An ultra-violet (UV) curable ink jet 3D printed material was characterized by an inverse finite element modeling (IFEM) technique employing a nonlinear viscoelastic–viscoplastic (NVEVP) material constitutive model; this methodology was compared directly with nanoindentation tests. The printed UV cured ink jet material properties were found to be z-depth dependent owing to the sequential layer-by-layer deposition approach. With further post-UV curing, the z-depth dependence was weakened but properties at all depths were influenced by the duration of UV exposure, indicating that none of the materials within the samples had reached full cure during the 3D printing process. Effects due to the proximity of an indentation to the 3D printed material material-sample fixing interface, and the different mounting material, in a test sample were examined by direct 3D finite element simulation and shown to be insignificant for experiments performed at a distance greater than 20 µm from the interface.

Mechanical integrity of the interfacial region between ceramic coatings and substrates is critical to high performance coated mechanical components and manufacturing tools. Mechanical failure of the coating/substrate interfacial region often leads to catastrophic failure of the coated system as a whole. Despite extensive research over the past two decades, quantitative assessment of the mechanical response of coating/substrate interfacial regions remains a challenge. The lack of reliable protocols for measuring the mechanical response of coating/substrate interfacial regions quantitatively hampers the understanding of key factors controlling the mechanical integrity of coating/substrate interfaces. In this paper, we describe a new micro-pillar testing protocol for quantitative measurement of critical stresses for inducing shear failure of interfacial regions in ceramic-coating/metal-adhesion-layer/substrate systems. We observe significant differences in the critical stress for shear failure of interfacial regions in CrN/Cu/Si, CrN/Cr/Si, and CrN/Ti/Si systems. The present testing protocol has general applicability to a wide range of coating/interlayer/substrate systems.

The present study was focused to investigate mechanical properties of ZnO thin films deposited on fused quartz substrates at different sputtering deposition pressures (5, 10, 15, and 20 mTorr) using DC sputtering. The crystallinity and microstructure show a marked influence on the mechanical properties of ZnO thin films. The structural evolution of the thin films is in (002) plane and influenced by deposition pressure. The intensity of (002) peak of the films rises initially and decreases with further increasing deposition pressure. The mechanical properties such as hardness, Young’s modulus, and coefficient of friction of ZnO thin films were measured using three-sided pyramidal Berkovich nanoindentation. The adhesion strength of thin films was measured by using scratch test under ramp loading. Load–displacement profile of thin films at continuous indentation cycle without any discontinuity revealed no fracture, cracking event, and defects, which is a consequence of dense microstructure and good adherence of films to the substrate.

In this work, nano, micro, and macro-indentation tests under standard or multicycle loading conditions were performed for studying the mechanical behavior of a crown borosilicate glass sample with the objective to study the scale effect in indentation and the influence of cracks formation on the assessment of mechanical properties. When no cracks were initiated during the indenter penetration, especially for low indentation loads, the mechanical properties were deduced by applying different methodologies, (i) Standard (or monocyclic) loading, (ii) Continuous Stiffness Measurement mode, (iii) Constant and progressive multicycle loading, and (iv) Dynamic hardness computation. It has been found independently of the loading conditions, Martens hardness and elastic modulus are approximately 3.3 and 70 GPa, respectively. However, when cracking and chipping are produced during the indentation test, two damage parameters related to hardness and elastic modulus can be used for representing the decrease of the mechanical properties as a function of the relative penetration depth.

Nanoindentation techniques are commonly used to characterize nanomechanical properties of microscaled and nanoscaled materials. Nanoindentation using a cylindrical flat-tip indenter has a constant contact area which makes it a reliable source to find material’s yield strength as well as other mechanical properties. However, an angular misalignment of the indenter with the specimen results in experimental error. In this work, the effects of angular misalignment on the nanoindentation testing with a cylindrical flat-tip indenter were numerically analyzed. A three-dimensional nanoindentation solid model was generated, computer modeling based on finite element analysis was conducted. The angle of misalignment ranged from 0° to 1°. Young’s modulus and hardness were evaluated. Based on the hemispherical stress–strain distribution assumption of an elastic plastic indentation, corrected depths and modifiers were proposed for adjusting material’s 0.1% offset and 0.2% offset yield strengths. Low carbon steel AISI 1018 was selected as sample material for indentation testing and modeling validation.

