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TiSiCN composite coatings with different C contents were prepared on Cr buffer layer by plasma‐enhanced magnetron sputtering. The structure, composition, surface, and cross‐sectional morphology of the coatings were characterized by X‐ray photoelectron spectroscopy, X‐ray diffraction, Raman spectroscopy, scanning electron microscope, and atomic force microscope. The hardness, elastic modulus, and tribological performance of the coatings were evaluated by nanoindentation and reciprocating friction tests. The results showed that the TiSiCN composite coatings are amorphous structure composed of TiCN compound and microcrystalline graphite, and amorphous phases. The increase of C content changed the content and distribution of TiCN ceramics nanocrystal, amorphous Si3N4 and amorphous carbon (sp3‐ and sp2‐hybridized C), thus affecting the hardness and friction behavior of the coatings. The hardness of the composite coatings was related to the content of TiCN phase and sp3‐C in the coatings. The TiSiCN composite coating with C content of 68.2% had lower coefficient of friction and the lowest wear rate. [ABSTRACT FROM AUTHOR]

This study investigates the synergistic effect of SiCp on grain refinement and dispersion hardening in Al matrix composites produced by ball milling followed by hot rolling. Al grains are effectively refined by generating significant dislocations and subsequent dynamic recrystallization during milling. The presence of SiCp stimulates the grain refinement process by more effectively reducing the grain size to ∼40 nm. Furthermore, an increase in the milling speed and duration reduces the grain size and improves the dispersion of SiCp, thereby enhancing the yield strength without any significant loss of ductility. Consequently, SiCp/Al composites exhibit a tensile strength of 430.27 MPa with more than 4% of elongation before failure, indicating a strength enhancement of ∼325% compared to the unmilled pure Al counterpart. [ABSTRACT FROM AUTHOR]

Producing bulk AlN with grain sizes in the nano regime and measuring its thermal conductivity is an important milestone in the development of materials for high energy optical applications. We present the synthesis and subsequent densification of nano-AlN powder to produce bulk nanocrystalline AlN. The nanopowder is synthesized by converting transition alumina (δ-Al2O3) with

Magnesium alloys, as the lightest structural alloys, provide the possibility of solving environmental problems by improving energy efficiency. Developing and maintaining nanocrystalline matrix is a huge challenge, and the key to achieving ultra-high strength. The nanocrystalline Ti/AZ61 composite prepared by hot pressing was annealed, and its microstructural evolution was characterized via SEM, XRD, and TEM, including the changes in magnesium matrix, Ti dispersions, and nano-scale precipitates. The density and mechanical properties of annealed composites were tested and analyzed. After annealing treatment at 623 K for 80 h, the average grain size of nanocrystalline Ti/AZ61 composites was 102 nm. 97% of Ti dispersions were submicron sized, and Ti3Al precipitates remained nanometer-sized. Ti dispersions and Ti3Al precipitates were uniformly distributed in the magnesium matrix. Compared with hot pressed composites, the crack that originated from the prior particle boundary (PPB) was restrained for annealed composites. The improved density and PPB bonding strength of annealed Ti/AZ61 composites had a positive impact on strength and plasticity. After annealing treatment for 40 h, the density increased from ∼2.041 g/cm3 to 2.066 g/cm3. The hardness, yield strength, and FFS were 146 HV, 493 MPa, and 5.6%, respectively, with corresponding increasing rates of 7%, 12%, and 65%, respectively.

Spinel type nano ferrite compound MgFe2O4 was synthesized through sol gel technique using metal nitrates as precursors. The phase composition, morphology and elemental analysis of magnesium ferrite (MgFe2O4) were performed by X-ray diffraction, fourier transform infrared, atomic force microscopy, energy dispersive x-ray and scanning electron microscopy, analyses. The sample's X-ray diffraction pattern verifies the existence of single phase material, with the size of its crystallites estimated to be 39.9 nm. Fourier transform infrared examination supported metal-oxygen vibrations corresponding to tetrahedral and octahedral sites, respectively. From scanning electron microscopy image, grain size obtained about 97.7 nm. Raman spectra of the sample shows five Raman active modes (A1g + Eg + 3F2g), which is compatible with the spinel structure. Magnetic measurement study at room temperature shows a hysteresis loop behaviour with a low saturation magnetization value, 27.192 emu g-1 and a small coercivity value. The optical band gap determined using UV-visible transmittance spectra. Additionally, X-ray photoelectron spectroscopy are used to confirm oxidation states and explore the chemical composition of the sample.

Investigation the structural and magnetic properties of nanocrystalline Co78Zr17B2Si1W2 alloy during melt spinning and annealing processes were the main goal of this study. In this regard, samples were prepared using vacuum induction melting, melt spinning and subsequent annealing. The specimens were evaluated using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). Based on results, nanocrystalline Co5Zr single phase with hard magnetic properties (Ms=29.5 emu/g and Hc=2.7 kOe) successfully formed during melt spinning process (at wheel speed of 40 m.s-1). The coercivity value of rapid solidified sample increased to about 3.2 kOe during annealing process up to 400°C. However, more increasing in annealing temperature lead to the transformation of non-equilibrium magnetic Co5Zr phase to stable Zr2Co11 phase, which has distractive effects on final magnetic properties.

