The purpose of this paper is to propose a critical assessment of Young’s modulus determination of coated materials using Impulse Excitation Technique (IET). In this technique, the coated substrate is excited by an impulse and the acoustic vibrations are recorded. The frequency of the first bending mode is then used in a mechanical model to obtain the Young’s modulus of the coating. The existing models are based on two different theories: the flexural rigidity of a composite beam and the Classical Laminated Beam Theory (CLBT). The aim of the present paper is to assess the accuracy (trueness and precision) of the technique. For this, different models proposed in the literature are compared with a finite element model of the specimen for various conditions. The trueness and precision of models were evaluated and the best model was identified. Then a detailed uncertainty budget is performed to identify and quantify the most influent factors on the global uncertainty.

First-principles calculations are performed to investigate the structural, elastic, and thermodynamic properties of Ni3SnP, Ni2SnP, Ni10SnP3, and Ni2P (here, Ni2P is used for comparison with Ni2SnP). Through calculation, the three ternary Ni–Sn–P intermetallics are all thermodynamic stable but Ni3SnP is elastically unstable. Ni2SnP has the largest degree of elastic anisotropy and is more brittle than Ni2P while Ni10SnP3 is close to be isotropic. The Debye temperature together with the Cahill’s model and Clark’s model are used to investigate the thermal conductivity of the compounds. The Debye temperature follows the sequence of Ni10SnP3 > Ni2SnP > Ni2P. Based on the Clark’s model, the minimum thermal conductivity is ranked as Ni10SnP3 > Ni2P > Ni2SnP which means the heat transfer property of Ni2SnP is lower than Ni2P when the temperature is higher than Debye temperature. The electronic density of states is analyzed. The origin of the elastic anisotropy of Ni2SnP is investigated.

Understanding film initiation and growth mechanisms at the atomic level is crucial to obtain high-quality nonpolar ZnO films. Using the advanced reactive force field-based molecular dynamics method, we theoretically studied the effect of substrate temperature (350–950 K) on the quality, layer develop mechanism and defect formation of ZnO films. Investigation of the energy, radial distribution function, layer coverage, sputtering and injecting phenomena indicated that the present films grown at 500–600 K possessed the optimal quality. Further investigation of the growth condition, instant film profiles, interfacial microstructure evolutions and layered snapshots revealed that, addition of atoms on newly formed localized films can induce some partially bonded or extruded atoms out of the film plane. Further adherence of depositing atoms to these unstable or extruded atoms induces the initiation and growth of a new layer.

In the present work, we report the development of phase pure and highly crystalline stibnite Sb2S3 nanostructures by a surfactant-mediated hydrothermal method. Polyvinylpyrrolidone (PVP) as the surfactant has a striking effect on the assembly of nanorods into dumbbell shaped nanorod-bundles. While nanorods with high aspect ratio were formed in absence of the surfactant, dumbbell shaped nanorod bundles were obtained using the surfactant. The structural, morphological, and optical properties were examined by X-ray diffraction (XRD), Raman scattering, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy (XPS), and UV–visible spectrophotometer. Both XRD and Raman spectroscopy confirmed the formation of orthorhombic phase pure stibnite (Sb2S3). The ratio of Sb to S is found to be close to 2:3, corresponding to Sb2S3. The optical band gap varied in the range of 1.65–1.68 eV depending on the concentration of the surfactant.

A series of Eu3+ and Dy3+ singly and doubly doped Gd2MoO6 phosphors were synthesized with solid state reactions. The X-ray powder diffraction analysis of phosphors shows that substitution of Eu3+ and Dy3+ does not change the host structure of phosphors. The absorption spectra measurements show that un-doped Gd2MoO6 can absorb near ultraviolet light without any visible light emission. However, energy absorbed by Gd2MoO6 can be effectively transferred to doped Eu3+ and Dy3+ and makes them emit blue, yellow, and red light, respectively. White light can be obtained by combining blue, yellow, and red emission. The doping of Dy3+ plays a major role for the formation of white light. The introduction of Eu3+ can remarkably decrease the color temperature of the white light emission. The measurement of the temperature-dependent luminescent properties indicates that the phosphors present a good thermal stability. Our investigation indicates that Gd2MoO6:Eu3+,Dy3+ is a potential candidate for white light emitting diodes applications. It also provides a new sight for the achievement of white light emission.