The strain-rate sensitivity of the flow stress represents a crucial parameter for characterizing the deformation kinetics of a material. In this work a new method was developed and validated for determining the local strain-rate sensitivity of the flow stress at different plastic strains. The approach is based on spherical nanoindentation strain-rate jump tests during one deformation experiment. In the case of ultrafine-grained Al and ultrafine-grained Cu good agreement between this technique and macroscopic compression tests has been achieved. In contrast to this, individual spherical nanoindentation experiments at constant strain-rates resulted in unrealistically high strain-rate sensitivities for both materials because of drift influences. Microstructural investigations of the residual spherical imprints on ultrafine-grained Al and ultrafine-grained Cu revealed significant differences regarding the deformation structure. For ultrafine-grained Cu considerably less activity of grain boundary sliding has been observed compared to ultrafine-grained Al.

The propagation of a pre-existing center crack in single crystal tungsten under cyclic loading was examined by molecular dynamics (MD) simulations at various temperatures. The results indicated that the deformation mechanism and fracture behavior at crack tip were differences for variously oriented cracks. The [001](010) crack propagated as the form of the formation of slip, while the deformation mechanisms of [10−1](101) crack were blunting voids at 300 K. At higher temperature, many more slip systems were activated resulting in the change of mode of crack propagation. Simulated results showed that the effect of temperature on deformation mechanism and fracture behavior of [001](010) crack was more sensitive than that of [10−1](101) crack. Meanwhile, the influence of a 5〈310〉{110} model grain boundary (GB) on crack propagation was also discussed. Detailed analysis showed that the grain boundary resisted the crack growth by changing the deformation mechanisms and the path of crack propagation at crack tip before the crack reached the grain boundary, and had an important influence on the crack growth rate.

Microstructural and crystallographic aspects of high-velocity forming or “rapid” forming of rolled sheets of pure copper have been investigated in this work. Significant changes in crystallographic orientation and microstructure were observed when thin (0.5 mm) metal sheets of annealed copper were subjected to high strain rate deformation in a conventional shock tube at a very low impulse magnitude (∼0.2 N s), which is inconceivable in conventional metal forming. Shock-loaded samples show characteristic texture evolution with a high brass {110}〈112〉 component. A significant change in grain orientation spread was observed with increasing amount of effective strain without any drastic change in grain size. The texture after deformation was found to be strain-dependent. The path of texture evolution is dependent on the initial texture. Misorientation was limited to less than 5°. Deformation bands and deformation twins were observed. There was a decrease in twin [Σ3 coincidence site lattice (CSL)] boundary number fraction with increasing strain due to the change in twin boundary character to high-angle random boundary (HARB) as a result of dislocation pile up. The study shows the probability of a high-velocity shock wave forming pure Cu.

The effect of peak shock stress on the incipient spallation damage in a cylindrical sample under sweeping detonation is presented. The free surface velocity curve was measured by photon Doppler velocimetry and the quantitative investigation of voids in a spalled sample was performed using X-ray computer tomography. The results revealed that the maximum volume and the mean volume of voids in the spalled sample increased with increasing shock stress. The sphericity of voids decreases with the increasing of shock stress. The rod voids were the result of the independent growth of voids along the grain boundaries in samples with lower shock stress, while the rod shaped voids in sample with higher shock stress were formed due to coalesce. The rod voids can be found in a cylindrical sample, while the voids in plate samples were in the shape of spheres or ellipsoids, and the difference of stress state induced by the curvature in the geometry of samples may be the main reason.

Selective laser melting (SLM) technology efficiently solves the current manufacturing challenges of high-performance porous structure components, due to its freeform fabrication principle. As the most basic and crucial structure element, the nodes of porous structure component play an important role in its mechanical property. In this study, finite element method was used to investigate the thermal behavior during SLM processing of micro-scale node-structure. The dynamic size of molten pool was continuously predicted and consequently the typical “necking” effect was found, which was consistent with the experiment results. Besides, the influence of laser scan speed on temperature and temperature gradient of molten pool was also analyzed. The results indicated that the “necking” effect became more conspicuous with the applied scan speed increasing, which significantly deteriorated the mechanical property of porous structure components.

