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.

The hydrogenation behavior of Ti–44Al–6Nb (at.%) alloy was studied at temperature range of 1373–1693 K, and the effect of hydrogen on hot deformability was tested on Gleeble-1500D thermo-simulation machine. It is found that the lnCH increases linearly with 1/T, and hydrogen content increases with increasing of hydrogen time and flow rate logarithmically. The positive heat of solution of hydrogen denotes that hydrogen absorption in TiAl alloys is an endothermic reaction. The results also show that hydrogen promotes the lamellar colony size and lamellar spacing because that hydrogen can promote the diffusion of elements. There is more residual B2 phase in the hydrogenated alloy revealing that hydrogen stabilizes the B2 phase during hydrogenation. The nanohardness and elastic modulus of the alloy are decreased from 4.4 and 213.5 GPa to 4.2 and 199.8 GPa after hydrogenation with 0.033 wt% H. Thermal simulation results show that the peak stress is decreased by 30% after hydrogenation with 0.033 wt% H which corresponds to decreasing the deformation temperature by about 50 K. This is attributed to hydrogen-promoted dynamic recrystallization and dislocation movement.

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.

A common characteristic in semiconductor nanostructures is the lattice strain originating from the lattice mismatch between layers of different compositions. Three-dimensional strain measurement in crystals using transmission electron microscopy (TEM) techniques has been the subject of intense works for decades. This information is required for the strain-bandgap engineering being used by our current fast computers and necessary for future quantum computers. However, the missing information was the 3rd dimension that is the atomic displacement and how it changes along the electron-beam direction. The strain information along the electron-beam direction is in the phase of the diffracted beam, which has been obtained recently by the novel technique of self-interference of split higher order Laue zone line (SIS-HOLZ). SIS-HOLZ has been made possible by the correction of the beam aberrations having its analytical and experimental details reported here for the atomic displacement profile existing at the interface of a Si and Si/Si0.8Ge0.2 superlattice.

This study investigated the tribological behaviors of carbon fiber (CF) reinforced epoxy (EP) composites immersed in 10 wt% sulfuric acid solution for different numbers of days. The tribological properties of the composites were evaluated as a function of their different fiber orientations (0°, 45°, 90°, and normal orientation). The CF/EP composites showed a favorable anticorrosion performance, as assessed by electrochemical corrosion tests, due to the tightly stacked CF. Meanwhile, the wear tests indicated that the CF orientation had a significant effect on the tribological performance. Composites with 45° CF orientation exhibited the lowest friction coefficient, whereas those with 90° CF orientation had lowest wear rate, which was 6 times lower than that of composites with normal CF orientation. Moreover, the surface microstructures of the worn surfaces were observed by scanning electron microscopy (SEM) to determine the corresponding wear mechanisms.

The Al–Mg–Sc alloys have become important materials in research conducted on superplasticity in aluminum-based alloys. Many results are now available and this provides an opportunity to examine the consistency of these data and also to make a direct comparison with the predicted rate of flow in conventional superplasticity. Accordingly, all available data were tabulated with divisions according to whether the samples were prepared without processing using severe plastic deformation (SPD) techniques or they were processed using the SPD procedures of equal-channel angular pressing or high-pressure torsion or they were obtained from friction stir processing. It is shown that all results are mutually consistent, the measured superplastic strain rates have no clear dependence on the precise chemical compositions of the alloys, and there is a general agreement, to within less than one order of magnitude of strain rate, with the theoretical prediction for superplastic flow in conventional materials.

Organic molecular crystals are often noncubic and contain significant steric hindrance within their structure to resist dislocation motion. Plastic deformation in these systems can be imparted during processing (tableting and comminution of powders), and the defect density impacts subsequent properties and performance. This study measured the elastic and plastic properties of representative monoclinic, orthorhombic, and triclinic molecular crystalline structures using nanoindentation of as-grown sub-mm single crystals. The variation in modulus due to in-plane rotational orientation, relative to a Berkovich tip, was approximately equal to the variation of a given crystal at a fixed orientation. The onset of plasticity occurs consistently at shear stresses between 1 and 5% of the elastic modulus in all three crystal systems, and the hardness to modulus ratio suggests conventional Berkovich tips do not generate fully self-similar plastic zones in these materials. This provides guidance for mechanical models of tableting, machining, and property assessment of molecular crystals.