In this research, Ce3+ and Tb3+ doped alkaline-earth silicate Sr2MgSi2O7 phosphors have been synthesized by solid-state reaction. The results show that the Sr2−x MgSi2O7:xCe3+ phosphors exhibit a violet–blue emission with excitation at 348 nm, whereas the Sr2−y MgSi2O7:yTb3+ phosphor show a green emission with excitation at 243 nm. In addition, the structure of Sr2MgSi2O7 host has been analyzed by Crystalmaker program. Staggered arrangements of [SiO4] and [MgO4] units in the Sr2MgSi2O7 system underlie possible chemical tuning and phase segregation, providing a potential candidate of tunable luminescence. A red shift of wave length is clarified by crystal field theory and Van Uitert expression. The FESEM image of Sr1.99MgSi2O7:0.01Ce3+ phosphors reveal that it has a proper particle size for application in WLEDs. With different Tb3+ doping concentration, the CIE chromaticity coordinates Sr2MgSi2O7:Tb3+ phosphors still remain a steady position. These results indicate that Sr2−x MgSi2O7:xCe3+, Sr2−y MgSi2O7:yTb3+ phosphors are promising phosphors for WLEDs.

The in situ synthesis of nickel-based composite coating reinforced with WC particle on mild steel has been investigated. Results show a planar crystal at the interface and some relatively coarse columnar dendrites on the side of the coating near the substrate. The synthesized WC particles homogenously distribute in the coating without cracks and pores. The maximum size, mean size, and volume fraction of the WC particle is 270 µm, 35 µm, and 71%, respectively. The microhardness value of the prepared coating can be up to a maximum of 755 HV2. The synthesized WC particles generally show a unique triangular prism shape, whose evolution rule and growth mechanism are investigated by Bravais–Friedel–Donnay–Harker theory. It is deduced that crystal structure and interface energy play important role in determining the shape of WC, which evolves from sphere to hexagonal prism and finally to triangular prism.

Effect of Ce addition on electric conductivity of Al alloys is investigated in this paper. Addition of proper amount of Ce leads to a remarkable improvement of electric conductivity. Adding Ce enhances the formation of binary, ternary, or quaternary compounds of Ce, Si, Fe, and Al and reduces the solution content of Fe and Si in the Al solution accordingly, well consistent with the Al lattice constant calculations and the Bragg models. Density of state adjacent to Fermi level of Al–Ce solution is obviously different from other solute atoms involving in La, Fe, and Si etc. and fairly similar with that of pure Al. Two possible contributions of Ce lead to the remarkable improvement of conductivity. First, Ce addition alleviates the lattice static distortion of Al solution and hence expands the average electrical free path. Second, Ce-induced alteration of electron energy band structure may intensify the effective electron number that participates conduction.

Ball milling induced the formation of nanocrystalline and amorphization phase in Fe–25.68% Dy2O3 powder mixtures (mass fraction, %). The microstructure was investigated by using X-ray diffraction and transmission electron microscopy. The transformation of Dy2O3 from cubic to monoclinic crystal structure and then to the amorphization was observed during ball milling. A few Dy atoms were dissolved into Fe crystal structure, which was discussed using mechanical kinetics. After 48 h of ball milling, the homogenous mixtures of supersaturated nanocrystalline solid solution of Fe (Dy, O) and Dy2O3 amorphization were formed and the elements of Fe, Dy, and O were distributed uniformly in the ball-milled particles. During the whole ball mining process, a rapid decrease in Fe grain size was observed over the initial time period, while a constant value was presented in later stage, resulting in a final size of about 20 nm. The mechanism of the microstructural evolution of powder mixtures was analyzed and discussed.

This research article addresses the effect of fillers on the high-temperature corrosion behavior of AISI 347 weld joints. Multi-pass pulsed current gas tungsten arc welding was carried out on 6.67 mm thick plates of AISI 347 using three different fillers namely ER347, ER2553, and ERNiCrMo-3. The fusion zone microstructures of AISI 347 employing ER2553 and ERNiCrMo-3 exhibited columnar and dendritic grain growth; whereas vermicular delta ferrite was observed at the fusion zone of ER347 welds. Tensile studies showed that the weld employing ERNiCrMo-3 exhibited better tensile strength than the parent metal. High-temperature corrosion studies were carried out on the fusion zones by exposing the coupons to an aggressive, synthetic molten-salt incinerator environment containing 40% Na2SO4–40% K2SO4–10% NaCl–10% KCl at 650 °C for 50 cycles. The studies attested that the fusion zone employing ERNiCrMo-3 exhibited better corrosion resistance than the other two fillers used in the study. Spallation of oxides was witnessed due to the dissolution of Cr2O3 in the ER347 and ER2553 fusion zones. The hot corroded samples were characterized using surface analytical techniques.