The evolution of the microstructure and mechanical properties of a vacuum arc melted non-equiatomic Al0.4Co0.5V0.2FeNi high-entropy alloy (HEA) subjected to severe plastic deformation was investigated experimentally and by simulations. The present work explored duplex HEAs, comprising a face-centered cubic (FCC) matrix and a body-centered cubic (BCC) phase, towards outstanding their mechanical responses. The Al0.4Co0.5V0.2FeNi alloys had a duplex structure, i.e., with dispersed B2-phase islands (with sizes of dozens of microns) in several hundred micron-, even millimeter-sized FCC grains. The mechanical properties of this HEA were strongly deformation dependent, i.e., when deformation increased from 30 % up to 60 %, the yield strength and ultimate strength tensile increased from ∼0.9 GPa and 1.0 GPa to ∼1.2 GPa and 1.3 GPa, respectively. During tensile deformation, initial fractures occurred in the FCC phase located close to the interface between the FCC and BCC phases. With an increase of deformation, the fracture degree in the FCC phase got larger, and fractures also appeared in the BCC phase. Combined with the geometric dislocation density calculation results from an electron backscatter diffraction (EBSD) analysis, it can be seen that the dislocation density near the phase interface of FCC was higher, making it more likely to produce defects.

In the present study, nanocrystalline gradient cemented carbide with an average grain size of only 155 nm in tungsten carbide (WC) was prepared using V(C, N), and its sintering behavior was investigated. Scanning electron microscopy (SEM) and electro probe micro-analysis (EPMA) revealed that V(C, N) promotes the formation of a cubic carbide free layer (CCFL) and effectively suppresses the WC grains in the nanocrystal range at different sintering temperatures and holding times compared with Ti(C, N). The gradient cemented carbide had the highest hardness (2169 kg/mm2), the highest fracture toughness (11.94 MPa/m2), and the lowest friction coefficient (0.22) and wear resistance when the sintering temperature was 1400 °C and the holding time was 60 min. In addition, the cobalt (Co)-poor phenomenon occurred in the CCFL of the gradient cemented carbide, which was mainly related to the small radius of the capillaries in the nanocrystals. [ABSTRACT FROM AUTHOR]

High-entropy materials have exhibited excellent catalytic performance due to the rich defects and active sites brought about by the random distribution of individual elements. In the paper, the spinel (CrMnFeCoCu)3O4 high-entropy oxide (HEO) nanoparticles were synthesized by a coprecipitation method followed by calcination. The results showed that the (CrMnFeCoCu)3O4 HEO exhibited high crystallinity with a spinel structure and nanoparticle sizes of 30–50 nm. Meanwhile, the diversification chemical valence and richer oxygen vacancies in (CrMnFeCoCu)3O4 HEO were confirmed, which was attributed to the adjustable electronic structure by the variable chemical valence of adjacent elements in (CrMnFeCoCu)3O4 HEO. The (CrMnFeCoCu)3O4 HEO presented a higher oxygen evolution reaction catalytic activity with a lower overpotential of 313 mV at a current density of 10 mA·cm–2 than that of CuFe2O4 (402 mV) and superior long-term durability with a 89.7% current retention rate after testing for 24 h. The excellent catalytic performance of (CrMnFeCoCu)3O4 HEO could be attributed to the self-regulating electronic structure of multiple elements and richer oxygen vacancies in the HEO. These findings promote the HEO as a candidate material for electrocatalytic application. [ABSTRACT FROM AUTHOR]

Mn doped nanocrystalline PbS thin films were deposited onto glass substrates by chemical bath deposition (CBD) method. All the deposited thin films were found to be crystalline having cubic phase structure. The optical properties of the Mn doped nanocrystalline PbS thin films have been studied. They have high absorbance in the UV-visible region. The linear nature of (αhv)² vs (hv) plots of PbS thin films confirmed that the transition is direct and the optical band gap energy of PbS films is found to increase from 1.90 eV to 2.28 eV with decreasing crystallite size from 21 nm to 11 nm and the optical band gap values are higher than the bulk value (0.40 eV). The optical band gap of Mn doped PbS films are found to increase with increase in dopant concentrations. The Photoconductive rise time and decay time determined from the prepared films are found to decrease with increase in doping concentrations. [ABSTRACT FROM AUTHOR]

Two thermal barrier coating (TBC) systems comprising NiCoCrAlY bond coat onto a second-generation Ni-based single crystal superalloy and nanostructured 4 mol% Y2O3-stabilized ZrO2 (4YSZ) and conventional yttria-stabilized zirconia (YSZ) top coats upwardly were deposited by approaches of arc ion plating (AIP) and air plasma spray (APS). As indicted by the experimental results, the 4YSZ TBCs exhibited superior thermal cycling resistance compared with conventional YSZ TBCs at 1100 °C. The 4YSZ top coat exhibited higher toughness due to its intrinsic property of nanocrystalline structure, homogeneously distributed and diverse directions of pores and preexisted cracks. The cracks and spallation in 4YSZ TBCs occurred at the interface of top coat and thermally grown oxide (TGO) layer. Instead, the crack initiation and propagation started along the lamellar interface in the top coat of conventional YSZ TBCs, leading to the rapid crack bridging and subsequent spalling of top coat. Additionally, before and after oxidation, the 4YSZ top coat showed higher hardness compared to conventional YSZ top coat. Degradation mechanism and distribution of residual stress in TGO for the 4YSZ TBCs were investigated in the current study. [ABSTRACT FROM AUTHOR]