Isothermal compression testing of Ti–5.8Al–3Sn–5Zr–0.5Mo–1.0Nb–1.0Ta–0.4Si–0.2Er titanium alloy is performed on a Gleeble-3500 thermal simulator, and the corresponding microstructures are analyzed to clarify the softening mechanism and participates evolution. A constitutive equation compensated by strain has been established to describe the hot deformation behavior of the alloy. The deformation activation energies are calculated to be 369760.93–699310.86 J/mol in α + β two-phase region and 268030.03–325800.41 J/mol in β single-phase region. At a temperature of 880 °C, the main softening mechanism is the continuous dynamic recrystallization of lamellar α colony, controlled by the mechanical rotation of the sub-grain followed by dislocation climbing and annihilation by diffusion. Meanwhile, the dominant softening mechanism is the discontinuous dynamic recrystallization of β phase during the deformation at temperatures of 920 °C–1080 °C. Silicide containing Er with an average diameter of 20 nm is formed during the water quenching.

We present a novel route to fabricate 3D nanoporous α-Ti foams by dealloying of TiCu master alloy in solid state using Mg powders. Pure open-cell nanoporous α-Ti foams are fabricated with BET surface area of 34.4 ± 0.8 m2/g and pore size in the range of 2–50 nm. The dealloying using powders is a solid state chemical reaction process to form Cu2Mg phase and Ti/Mg nanocomposites. The constituent of Cu in the TiCu alloy was dissolved into Mg powders thanks to the kinetics of interface reaction and volume diffusion. The pore-forming mechanism is a solid-state interdiffusion process. The ligament coarsening is from 492 to 650 nm with increasing of the dealloying temperature. The hardness and elastic modulus in nanoporous α-Ti foam follow linear decay fit with ligament size increasing. Our results demonstrate a facile strategy for the fabrication of nanoporous Ti foams with novel nanostructures and tailored properties.

YCrO3 (YCO) perovskite has been originally reported to be a biferroic with antiferromagnetic and ferroelectric (FE) properties, in which the origin of FE in YCO remains ambiguous. However, further studies reveal the presence of a global orthorhombic Pnma structure with a local structural heterogeneity. In this study, we discuss the high temperature phonon modes and their inter-relation to local structural distortions in YCO perovskite through Raman spectroscopy experiments and density functional theory (DFT) calculations. We observe that the Raman active B3g(3) out of phase scissor mode (SM) disappears above the dielectric transition temperature (T c) commensurate with the local structural distortions. DFT calculations show that the transformation of a room temperature Y-cation distorted orthorhombic structure to a perfect orthorhombic structure above the dielectric transition temperature in which the Y cation is undisplaced could lead to the conversion of SM with symmetry B3g to Raman inactive B1u mode.

Tungstate based phosphors have efficient absorption in the UV region and can be used for UV-pumped light emitting. For novel and effective materials and synthesis methods in this system, a series of Eu3+ and Tb3+ co-doped NaY(WO4)2 phosphors have been synthesized via the molten salt method. The powder X-ray diffraction (PXRD) patterns, scanning electronic microscope (SEM), and photoluminescent spectra have been characterized for the prepared samples. The results show the flux (NaCl) not only decreases the reaction temperature (700–900 °C) than the normal solid state synthesis (∼1000 °C), but also controls the morphology of the products. The shape and size of products can be changed simply and effectively by the reaction conditions, such as temperature and heating time. It is also found that the emission colors of the samples can be tuned from red to green by simply adjusting the doping concentrations of Eu3+ and Tb3+ ions under the same wave length excitation, which has potential applications for multi-color display and illumination as a single-component phosphor.

Classical molecular dynamics (MD), along with a bond-order potential for GaAs, has been used to study threshold displacement energies (E d) of Ga and As recoils. Considering the crystallographic symmetry of GaAs, recoil events are confined in four unit stereographic triangles. To investigate the displacement energy’s dependence on crystallographic orientation, more than 3600 recoil events were simulated to uniformly sample values of E d. Various defect configurations produced at these low energy recoils and the separation distances of Frenkel pairs were quantified and outlined. For both Ga and As, the minimum, $E_{\rm{d}}^{{\rm{min}}}$ , is found to be 8 eV, but the maxima, $E_{\rm{d}}^{{\rm{max}}}$ , are 22 and 28 eV for Ga and As, respectively. The distribution of E d within unit stereographic triangles indicates that E d shows a weak dependence on the recoil directions, in contrast to other semiconductors. The average threshold displacement energy is 13 ± 1 eV, which is in excellent agreement with available experiments.