Boron carbide (B4C) ceramic particles were used as reinforcement material to produce aluminum (Al) matrix composites by squeeze casting method. Four different B4C contents as 0, 3, 5, and 10 wt%, and three different squeeze pressures as 0, 75, and 150 MPa were used in which the samples consisted of pure Al without B4C and the samples obtained without applying pressure were used as control samples. To determine the effect of squeezing pressure and the amount of B4C added on machinability and mechanical properties, average chip length and surface roughness of the samples were evaluated and hardness measurements were accomplished, yield and ultimate tensile strengths were determined, respectively. Also, the changes in density and microstructure were investigated. B4C reinforcement was found to decrease the average chip length and density of the samples while increasing the hardness and surface roughness. On the other hand, application of squeeze pressure had a positive effect on the densification and mechanical properties of the samples.

This study investigates the synthesis, characterization, and corrosion behavior of AA6063 composites with the inclusion of micron-sized titanium carbide (TiC) particles with different weight percentages. AA6063/TiC particulate composites containing 0, 3, 6, 9, and 12 weight percent of TiC particles were produced by stir casting. The homogeneous dispersion of TiC particles in the AA6063/TiC composites was revealed from the scanning electron microscopy analysis. Energy dispersive X-ray spectroscopy analysis was conducted to ensure the presence of reinforcement particles in the matrix. Mechanical and corrosion properties of the produced composites are evaluated. The addition of TiC particles to the AA6063, the mechanical, electrical, and corrosion properties are initially increased and then decreased. Mechanical and corrosion study shows that the presence of 9 wt% of TiC particles in the matrix improved mechanical properties than other combination of TiC with the matrix material.

This study investigated the effects of 1 wt% SiC nanoparticles addition on the microstructures and mechanical properties of Mg9Al–1Si (wt%) alloy subjected to equal channel angular pressing (ECAP). Results showed that addition of SiC nanoparticles could refine matrix grain, Mg17Al12 and Mg2Si phase of as-cast alloy, but the Mg17Al12 phase still exhibited network structure and the morphology of Mg2Si phase was still Chinese-script type. During the ECAP process, network Mg17Al12 and Chinese-script shaped Mg2Si phases were partially broken down into fine particles (∼10 µm) and much finer particles (∼2 µm) respectively. In particular, these Mg17Al12 and Mg2Si particles were uniform distribution in ECAPed Mg9Al–1Si–1SiC composite. The well-distributed particles and the existence of SiC nanoparticles could promote the formation of fine DRXed grains through enhanced grain boundary pinning. During tensile testing at room temperature, ECAPed Mg9Al–1Si–1SiC composite exhibit optimal mechanical properties, the ultimate tensile strength and elongation to failure were reached to 255 MPa and 7.9%, respectively. Furthermore, at elevated temperature of 150 °C, the tensile strength and elongation to failure were considerably increased compared to an ECAPed, SiC-free Mg9Al–1Si alloy.

As the operating temperature of disk service was elevated from 650 °C to 700 °C, the creep properties urged to be paid attention. To investigate the creep properties of spray-formed low solvus, high refractory (LSHR) superalloy at about 700 °C, creep tests were conducted under seven different stress ranging from 690 MPa to 897 MPa. By means of creep curves and fracture microstructure observation, the creep behaviors and fracture mechanisms of spray-formed LSHR were analyzed. Stress exponent of the alloy was comparable to other disk superalloys such as Waspaloy and Inconel 718. It was interesting to find a transition in the creep behavior in two stress regimes. The contribution of grain boundary sliding in the low stress regime was greater than that in the higher stress. Under higher stress microcracks initiated along the intragranular slip bands because of strain concentration. The spray-forming LSHR exhibited a good creep resistance at low stress compared with other two superalloys by using Larson–Miller parameter, which was consistent with the transition of fracture behaviors.

The high-cycle fatigue (HCF) behavior is significantly affected by surface roughness, especially for high strength metal FV520B-I. However, with surface roughness effect, neither the fatigue property, nor the high-cycle fatigue life model about FV520B-I with surface roughness has been reported. In this paper, designed fatigue experiment using the specimen with different surface roughness is presented to study the effectiveness of the roughness to the fatigue. The observations of the fatigue crack initiation sites and the crack propagation. Then the high cycle fatigue behavior of FV520B-I affected by surface roughness is analyzed. The existing very-high-cycle fatigue life model is not well-fit for high-cycle fatigue model of FV520B-I. A NEW high-cycle fatigue life prediction model of FV520B-I, taking surface roughness as a main effective variable is proposed. The model is built up by a comprehensive use of experimental data and the traditional fatigue modeling theory. The new finding between the fatigue strength coefficient and stress amplitude, with surface roughness, is adopted, leading to a NEW modified life prediction model. Study on fatigue model of FV520B-I with surface roughness is a very beneficial effort in fatigue theory and fatigue engineering development.