Three-dimensional nanocrystalline Ag–C composites containing a hexagonal diamond structure were produced by electrochemical reduction of acetic acid and electrodeposition of Ag-(NO3) (0.01 M) at −1.1 V vs Ag/AgCl at ambient conditions. After applying the negative potential, an ultrathin layer of Ag (<0.1 μm) was first deposited, and subsequently, competitive electrodeposition of Ag and electroreduction of acetic acid resulted in the formation of nanocrystalline Ag–C products on the electrodes. A combination of microscopic, structural, and spectroscopic characterization results reveals that the nanocrystalline Ag–C contains a hexagonal diamond structure with an average crystallite size of 26 nm. The nanodiamond phase remained unchanged throughout 15–140 min reaction time. However, increasing the reaction time, the thickness of nanocrystalline Ag–C films increased to ∼2 μm with some large polyhedra carbon structures. The nanocrystalline Ag–C composites were utilized in the casting process of sterling silver to enhance its antitarnish properties. The antitarnishing of sterling silver upon exposure to a H2S environment was significantly improved by 50% with 0.005 wt % loading of the Ag–C composite. [ABSTRACT FROM AUTHOR]

Fair green emission is observed in the Er3+ activated Ca9Bi(VO4)7 nanocrystalline material series fabricated via solution combustion methodology. A crystal prototype of the trigonal phase with R3c (161) space group having irregularly shaped grains with sizes between 43 and 61 nm is formed. Morphological aspects are examined via scanning and transmission electron microscopy (SEM and TEM). On near-UV excitation, the photoluminescence spectrum presents a good green emission at 18182 cm−1 wavenumbers consistent with the electronic transition 4S3/2→4I15/2. The energy transfer phenomena are also discussed. The highest luminous intensity is observed for 8.0 mol% of Er3+ composition (synthesized via solution combustion technique) with 382 nm excitation. d–q Exchanges authorized the presence of the concentration quenching phenomenon. Time decay analysis and non-radiative energy transfer mechanisms were also explored. Diffuse reflectance spectroscopy was taken into use to explore the energy bandgap, which lies in the semiconductor domain. The CIE coordinates lay in the greenish zone of the chromaticity plan, thus confirming their latent contention in pc-WLEDs and other innovative optoelectronic claims. [ABSTRACT FROM AUTHOR]

Vanadium-based hydrogen storage alloys have been widely investigated; however, alloys in the cast state are typically coarse-grained. In this study, an as-cast V 45 Fe 15 Ti 20 Cr 20 medium-entropy alloy was prepared by arc melting, and microstructural analysis revealed that the alloy was composed of nanocrystals. The initial pretreatment temperature of the alloy was approximately 100 K lower than that of the as-cast coarse-grained alloy. At room temperature, the time required for the alloy to reach 90% saturation was only 140 s, indicating excellent hydrogen absorption kinetics. The alloy is fully activated after two hydrogen absorption/desorption cycles. The phase transformation of the alloy in the early hydrogenation stage was investigated using X-ray diffraction, and the results showed that the BCC phase was completely transformed into the BCT phase when hydrogen uptake was performed for 6 s. Furthermore, the apparent activation energy of dehydrogenation in the present alloy calculated using the Kissinger method was 69.8 ± 0.8 kJ/mol. The pressure-composition-isotherms tests showed that the hydrogen absorption capacity of the alloy at 295 K was 2.12 wt%. The hydrogenation/dehydrogenation enthalpy change of the alloy was calculated by the Van't Hoff equation, which was 30.90 ± 1.47 and 33.95 ± 0.41 kJ/mol, respectively. The present work demonstrates that nanostructured vanadium-based hydrogen storage alloys can be fabricated using traditional casting techniques. Our study also enriches the understanding of the microstructures of medium-entropy alloys, which may provide positive guidance for the design of novel vanadium-based hydrogen storage alloys. • An as-cast V-based medium entropy alloy has a nano-scale microstructure. • Nanostructured alloys have very good kinetic properties at room temperature. • The phase transformations during absorption were studied. [ABSTRACT FROM AUTHOR]