One conceptually different approach has been developed to synthesize Ti3+ self-doped TiO2−x mesocrystals to narrow the band gap of TiO2. This simple and economical one-pot solvothermal method uses TiCl3 and tetrabutyltitanate (TBT) as a precursor and exhibits practical application. Different morphology including uniform spindle shape, tetragonal bipyramid, and capsule-like mesocrystals can be tailored easily by tuning the precursor ratio of TiCl3 to TBT. We have shown that our band gap engineered TiO2−x exhibits unique mesocrystal phase and owns substantial high visible light driven photocatalytic activities. Electron paramagnetic resonance (EPR) studies of this sample verified the presence of oxygen centered radicals, namely, hydroxyl (·OH) and superoxide radicals (O2 −·/·OOH). The catalysts have been characterized using transmission electron microscope, fluorescence spectra, Raman spectra, EPR, X-ray photoelectron spectroscopy, X-ray diffraction (XRD), Ultraviolet–visible absorption spectra, etc. It shows high catalytic stability. The findings of this work provide new insights for developing morphology tailored for visible light driven devices and other applications via controlled band gap engineering.

In this study, the density functional theory (DFT) and Monte Carlo (MC) simulations were conducted to determine the equilibrium conformation of Pt2Ru3 nanoparticles with diameters 1.0–3.5 nm at finite temperature. DFT calculations were carried out to estimate the binding energy using slab configurations and energy could be correlated with some structural descriptors and multilinear regression equations to calculate the binding energy from descriptors related to the number of a specific bond to neighboring atoms. MC simulations were carried out to obtain the equilibrium conformation of atoms in Pt2Ru3 at 150–363 K. MC simulations’ result shows that atoms of the same element tend to segregate each other, and Pt/Ru ratio on the surface increases with increasing particle size; also, most of the Pt are located on the surface whereas most of the Ru are located on the subsurface or at the core sites. It is qualitatively exhibited that the Pt/Ru ratio on the surface decreases with increasing temperature.

In this work, o-phenylenediamine-m-phenylenediamine copolymer dots (omCPs) with designed surface groups are synthesized and characterized. Here, we explored a simple, rapid semiquantitative detection system for Cu2+ with a wide detection range (5–7 orders of magnitude) based on the fluorescence in the solid state of omCPs and their tunable detection limits. The construction and application of the rapid semiquantitative detection system for Cu2+ are developed and demonstrated for the practical applications. What’s more, the detection limit can be modulated easily by adjusting the surface groups of these dots through the monomer dose control before the co-polymerization. Moreover, we demonstrated that this new technological approach is suitable for the semiquantitative determination of other ions pollutants (i.e., Na+, K+, Cu2+, Pb2+, Hg2+, and NO2 −) in environmental water.

A pure and (Fe–Ni) doped tin oxide thin films were formed on glass substrates by sol–gel dip coating method. Some characterization techniques are used as X-ray diffraction (XRD), UV–vis spectroscopy and atomic force microscopy (AFM) to study the effect of method conditions and dopants on the structural, morphological, and optical properties of thin films. According to XRD results, no phase attributed to Fe or Ni were detected, which suggests the incorporation of Fe and Ni in SnO2 network. All the diffraction peaks can be assigned as rutile phase of pure SnO2 except (111) is attributed to cubic phase. The optic analyses have shown an average transmittance between 70 and 90%, and showed a direct band gap reducing with increase in Fe doping (3.82–3.72 eV) and Ni content (3.82–3.69 eV). AFM images have revealed that surface roughness is affected strongly by deposition conditions and dopant contents.

The BiOBr/Ag3PO4 composites were fabricated by a facile in situ deposition of Ag3PO4 nanoparticles on the BiOBr microsheets and analyzed by X-ray diffraction, scanning electron microscope, high resolution transmission electron microscope, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance absorption spectra, Fourier transform infrared, Raman, photoluminescence (PL), and photoelectrochemical techniques. The photocatalytic performances of as-prepared samples were investigated and compared through degradation of Rhodamine B (RhB) solution. The results suggested that 30 wt% amount of BiOBr in the composites possessed the highest photocatalytic activity. The remarkably improved photocatalytic performances of BiOBr/Ag3PO4 composites could be ascribed to the efficient separation of electron–hole pairs, due to suitable energy band potentials between BiOBr and Ag3PO4. Furthermore, the photoelectrochemical and PL tests verified the separation and transfer efficiency of charges was promoted.