We report a novel approach to the instantaneous photoinitiated synthesis of mixed anatase-rutile nanocrystalline TiO2 thin films with a three-dimensional nanostructure through pulsed white light irradiation of photosensitive Ti-organic precursor films. Pulsed photoinitiated pyrolysis accompanied by instantaneous self-assembly and crystallization occurred to form graphitic oxides-coated TiO2 nanograins. Subsequent pulsed light irradiation working as in situ pulsed photothermal treatment improved the crystalline quality of TiO2 film despite its low attenuation of light. The non-radiative recombination of photogenerated electrons and holes in TiO2 nanograins, coupled with inefficient heat dissipation due to low thermal conductivity, produces enough heat to provide the thermodynamic driving force for improving the crystalline quality. The graphitic oxides were reduced by pulsed photothermal treatment and can be completely removed by oxygen plasma cleaning. This photoinitiated nanofabrication technology opens a promising way for the low-cost and high-throughput manufacturing of nanostructured metal oxides as well as TiO2 nanocrystalline thin films.

A method comprising a two-step alkali/acid treatment of poly (vinylidene fluoride) (PVDF) polymer is developed for the fabrication of flat-sheet PVDF membranes functionalized with labile hydroxyl groups. This method involves the application of a short-duration modification in alkali medium (5% KOH). Extensive characterizations were performed on the prepared membranes. Modification of the polymer altered the crystallinity of the PVDF from a mixture of both α and β phases to a predominant β phase. Lower work of adhesion of the modified membrane indicated the formation of a more hydrophobic and wetting-resistant membrane surface. Centrifugation of the polymer dope after the modification had a pronounced impact on the properties of the resultant membranes. This protocol could be utilized in fine-tuning the properties of PVDF membranes for various target-specific applications such as membrane distillation. This method can also be used in functionalizing PVDF membranes further by exploiting the labile –OH group present on the membrane surface.

Cu–FeS composites without lead were prepared by power metallurgy process. The friction and wear properties were examined on a “block-on-ring” testing machine under dry sliding conditions with and without oil immersion. Results showed that both the frictional coefficient and the wear volumes decreased with increased FeS content in the composite under dry sliding conditions. In the condition of dry friction without oil immersion, the FeS solid lubricating film formed and played a role of antifriction and adhesion resistance. Under the dry friction condition with oil immersion, the lubricant oil stored in the porous FeS layer precipitated to the surface to form the oil film, which could work together to achieve a liquid–solid synergistic lubrication with the FeS transfer film. The lubrication performance of the collaborative lubrication reaction is better than that of the solid transfer film. With the increase of FeS, the collaborative lubrication became more obvious.

(Ti,Mo)Al/Al2O3 composites were successfully synthesized utilizing in situ reactive hot pressing method with Ti, Al, and MoO3 powders as starting materials. A possible synthesis mechanism was proposed to explain the formation of (Ti,Mo)Al/Al2O3 composites. The investigation results indicate a probable reaction process that molten Al reacted with MoO3 to form Al2O3 and Mo, and the TiAl matrix grains were refined increasingly by Al2O3 with the addition of MoO3 increased, accompanying with a small quantity of Mo containing phase AlMoTi2 formed in the fabricated composites. Meanwhile, the microstructure and mechanical properties of the (Ti,Mo)Al/Al2O3 composites were characterized. The as-synthesized composites exhibited lamellar structure of TiAl intermetallic compound and the in situ formed fine Al2O3 particles dispersed at the stratified TiAl matrix grain boundaries hindering the growth of the grain size of the matrix. And the Rockwell hardness, flexural strength, and fracture toughness of the as-prepared (Ti,Mo)Al/Al2O3 composite were 44.08 HRC, 684 MPa, 7.63 MPa·m1/2, which improved by 57.4%, 107.3%, and 38.7% compared to monolithic TiAl, respectively. The reinforcing mechanism of the material was also discussed.