Aluminium (Al) alloys are known for their high strength and good ductility, making them materials of choice in many aerospace and transport industries. However, they tend to yield to failure in practice as a result of localized corrosion including stress corrosion cracking, exfoliation corrosion, intergranular corrosion, and pitting corrosion. The formation of gradient-structured layers through several severe plastic deformation methods and heat treatments/coatings are the leading possible means of addressing their present shortcomings. The present work reviews the practical ways by which the aforementioned localized corrosion in Al alloys can be reduced to the minimum if not totally eradicated. The corrosion properties of severely plastic-deformed Al alloys obtained via different routes including ultrasonic shot peening, equal-channel angular processing, constrained groove pressing, among others, were extensively reviewed and summarized. The corrosion mechanisms as well as the factors responsible for the improvement or deterioration in corrosion resistance of Al alloys after surface modification were discussed, and the prospects and research trends for future developments are summarized. [ABSTRACT FROM AUTHOR]

In this work, vanadate-fluorapatite, V2O5/Ca10(PO4)6F2, nanocrystals were successfully synthesized through a straightforward one-step co-precipitation method. This method was based on two toxic solid wastes, which are mainly generated as by-products during sulfuric acid manufacturing and in the phosphate industry. The two solid wastes were mainly based on phosphogypsum as a source of calcium and vanadium pentoxide as a source of vanadate. In comparison to numerous conventional methods for FAP synthesis, this innovative method is not laborious, not complex, cost-effective, and environmentally friendly, thanks to the recovery of toxic solid wastes. Furthermore, it consists of mixing various contents of anhydrous gypsum with phosphoric acid, vanadium pentoxide, and ammonium fluoride at one time and at room temperature with no further adjustment of the pH. Several physicochemical characterization techniques were used, including X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Ultraviolet-Visible Spectroscopy (UV-vis). Whereas SEM analysis of the crystals obtained showed a nanometer-scale fluorapatite crystallites was obtained. The obtained results offer exciting potential for applying the prepared nanomaterial in both photocatalysis and pollution removal. They hold great promise and are expected to generate significant interest in these fields. [ABSTRACT FROM AUTHOR]

The La0.88Sr0.12MnO3 nanocrystalline is synthesized by sol-gel chemical method, shows a typical paramagnetic-ferromagnetic phase transition at 280 K. A thorough study on critical behavior analysis of magnetization isotherms is performed by various techniques such as modified Arrott plot, Kouvel-Fisher method, and critical isotherm analysis. Based on these methods, the accurate critical exponents (β = 0.5936(2) and γ = 1.0928(6)) are determined. Both critical exponents (β and γ) have been confirmed to fulfill the Widom scaling relation δ = 1+ γ β . Moreover, these exponents also obey the single scaling equation of H M δ = h ( ε H 1 / β ) . The obtained critical exponents are closer to the theoretical prediction of mean-field model but shows a slight deviation from theoretical values. We proposed that this deviation is due to the inherent disorder effect as the dimension of La0.88Sr0.12MnO3 particles reduced to nanoscale. Highlight: La0.88Sr0.12MnO3 nanocrystalline is prepared by the sol-gel method. The critical properties associated with the ferromagnetic transition are investigated by various techniques. The critical exponents show a slight deviation from theoretical values due to the inherent disorder effect when the La0.88Sr0.12MnO3 particles reduced to nanoscale. [ABSTRACT FROM AUTHOR]

NiTi shape memory alloys have been widely explored because of their superelasticity. However, the application of conventional coarsed NiTi SMAs is limited by low superelastic stress and poor superelastic stability due to their low yield strength. In this study, nanocrystalline (NC) Ni47Ti50Fe3 alloy with average size is ∼15 nm was obtained by large deformation cold drawing and low temperature annealing. After ten cycles of loading (up to 6%)-unloading, the NC Ni47Ti50Fe3 alloy exhibited a high superelastic stress (1170 MPa)，low areduction rate of superelastic stress (12%) and small residual strain (0.66%). This overall performance is better than that of previous NiTi-based SMAs. We have suggested that this mainly stems from the synergistic reinforcement combines Fe element doping and high-density grain boundary.

Cu-Sn alloys have been known as bronze since ancient times and widely used as electrode materials, ornaments, tableware and musical instruments. Cu-22Sn alloy fabrication by hot forging process is a Korean traditional forged high-tin bronze. The tin content is 22 percent, which is more than twice that of bronze ware traditionally used in China and the West. Copper and tin have a carbon solubility of several ppm at room temperature, making Cu-Sn-C alloys difficult to manufacture by conventional casting methods. Research on the production of carbon-added copper alloys has used a manufacturing method that is different from the conventional casting method. In this study, Cu-22Sn-xC alloy was fabricated by mechanical alloying and spark plasma sintering. The carbon solubility was confirmed in Cu-Sn alloy through mechanical alloying. The lattice parameter increased from A0 to C2, and then decreased from C4. The microstructural characteristics of sintered alloys were determined using X-ray diffraction and microscopic analysis. As a result of comparing the hardness of Cu-22Sn alloys manufactured by conventional rolling, casting, and forging and Cu-22Sn-xC alloy by sintered powder metallugy, B0 sintered alloy was the highest at about 110.9 HRB.