This work presents the effects of sintering temperature and mechanical milling on the weight loss of the powder metallurgical Fe–28Mn–3Si (wt%) alloy. Mechanically milled (MM) and blended elemental (BE) Fe–28Mn–3Si powder mixtures were prepared. Both the MM and BE compacts were sintered in a vacuum furnace for 3 h at various temperatures. It was found that weight loss occurred among all the sintered compacts. The weight loss of the sintered MM compacts was much lower than their BE counterparts sintered at the same temperature. The weight loss of the compacts was mainly caused by the sublimation of Mn in the Mn depletion region. A single α-Fe phase was observed on the surface of all the sintered samples. Predominant γ-austenite and minor ε-martensite were detected in all the sintered compacts at locations beyond the Mn depletion region. Mn3Si phase was found in BE alloys sintered at 1000 °C.

The metadynamic recrystallization (MDRX) behavior of a Nb–V microalloyed nonquenched and tempered steel was investigated by isothermal hot compression tests on Gleeble-1500 thermal-mechanical simulator. Compression tests were performed using double hit schedules at temperatures of 1273–1423 K, strain rates of 0.01–5 s−1, initial grain sizes of 92–149 μm and an inter-pass time of 0.5–10 s. The experimental results show that MDRX softening fraction increases with the increasing of deformation temperature, strain rate, and inter-pass time, while it decreases with the increasing of initial grain size. Based on the experimental results, the MDRX softening fraction kinetic model and recrystallized grain size model of the tested steel was established. Besides, using the above mathematic models, a finite element model was built to simulate the MDRX process of the tested steel. The simulation results show good agreement with the experimental ones, which indicates that finite element method is an effective approach to analyze the MDRX behavior and the established that mathematic models of the tested steel are reliable and accurate.

The dissimilar metal inert-gas arc welding of aluminum alloy and ultrahigh strength steel was studied. The weld appearance was improved when welding wire was directed toward steel groove middle. The Al–steel joints have welding–brazing characteristics and include weld zone (WZ), bond zone (BZ), and interface zone (IZ). The welds with Al–Mg and Al–Cu welding wires consist of α-Al and β-Al3Mg2, and α-Al and Al2Cu, respectively. The IZ contains needle-like Fe4Al13 and lath-shaped Fe2Al5 layers. With increasing welding current, the interface layer thickness and joint cracking sensibility increased due to enhanced heat input and tensile stress in the joints. They were decreased effectively when using Al–Cu welding wire, as the constituent Cu could restrain the growth of interface layer and lower its hardness and brittleness. In particular, Al–Cu welding wire elevated the tensile strength of the Al-steel joints from 65 MPa for Al–Mg wire to 128 MPa.

In present study, the semi-solid slurry of the AZ91–2Ca–1.5Ce alloy was firstly prepared by gas-bubbling processing and then was formed by die casting and squeeze casting, respectively. The influence of processing parameters on microstructure and mechanical properties of the alloy was investigated. The results show that increase of gas-flow rate and appropriate pouring temperature can improve the quality of the semi-solid slurry and change the morphology of primary α-Mg particles to rosette-like shape or roundness. Meanwhile, the addition of calcium and cerium refines the as-cast microstructure and dramatically improves the tensile properties, also the strengthening phase Al4Ce exists around the grain boundary. The peak ultimate tensile strength (UTS), yield strength, and elongation of rheo-die casting AZ91–2Ca–1.5Ce alloy are 202 MPa, 154 MPa, and 2.3%, respectively. Especially, compared with conventional liquid die-casting, the UTS and elongation of rheo-die casting AZ91–2Ca–1.5Ce alloy were improved by 8% and 64%, respectively. Meanwhile, the rheo-die casting alloy also showed higher mechanical properties than rheo-squeeze casting alloy, since the higher speed that die casting provided could induce more compact microstructure and remain the semi-solid characteristic better.

In this research, the effect of austenitizing at 900–1100 °C and tempering at 250–650 °C on the microstructure and mechanical properties of 410 and 410 Ni martensitic stainless steels was investigated. The transformation of austenite to ferrite surrounded the austenitizing within the temperature range of 900–1050 °C. The grain size and hardness measurements proved that austenitizing at 1050 °C leads to the partial dissolution of carbides without a considerable growth of austenite grains. The mechanical tests showed two peaks in strength and troughs in ductility by tempering at 450 and 650 °C due to the formation of primary and secondary carbides. The better ductility and fracture toughness in 410 Ni, comparing to 410, were attributed to the effect of Ni on stacking fault energy. Fractured surfaces revealed ductile fracture of the samples tempered at low temperatures, e.g., 250 °C. However, after tempering at 450 and 650 °C, 410 showed a brittle fracture and 410 Ni exhibited a dual intergranular-brittle fracture mechanism.