In this study, chitin was deposited on AZ91 magnesium alloy at room temperature for 180 min, and then HA coating was applied as second layer for 180, 240, 300, 360, and 420 min by dipping method. The layers were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission-scanning electron microscopy (FE-SEM), as well as adhesion, nanohardness, and potentiodynamic polarization tests. XRD results analyzed by Williamson–Hall method revealed residual tensile and compressive strains in the chitin and HA coatings, respectively and with prolonged deposition time to 420 min, coating adhesion decreased. FTIR results indicated the presence of the chemical factors affecting the chitin and HA coatings. FE-SEM results indicated that prolonged deposition time resulted in increased coating density and formation of a porous structure of HA coating. Overall, the optimum corrosion resistance was observed for the sample with 300 min deposition time.

Complex wrought magnesium-based alloys suffer from poor ductility, strong yield asymmetry, and lower than desired fatigue performance. These unfavourable properties are exacerbated by the heterogeneity of the microstructure and strong texture forming in Mg alloys during conventional thermo-mechanical processing. For the user, severe plastic deformation (SPD) increases flexibility in tailoring the microstructures and selecting the properties to be emphasized in wrought Mg alloys. The effect of SPD by hot multiaxial forging and equal channel angular pressing on the formation of fine grain microstructure and on resultant mechanical properties is discussed. It is demonstrated that SPD is capable of substantial enhancement in ductility and tensile strength which gives rise to concurrent improvement of both low- and high-cycle fatigue properties. The main message of this overview is that the full potential for improving fatigue performance of Mg alloys can be taken advantage of by way of comprehensive understanding the role of the individual effects associated with the SPD-induced microstructures and textures.

Super-black carbon aerogel sleeves (CAS) with different reflectivities and a clear aperture had been made, by the sol–gel polycondensation of resorcinol (R) and formaldehyde (F) under the catalysis of sodium carbonate (C), and was used to eliminate stray light. We explained that the subwavelength structure is the main factor that leads to the low reflectivity of CA and constructed a simple optical system to measure the exit power from CAS in different directions. We proved that different CASs have different matting effects, and all of these CASs have better matting effects than that of monolithic graphite that has higher reflectivity. To show the fine angular resolution ability of CAS, we measured the faculae from the reflected light of a compact disc and found that the CAS with a clear aperture of 1.0 mm is the best. The super-black CAS could be used in precision optical instruments and to eliminate stray light in the optical.

Shape memory alloys (SMAs) are unique class of smart materials with excellent physical, mechanical and biomedical properties, which have wide applications in several fields such as aerospace, robotics, biomedical, and dental etc. These alloys are well known for exhibiting shape memory effect (SME) and pseudoelasticity (PE), it is a well-established fact that they are required to be processed into functioning parts. The conventional machining affects the internal properties of shape memory alloys and hence, it is reported that nonconventional machining techniques are more suitable. Wire electro discharge machining (WEDM) is one of the nonconventional machining processes for machining complicated shapes without hampering the internal properties of such type of materials. In the present experimental investigation, wire electro discharge machining of Ti50Ni40Co10 shape memory alloy (SMA) has been carried out and machining performances such as surface roughness (SR), and material removal rate (MRR) have been evaluated. Experimental results exposed that pulse on time, pulse off time and servo voltages are most influential process parameters on the responses. The machined surface has been characterised with respect to microstructure, microhardness, and phases formed.

Single-stranded DNA molecules capable of molecular recognition and catalysis can now be routinely generated via the technique of in vitro selection. When coupled with adequate signal transduction modes, these synthetic functional DNA species represent a potential paradigm shift in the research and development of biosensors to meet the challenges of our rapidly changing world. Coupling functional DNA molecules with graphene materials for the design of optical biosensors has become an exciting research area in recent years, mostly because graphene materials are not only excellent quenchers of fluorescence, but they also display considerably different affinities for free and ligand-bound functional DNA molecules. We will discuss notable progress in this area in this mini-review by highlighting representative studies.