The austenitic stability and strain-induced martensitic transformation behavior of a nanocrystalline FeNiCrMoC alloy were investigated. The alloy was fabricated by high-energy ball milling and spark plasma sintering. The phase fraction and grain size were measured using X-ray diffraction. The grain sizes of the milled powder and the sintered alloy were confirmed to be on the order of several nanometers. The variation in the austenite fraction according to compressive deformation was measured, and the austenite stability and strain-induced martensitic transformation behavior were calculated. The hardness was measured to evaluate the mechanical properties according to compression deformation, which confirmed that the hardness increased to 64.03 HRC when compressed up to 30%.

In this paper, the microstructure evolution and thermal stability of nanocrystalline (NC) AZ31-2.5 wt%VP magnesium matrix composites were studied, while the hardness was analyzed. The results showed that the NC AZ31-2.5 wt%VP still kept NC scale after annealing at 300 °C and 350 °C. Even at 400 °C and 450 °C, the grain size of the annealed composite only grew to 113 nm and 132 nm, which was still in ultrafine grain scale, illustrating excellent thermal stability of NC AZ31-2.5 wt%VP. Furthermore, the V particles, which was uniformly distributed in the Mg matrix, had no obvious change in dimension after annealing, while it also had no new phase formed. The stabilization mechanism was expounded and found that the pinning effect of V particles effectively inhibited the grain growth of Mg matrix at high temperature. In addition, the grain growth kinetics equation (D6−D06=kt) was utilized to explain the grain growth behavior of NC AZ31-2.5 wt%VP, and the activation energy (Ea) of grain growth was calculated to be 130.9 kJ/mol, which was much higher than that of pure Mg (92 kJ/mol). Eventually, the hardness of NC AZ31-2.5 wt%VP was contrastive studied and the hardness evolution curves at different temperatures were obtained. After annealing treatment was performed at 450 °C for 180min, the hardness remained at 80 HV, which was higher than that of as-cast AZ31 (53 HV).

Introduction: Otomycosis is the common infection of ear caused by fungus generallyfound in tropical and subtropical countries where hot and humid conditions assist these types of infections. Also, the recurrence rate of these infections is high and there is limited therapeutic options,which makes its management challenging. The purpose of our study was to determine the antifungal properties of nanocrystalline silveron patients with otomycosis.Materials and Methods:The study was carried out in Pune (India) at the Dr. D.Y. Patil Medical college, Hospital and research centre in the department of Ear Nose Throat & Head over a period of one year (2019 -2020). Our study constitutes 100 patients,(58 male and 42 female),with clinicallydiagnosed otomycosis were treated using nanocrystalline silver gel soaked Gelfoam. Results: The Patients which were included in our study were in theage group of 18 to 60 years with highest prevalence in male (58%) aged 30 to 45 years.There were a greater number of cases of infection coming to the hospitali.e., 62 casesduring wet season compare to dry season which were 38 cases. Most common fungus encountered belonged to genus Aspergillus (55%) followed by Candida (45%). 89% of the patients (70% within 5 to 6 days and 19% from 7 to 14 days) symptomatically improved.Conclusion: Use of Nanocrystalline silver cured most of the patients (89%) within 14 days. Treating Otomycosis patients with Nanocrystalline silver showed beneficial results. Study with large sample should be conducted to validate the benefits of Nanocrystalline silver

Nanocrystalline (NC) magnesium alloys and composites present potential for improving energy efficiency in transportation applications due to outstanding strength. Unfortunately, softening owing to grain growth at elevated temperature would induce fatal invalidity. The NC SiCp/AZ91 composite was isothermally annealed. A study on the thermal stability, including phase transformation, grain growth, softening, and strengthening mechanisms was carried out. After annealing treatment at 673 K for 240 min, the average grain size of AZ91-15vol.%SiCp composite increased from 29.0 nm to 53.1 nm. Coherent interface between nano-scale Mg17Al12 precipitates and Mg matrix was certified by HRTEM. Pinning effect due to the dispersing submicron SiC particles with size of 164 nm and nano-scale Mg17Al12 precipitates and dragging effect due to dissolving Al element were the reasons for excellent thermal stability. After annealing treatment, the hardness values of AZ91-xvol.%SiCp (x = 5, 10 and 15) composites were 1.61 GPa, 1.48 GPa and 1.78 GPa. Taking annealed AZ91-15vol.%SiCp composite as an example, there was no evident softening phenomenon and the decreasing ratio was ∼2% in comparison with milled composite with hardness of 1.82 GPa. Non-thermal sensitive SiC particles and high thermal stability Mg matrix played a key role in non-softening of composites.

Thermal stability and mechanical property of the multicomponent nanocrystalline Fe–ZrNbMoTa alloys were investigated. Single-phase nanocrystalline Fe–(ZrNbMoTa)x (x = 0.1, 0.2, 0.5 and 1 at. %) alloys were prepared by ball milling and followed by annealing in a set of predesigned condition. It was found that the Fe-based multicomponent alloys possess good thermal stability through 10 h annealing at 900 °C, which is attributed to the thermodynamics effect in the reduction of grain boundary energy caused by multicomponent co-segregation of Zr, Nb, Mo and Ta, and kinetics effect related to sluggish diffusion and Zener pinning of a small amount of second-phase precipitation. Additionally, nanocrystalline Fe–(ZrNbMoTa)x alloys show excellent mechanical properties. The hardness is 738.6 HV, and its yield strength and compressive strength reach up to 3100 MPa and 3600 MPa, respectively. These are attributed to the comprehensive effects of nanocrystalline, solid solution and second phase strengthening.

