atomic configuration evolution of the cracks. The simulation results show that at low temperature, the Shockley partial dislocations are emitted before the initiation of the crack propagation, subsequently forming the pseudo-twins on (111) planes in crack-tip zone, and then the crack cleavage occurs. The emitting of the Shockley partial dislocations accompanies the crack cleavage during the simulation process. At the higher temperature, the blunting at the crack tip is caused by the [110] superdislocations emitted on (100) plane. The present work also shows that the dipole dislocations on (111) planes in the 1/2[110] dislocation core can be formed.

This article first provides a brief review of the status of the subfield of three-dimensional (3D) materials analyses that combine serial sectioning, electron backscatter diffraction (EBSD), and finite element modeling (FEM) of materials microstructures, with emphasis on initial investigations and how they led to the current state of this research area. The discussions focus on studies of the mechanical properties of polycrystalline materials where 3D reconstructions of the microstructure—including crystallographic orientation information—are used as input into image-based 3D FEM simulations. The authors' recent work on a β-stabilized Ti alloy is utilized for specific examples to illustrate the capabilities of these experimental and modeling techniques, the challenges and the solutions associated with these methods, and the types of results and analyses that can be obtained by the close integration of experiments and simulations.

Structures containing stacked layers of silicon-rich silicon nitride (green-blue luminescence) and oxide (red luminescence) fabricated by ion implantation are reported, and it is shown how a Si-based material can be engineered to emit over a broad range. To study in depth the emission from implanted SiNx matrices, single nitride layers have been also fabricated by the first time. Si excess variation and the relative thickness of nitride and oxide provide the intensity and position variation of the peaks, and thus open the way to engineer a stack with desired emission properties over the whole visible spectrum.

Luminescence properties of Yb-doped Ca-α-SiAlON phosphors with composition of Ca1−xYbxSi12−(m+n)Alm+nOnN16−n were investigated by using cathodoluminescence (CL). The ratio of Yb to Ca was kept constant while the host lattice was changed by replacing m+n(Si–N) bonds with m(Al–N) and n(Al–O) bonds. The luminescence of these phosphors consists of three peaks in the ultraviolet (UV), green (VIS), and infrared (IR) regions, which are attributed to the emissions from secondary phases, Yb2+ and Yb3+, respectively. The UV emission depends on the Si/Al ratio: the UV peak is centered at 310 nm for the Si-rich mix and at 360 nm for the Al-rich mix. We have found that Yb exists in the divalent state in α-SiAlON and in the trivalent state in the secondary phases.

Fracture behavior of Zr55Cu30Al10Ni5 bulk metallic glass was investigated under quasi-static compression at strain rate of 10−4/s using an Instron testing machine and dynamic split Hopkinson bar (SHPB) compression with strain rate of about 1900–4300/s. Pronounced strain softening, especially past the peak stress, was observed under SHPB tests and compared with the distinct flow serrations under quasi-static tests. Scanning electron microscope revealed that the angle between the loading axis and major shear plane is less than 45°, deviating from the maximum shear stress plane. Microscopically, unlike the ordinary veinlike pattern found in quasi-static compression, the elongated veinlike pattern was observed at the onset position of rapid shearing under dynamic test. A closely arrayed dendritelike structure dominated the dynamic fracture, consequently, and should be the major pattern representing the rapid shear band propagation. In addition, a transition state from veinlike to dendritelike pattern was observed at the final instantaneous fracture region in quasi-static tests. Evidence revealed the characteristic dimension of dynamic fracture surface complies with Taylor’s meniscus instability criterion. The roles of free volume and adiabatic heating on the fracture strength and stress concentration on the fracture morphology are also discussed.

The mechanical properties and corresponding microstructure development of the AZ31 Mg alloy after treatment with equal channel angular pressing (ECAP) and subsequent electropulsing (ECP) was investigated. Comparing the ECAP+ECP-treated AZ31 alloy with the ECAP-treated alloy, the elongation to failure was improved significantly, while the yield stress and the ultimate tensile strength were not decreased, the grain sizes were slightly increased and more homogeneous, and the texture was barely changed. The main mechanism for the evolution of the structures and properties might be ascribed to the increased nucleation rate on recrystallization and the decreased dislocation density during the ECP treatment. It was reasonable to expect that the ECAP+ECP treatment would provide a promising approach for enhancing the mechanical properties of the Mg alloys.