Highly porous and fully crystalline mullite fiber compacts were fabricated by uniaxial hot pressing of stacked short-fiber mats without binders or sintering aids. The special feature of this new fabrication method is the use of MAFTEC® organic bound mat (OBM) type fiber mats consisting of semicrystalline “MLS-2” short fibers. In contrast to conventional polycrystalline mullite fibers, semicrystalline MLS-2 fibers consist of amorphous silica and nanoscale transitional alumina. Due to this special microstructure, MLS-2 fibers are less prone to fiber breakage upon shear load and therefore can well withstand pressure-assisted consolidation. Hot pressing of stacked OBM to highly porous fiber compacts is facilitated by the thermally driven softening of amorphous silica above 900 °C; favorable deformation and consolidation rates are achieved above 1050 °C. Above 1250 °C the mullite is crystallized at the expense of amorphous silica and simultaneously both deformation and consolidation comes to an end. Obtained MAFTEC OBM-derived fiber compacts consist only of crystalline mullites, and therefore mechanical properties are favorably retained at high temperatures.

A major obstacle in the organic solar cell field is the inability to predict the relevant microstructural length scales that determine charge transport of the interpenetrating polymer/small molecule network based on the component chemical structures. This has led to a trial-and-error approach, which is extremely labor-intensive. This manuscript is our attempt to move toward forming a link between small molecule chemical structure and the morphological hierarchy of the blend. We focus on geometric motifs of small molecule organic semiconductors which have 2D, nonspherical 3D, and quasispherical 3D molecular orbital extent. We find that phase separation in these blends is a function of the molecular structure, and that the small molecule chemical structure is coupled to the crystallite orientation distribution of the polymer matrix. We further find that the ability of a molecule to form a network with a well-defined length scale of phase separation depends on the polymer persistence length.

Self-assembled oxide-based vertically aligned nanocomposite (VAN) thin films have aroused tremendous research interest in the past decade. The interest arises from the range of unique nanostructured films which can form and the multifunctionality arising from these forms. Hence, a large number of oxide VAN systems have been demonstrated and explored for enhancing specific physical properties, such as strain-enhanced ferroelectricity, tunable magnetotransport, and novel electrical/ionic transport properties. The epitaxial growth of the nanocomposite thin films and the coupling at the heterogeneous interfaces are critical considerations for future device applications. In this review, the advantages of strain coupling along vertical interfaces and film-substrate interfaces in nanocomposite films over conventional single phase films are discussed. Specifically, a unique strain compensation model enabling the epitaxial growth of two-phase nanocomposites having large lattice mismatch with substrates is proposed. Out-of-plane strain coupling between the two phases is also discussed in terms of designing strain states for desired functionalities.

Ultrasonic vibration can lead to significant load reduction in metal forming, and this concept has been widely applied in microforming. Recently, we discovered that low-frequency mechanical vibration (less than 100 Hz) with micro-amplitudes also features the same effects. In this study, low-frequency vibration-assisted tensile deformation experiments were conducted on commercially low-carbon steel. Effects of vibration softening and residual softening were obtained during experiments. Both these softening effects became prominent at high vibration amplitudes. Detailed microstructural analyses reveal that a low-frequency vibration treatment altered the interior characteristics of the metal. Electron backscatter diffraction results showed low-angle grain boundaries, and the interior misorientation angle increased greatly with the application of a low-frequency vibration. Changes in the microstructure became more pronounced with the rise of vibration amplitudes. Instantaneous stress reduction results from the additional energy applied in the form of vibration, which lowers the barrier energy for the dislocation motion. The residual softening effect can be interpreted via a dislocation density decrease as a result of vibration markedly improving the opportunity for dislocation annihilation or stacking.