CdS quantum dots sensitized TiO2 nanocrystalline photoanode was developed on conducting FTO substrates which act as working electrode in photoelectrochemical cells. Deposition process was conducted by applying ionic layer adsorption and SILAR process. The thickness of CdS quantum dots (QDs) are maintained by cycles of SILAR. The morphology and nature of TiO2/CdS photoanodes are characterized by XRD, UV–Vis., IR, PL, TEM and EDS analysis. XRD patterns indicate the presence of anatase TiO2 and CdS in TiO2/CdS quantum dots thin film (5 and 10 cycles) samples with crystallite size 11.19 nm. The optical band gap energies are 3.10, 3.05 and 2.78 eV for TiO2, TiO2/CdS quantum dots (5 and 10 cycles), respectively. The band gap energy of TiO2 found to be decreases with the sensitization of CdS quantum dots. The images of HR-TEM confirm the formation of a heterostructure between TiO2 and CdS quantum dots. The PEC performance for TiO2/CdS photoanode was analyzed using a 500 W tungsten lamp with light intensity of 30 mW/cm2 in the electrolyte iodide/polyiodide as a redox couple (0.5 M). CdS quantum dots sensitized TiO2 film as a photoanode for solar cells produces good power conversion efficiency of 1.32 and 3.52% for 5 and 10 cycles respectively. [ABSTRACT FROM AUTHOR]

The traditional NiTi alloy has been widely used in many fields due to its superelasticity, shape memory effect and excellent bio compatibility. For example, it has been prepared into orthodontic arch wire and vascular stent in the biomedical field. However, biomedical equipment needs precision and miniaturization, and the traditional NiTi alloy has been unable to keep up with the development. The nanocrystalline NiTi alloy after severe plastic deformation has better tensile, compressive strength, plasticity and fatigue properties than the traditional coarse and ultra-fine grained NiTi alloy. Tt is expected to expand the scope of application in the biomedical field. Nanocrystalline NiTi alloy can be used in the manufacture of new medical devices and orthopedic bio--materials. The combination of NiTiAg with Ag not only has excellent mechanical properties, but also has antibacterial effect. W-NiTi composite material is formed by combining with W nanowire/belt to improve the radiation opacity and make the positioning and deployment of instruments and implants in the human body easier. Tn recent years, there is also a new surface modification technology, ultrasonic nanocrystalline surface modification, which produces nanocrystalline on the surface of NiTi alloy to improve fatigue and corrosion resistance. This paper mainly introduces the application of existing NiTi alloys and the application prospect of nanocrystalline NiTi alloys in biomedical field. [ABSTRACT FROM AUTHOR]

Graphene, a single atomic layer of graphitic carbon, has attracted much attention because of its outstanding properties hold great promise for a wide range of technological applications. Large‐area graphene films (GFs) grown by chemical vapor deposition (CVD) are highly desirable for both investigating their intrinsic properties and realizing their practical applications. However, the presence of grain boundaries (GBs) has significant impacts on their properties and related applications. According to the different grain sizes, GFs can be divided into polycrystalline, single‐crystal, and nanocrystalline films. In the past decade, considerable progress has been made in engineering the grain sizes of GFs by modifying the CVD processes or developing some new growth approaches. The key strategies involve controlling the nucleation density, growth rate, and grain orientation. This review aims to provide a comprehensive description of grain size engineering research of GFs. The main strategies and underlying growth mechanisms of CVD‐grown large‐area GFs with nanocrystalline, polycrystalline, and single‐crystal structures are summarized, in which the advantages and limitations are highlighted. In addition, the scaling law of physical properties in electricity, mechanics, and thermology as a function of grain sizes are briefly discussed. Finally, the perspectives for challenges and future development in this area are also presented. [ABSTRACT FROM AUTHOR]

Mechanical testing at small length scales has traditionally been resource‐intensive due to difficulties with meticulous sample preparation, exacting load alignments, and precision measurements. Microscale fatigue testing can be particularly challenging due to the time‐intensive, tedious repetition of single fatigue experiments. To mitigate these challenges, this work presents a new methodology for the high‐throughput fatigue testing of thin films at the microscale. This methodology features a microelectromechanical systems‐based Si carrier that can support the simultaneous and independent fatigue testing of an array of samples. To demonstrate this new technique, the microscale fatigue behavior of nanocrystalline Al is efficiently characterized via this Si carrier and automated fatigue testing with in situ scanning electron microscopy. This methodology reduces the total testing time by an order of magnitude, and the high‐throughput fatigue results highlight the stochastic nature of the microscale fatigue response. This manuscript also discusses how this initial capability can be adapted to accommodate more samples, different materials, new geometries, and other loading modes. [ABSTRACT FROM AUTHOR]