Dispersed uniform spherical silver particles were prepared in the absence of a protective colloid by rapidly mixing concentrated isoascorbic acid and silver-polyamine complex solutions. By varying the nature of the amine, temperature, concentration of reactants, silver/amine molar ratio, and the nature of the silver salt, it was possible to tailor the size of the resulting metallic particles in a wide range (80 nm to 1.3 μm). The silver spheres were formed by aggregation of nanosize subunits, the presence of which was detected by both electron microscopy and x-ray diffraction. Due to its simplicity, high metal concentration, and the absence of polymeric dispersants, the described method represents an advantageous route to manufacture cost-effectively dispersed uniform silver particles for electronic applications.

MgTe2O5 ceramics were prepared by solid-state route. These materials were sintered in the temperature range of 640–720 °C. The structure and microstructure of the compound was investigated using x-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM) techniques. The dielectric properties of the ceramics were studied in the frequency range 4–6 GHz. The MgTe2O5 ceramics have a dielectric constant (ϵr) of 10.5, quality factors (Qu × f) of 61000 at 5.3 GHz, and temperature coefficient of resonant frequency (τf) of −45 ppm/°C at the optimized sintering temperature of 700 °C. The microwave dielectric properties of these materials at cryogenic temperatures were also investigated.

We conducted an investigation into the thermodynamic properties of two stoichiometric CaCu3Ti4O12(CCTO) samples prepared by solid-state reaction and soft chemistry methods to probe the stability of the material relative to simpler oxide constituents (e.g., CaO, CuO, and TiO2) over a wide temperature range. Thermodynamic functions (i.e., heat capacity, formation enthalpies, entropies, and Gibbs free energies) have been measured from near absolute zero to 1100 K using calorimetric methods, including drop solution, low-temperature adiabatic relaxation, and differential scanning calorimetry. In addition, the thermodynamic characteristics of the magnetic-phase transition from the antiferromagnetic to the paramagnetic state are reported. It has been shown that CCTO is very stable relative to constituent oxides and calcium titanate at room temperature and higher, independent of the synthesis route. The enthalpic factor is dominant in the thermodynamics of CCTO, with the entropic factor having almost no effect on the stability of the compound relative to other oxide assemblages. The recommended values for the standard molar enthalpy of formation from constituent oxides and from elements at 298.15 K are −122.1 ± 4.5 and −4155.7 ± 5.2 kJ/mol−1, respectively. The mean of the third law entropy at 298.15 K is 368.4 ± 0.1 J/mol−1/K−1. Based on the thermodynamic data reported, the study confirms the possibility of CCTO decomposition in a reducing atmosphere or CO2 under conditions recently observed in experiments.

The recent development of experimental techniques that rapidly reconstruct the three-dimensional microstructures of solids has given rise to new possibilities for developing a deeper understanding of the evolution of microstructures and the effects of microstructures on materials properties. Combined with three-dimensional (3D) simulations and analyses that are capable of handling the complexity of these microstructures, 3D reconstruction, or tomography, has become a powerful tool that provides clear insights into materials processing and properties. This introductory article provides an overview of this emerging field of materials science, as well as brief descriptions of selected methods and their applicability.

New porous biomaterials based on hydroxyapatite (HAp) were designed as obturation materials for dental cavities. Synthetic HAp powder with a particle diameter of 150 μm was agglutinated using three different polyurethane monocomponents (rigid, semi-rigid, and flexible), enabling the matching of their properties to those of real teeth. Alumina particles were also added in some cases. Our new hybrid materials contain up to 60% HAp. Interconnected pores range in size from 100 to 350 μm, while the pore volume fraction varies between 25% and 60%. Most of these materials possess the right morphology for implants and prostheses because their porous structures can be vascularized for bone and tooth ingrowth. Some samples also contain alumina particles to improve the abrasion resistance and to support the stresses produced during mastication. The materials were characterized by x-ray diffraction, scanning electron microscopy, and mechanical testing, along with abrasion, scratch, sliding wear, friction, and staining tests.