With the increasing demand for smaller, lighter, and more affordable electromagnetic devices, there is a growing trend toward developing high-power-density transformers and electrical machines. While increasing the operating frequency is a straightforward approach to achieving high power density, it can lead to significant power loss within a limited volume, resulting in excessive temperature rise and device degradation. Therefore, it is crucial to design high-power-density electromagnetic devices that exhibit low power loss and efficient thermal dissipation to address these challenges. Advanced techniques, such as the utilization of novel and advanced electromagnetic materials, hold great promise for overcoming these issues. Specifically, nanocrystalline and amorphous magnetic materials have emerged as highly effective solutions for reducing power loss and increasing efficiency in electromagnetic devices. This paper aims to provide an overview of the application of nanocrystalline and amorphous magnetic materials in transformers and electrical machines, along with key technologies and the major challenges involved. [ABSTRACT FROM AUTHOR]

Recovery of cold worked metals is associated with a loss of strength due to the reduction of the defect density. However, already in the 1960s analytical models and few experiments suggested that this may not generally be the case and even a hardening rather than a softening might occur. With the availability of severe plastic deformation and deposition techniques this anneal hardening phenomenon has been observed frequently. In this overview we summarize early findings on this topic before focusing on general observations and potential origins, with a special focus to show the similarities for nanostructures across different grain size scales (i.e., structures prepared by deposition and severe plastic deformation techniques, respectively). Comparison of different results indicate a grain size dependent hardening increment that could be additionally affected by segregation or the processing variables. Considering the agreement of the peak hardening temperatures with that for dislocation annihilation at grain boundaries, anneal hardening can be rationalized by the loss of intragranular defects and grain boundary relaxation. Grain boundary diffusivity hence plays a crucial role and particular solutes could amplify the hardening process even further. As anneal hardening already occurs for grain sizes at the micron scale, its effect on properties is even of technological relevance. Beneficial effects on the fatigue strength are evident, but the strain softening of anneal hardened specimens drastically shorten ductility. Nevertheless, some strategies to overcome this adverse effect seem promising to create metallic structures with exceptional combinations of strength and ductility. [ABSTRACT FROM AUTHOR]

One of the problems hindering the commercial application of metallic Mg is its poor kinetics performance of hydrogen absorption and desorption. At present, the mechanical activation process has exhibited excellent potential for improving the hydrogen storage kinetic performance of magnesium hydride. Herein, the high-energy ball-milling method was used to improve the kinetics by generating nanocrystalline structures inside Mg metals and changing the surface state of the Mg particles. Significantly, mechanical activation treatment greatly improves the first hydrogenation/dehydrogenation kinetic properties. Experimental results showed that after 120 min of milling, only 330 min are needed to absorb 7.3 wt% of hydrogen, which is 9 times faster than the 3176 min needed for untreated material. The time needed to release all of the hydrogens is therefore 12 times faster. A unique activation mechanism formed layered structure and nanocrystalline during the mechanical milling process, which promoted hydrogen dissociation on the particle surface and diffusion along the layer interfaces and grain boundaries. [ABSTRACT FROM AUTHOR]

Molybdenum oxide (MoO3) electrochromic (EC) materials have not been widely used at present due to relatively poor performance and inadequate research. In order to enhance the EC properties of the MoO3 to achieve the purpose of practical use, the modified nanocrystalline MoO3 films were fabricated by a cheap and simple complexation-assisted sol–gel method followed by annealing at 300 °C. In this method, dopamine (DA) is used as a structure-directing agent and the added amount of DA has a great influence on the structure and morphology and, thus, electrochemical and EC properties of the MoO3 films. Different from the pure MoO3 polycrystalline film, the film modified with a suitable amount of DA possesses a distinctive nanocrystal-embedded amorphous structure, and, thus, can achieve synergy effects of EC properties through combining the advantages of both amorphous phases and nanocrystalline. Therefore, compared with the pure MoO3 film, the modified MoO3 film shows much higher EC properties in terms of optical contrast, coloration efficiency, switching speed, and cycling stability. Moreover, a complementary type EC device with dual active layers (the modified MoO3 film and polyaniline) was fabricated and tested, and the results demonstrate the potential application of the modified MoO3 film. [ABSTRACT FROM AUTHOR]

This study investigates the impact of current density on the microstructure, composition, and internal stress of Ni-W alloys electrodeposited in a citrate system. Using XRD, SEM, EDS, TEM, and XPS, it was found that tungsten serves as a solute in a Ni-W FCC structure oriented in the (111) direction. Increasing current density led to higher tungsten content and current efficiency. The addition of 2-Butyne-1,4-diol altered the carbon content, significantly reducing internal stress by promoting carbide formation near grain boundaries, which prevented coating shrinkage during hydrogen escape. This carbon enrichment improved the alloy's corrosion resistance. [ABSTRACT FROM AUTHOR]