Poly(amic acid) (PAA)–clay nacrelike composite films have been prepared by electrophoretic deposition of an emulsion of PAA, which was synthesized from pyromellitic dianhydride and 4,4′-dianminodiphenyl ether (ODA), containing various loadings of ODA-modified montmorillonite (MMT). The layered silicate was intercalated through reacting with PAA, and the ordered layered assembly of the PAA–MMT composite films was successfully accomplished, as conformed by Fourier transform infrared analysis and x-ray diffraction. The structural characterization of the films was supported by scanning electron microscopy, which displayed an ordered layered structure. The thermogravimetric analysis showed the content of the ODA-modified clay in PAA–MMT composite films that changed from 14.3 to 32.1 wt% and the improved thermal properties of the composite films. The mechanical properties of the composites were measured by tensile test. It was found that the modulus and strength of the composite films were greatly improved compared to those of the pure polymer film. An increment of about 155% in the modulus and 40% in the tensile strength were obtained from the composite films.

Synchrotron x-ray microtomography is a characterization technique increasingly used to obtain 3D images of the interior of optically opaque materials with a spatial resolution in the micrometer range. As a nondestructive technique, it enables the monitoring of microstructural evolution during in situ experiments. In this article, examples from three different fields of metals research illustrate the contribution of x-ray tomography data to modeling: deformation of cellular materials, metal solidification, and fatigue crack growth in Al alloys. Conventionally, tomography probes the 3D distribution of the x-ray attenuation coefficient within a sample. However, this technique is also being extended to determine the local crystallographic orientation in the bulk of materials (diffraction contrast tomography), a key issue for the modeling of microstructure in metals.

Stoichiometric silicon carbide coatings the same as those used in the formation of TRISO (TRistructural ISOtropic) fuel particles were produced by the decomposition of methyltrichlorosilane in hydrogen. Fluidized bed chemical vapor deposition at around 1500 °C, produced SiC with a Young’s modulus of 362 to 399 GPa. In this paper we demonstrate the deposition of stoichiometric silicon carbide coatings with refined microstructure (grain size between 0.4 and 0.8 μm) and enhanced mechanical properties (Young’s modulus of 448 GPa and hardness of 42 GPa) at 1300 °C by the addition of propene. The addition of ethyne, however, had little effect on the deposition of silicon carbide. The effect of deposition temperature and precursor concentration were correlated to changes in the type of molecules participating in the deposition mechanism.

Scale-dependent microstructure and electronic transportation of Ni/Al-type nanomultilayers as a function of the bilayers number, the modulated ratio, and the periodicity were investigated. The deposited multilayers have anisotropic nanocrystalline structure and asymmetrical interfaces. This special interfacial feature is the result of asymmetrical diffusion of Ni to Al lattice near the Ni–Al interface. Anomalous resistivity enhancement increases with decreasing both the periodicity and the modulated ratio, but is insensitive to the number of bilayers. Accounting for the effects of grain boundary and interface boundary, the dominative mechanism at distinct length scales can be interpreted with the modified model of those of Fuchs–Sondheimer and Mayadas–Shatzkes. Especially for the thinnest film with smallest modulated ratio, the intermixing effect turns out to be the crucial mechanism in the electronic transportation of metallic nanomultilayers.

Highly aligned nanowire bundles were controllably fabricated through the reaction of Si with oxygen, using molten Ga and Au as catalysts. Scanning electron microscopy reveals that the bundles have the ability to self-assemble into various morphologies, a few of which, including one that strikingly resembles a sunflower, were not reported before. Examinations of the bundles by transmission electron microscopy show that they contain fine, amorphous SiOx nanowires, with x ranging from 1.2 to 1.5. In the sunflower-like morphology, highly packed bundles form the disc florets and loosely packed bundles around the rim of the disc form the ray florets. We have studied the conditions under which the sunflower-like morphology could be obtained and suggest a possible mechanism for its growth. Room-temperature cathodoluminescence spectra of the nanowire bundles show that they emit an intense broad-band light covering the entire visible range.