In this study, sodium citrate (SC) ions were applied as a complexing agent in the co-deposition of CuZn alloy thin film coatings from nontoxic sulphate electrolyte at room temperature. This study examined the effects of SC ion concentrations on morphology, electrical resistivity, and structure of the deposited thin films. Using the cyclic voltammetry method, electrochemical analyzes were performed. It was seen in the results of XRD analyzes that merely α and/or β phases were formed in the CuZn thin-film coatings. Average grain sizes, estimated by Scherrer's formula, were decreased 63% via the addition of SC to the bath. Electrical resistivity properties of electrodeposited CuZn alloys were realized at a wide range temperature between 100 to 405 K. It is seen that when the amount of SC in the electrolyte increases, it decreases the amount of copper in the film, increases the amount of zinc, and increases the electrical resistance of the film. [ABSTRACT FROM AUTHOR]

Double perovskite La 2 MnCoO 6 (LMCO) nanoparticles have been synthesized by a molten salt method and used as promising catalysts for electro-chemical hydrogen evolution reactions (HERs). An average size of LMCO nanoparticles was estimated approximately 65 nm from electron microscopy. LMCO nanoparticles crystallize in a monoclinic structure (space group of P 2 1 / n). The refined lattice constants of " a" = 5.5038(2) Å, " b" = 5.4462(4) Å, " c" = 7.7547(4) Å, and " β" = 90.050(3)°. LMCO nanoparticles exhibit promising catalytic performances for electro-chemical HERs with a low Tafel slope value (190 mV/dec). The onset over-potential for HERs was found to be approximately 120 mV, which is in good agreement with the reported onset over-potentials of other electro-catalysts for HER. The stability tests confirm that the electrode materials are stable and efficient electro-catalysts for HERs. This is noteworthy that the double perovskites are recognized as promising alternates for precious electro-catalysts. [ABSTRACT FROM AUTHOR]

The investigation of the structural and magnetic properties of nanocrystalline Co78Zr17B2Si1W2 alloy during melt spinning and annealing processes were the main goals of this study. In this regard, samples were prepared using vacuum induction melting, melt spinning and subsequent annealing. The specimens were evaluated using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). Based upon the results obtained, nano-crystalline Co5Zr single phase with hard magnetic properties (Ms= 29.5 emu/g and Hc= 2.7 kOe) was formed during melt spinning process (at wheel speed of 40 m.s-1). The coercivity value of rapidly solidified sample increased to about 3.2 kOe during annealing process up to 400°C. However, higher annealing temperature led to the transformation of non-equilibrium magnetic Co5Zr phase to a more stable Zr2Co11 phase, which has negative effects on final magnetic properties. [ABSTRACT FROM AUTHOR]

Ferrite nanoparticles are an emerging material for industrial and biomedical applications. Herein, a simple non-aqueous sol–gel method is used to synthesize CuxZn(1-x)Fe2O4 (x = 0.0, 0.25, 0.5, and 0.75) nanoparticles. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis spectroscopy, and a vibrating-sample magnetometer (VSM) were utilized to investigate the structural formation and magnetic merits of the prepared ferrite nanoparticles. The Rietveld refinement of the X-ray diffraction pattern confirmed the formation of single-phase cubic structures with Fd3¯m space groups for all samples. The increase in cu2+ concentration in zinc ferrite nanoparticles decreases the lattice parameters from 8.4418 to 8.4368. The energy gap of cu2+-doped zinc ferrite increases from 1.89 to 2.04 eV with a decrease in particle size. MH loop revealed an increase in Ms and Mr Parameters as Hc reduces with an increase in Cu2+ concentration in the zinc ferrite matrix. It was discovered that an increase in Cu2+ content improved the antibacterial activities of Cu2+-doped zinc ferrite against all bacterial species.

In this research, CoFeNi thick films were prepared through the electrodeposition process from a natural pH bath containing the complex agent of sodium citrate. By increasing applied current density, there is a transition from BCC (Fe) phase to BCC (Fe) + FCC (Co) phases and then to FCC (Co) phase. The XRD pattern showed a nanocrystalline structure for the CoFeNi thick films which was further confirmed by the TEM images. The magnetic properties of the synthesized magnetic films exhibit a noticeable decrease in the coercivity by decreasing the crystallite size which is consistent with the “D6” law. The resistivity of the CoFeNi thick films increased by decreasing the grain size which is due to the scattering of the charge carriers. The increase in the applied current density results in the gradual substitution of the iron atoms in CoFeNi films by nickel atoms leading to a reduction in saturation magnetization.

The isothermal oxidation behavior of multi-component high entropy alloys (HEAs), namely AlCuCrFeMn, AlCuCrFeMnW0.05, AlCuCrFeMnW0.1, and AlCuCrFeMnW0.5, was investigated and the behavior of the oxide layer was analyzed. All four HEAs were synthesized via mechanical alloying (MA) and consolidated by spark plasma sintering (SPS). The samples were oxidized in the air atmosphere at a temperature of 500 °C for 50 h. Based on the thermogravimetric result, the oxidation rate of the materials decreased with the increase of W content, and the values of parabolic constants were on a level similar to those observed in Ni–Al superalloys. However, higher content of W improves the continuity and internal position of the WO3 scale, which leads to increased oxidation resistance. Throughout the oxidation process, the composition of the phases of all materials changed significantly. The triple-thick oxide layer formed of Al2O3, Cr2O3, and WO3, developed in HEAs, has been carefully studied using the XPS technique.