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The effects of the sintering holding time and cooling rate on the microstructure and mechanical properties of nanocrystalline Fe-Cr-C alloy were investigated. Nanocrystalline Fe-1.5Cr-1C (wt.%) alloy was fabricated by mechanical alloying and spark plasma sintering. Different process conditions were applied to fabricate the sintered samples. The phase fraction and grain size were measured using X-ray powder diffraction and confirmed by electron backscatter diffraction. The stability and volume fraction of the austenite phase, which could affect the mechanical properties of the Fe-based alloy, were calculated using an empirical equation. The sample names consist of a number and a letter, which correspond to the holding time and cooling method, respectively. For the 0A, 0W, 10A, and 10W samples, the volume fraction was measured at 5.56, 44.95, 6.15, and 61.44 vol.%. To evaluate the mechanical properties, the hardness of 0A, 0W, 10A, and 10W samples were measured as 44.6, 63.1, 42.5, and 53.8 HRC. These results show that there is a difference in carbon diffusion and solubility depending on the sintering holding time and cooling rate.

A series of compositionally complex A 2 Zr 2 O 7 nanocrystalline ceramics were successfully prepared using sol-gel and co-precipitation methods. The resultant ceramics possess a cubic defect fluorite structure, with the sol-gel method yielding an average grain size of approximately 50–70 nm, while the co-precipitation method result in an average grain size of about 40–60 nm. Leaching tests revealed that the smaller grain sizes are correlated with higher leaching rates. Furthermore, for ceramics with similar grain sizes, those with higher entropy values exhibited higher leaching rates. The increase in grain boundaries was found to reduce the leaching performance of the rare earth zirconate ceramics, and this effect became more pronounced with increasing entropy. This work provides insights into the selection of entropy values and grain sizes for the high-level radioactive waste matrices, which can be considered as a potential substrate for the simultaneous immobilization of multiple radionuclides. [ABSTRACT FROM AUTHOR]

This investigation focused on the thermal stability of nanocrystalline (NC) binary and ternary Ni-Y-Zr alloys synthesized through ball-milling. The microstructural changes following annealing, conducted up to 1200 °C, were studied using various techniques, including X-ray-line-broadening, micro-hardness, and transmission electron microscopy. The results revealed that the rate of grain growth observed in the Ni-Y-Zr ternary alloy at 600 °C resembled that in pure NC-Ni at 100 °C. Moreover, the Ni-1.4Y-1.1Zr ternary system exhibited a maximum hardness of 753 HV (average) at 600 °C, which was approximately 60 HV higher than the Ni-1.2Y/1.9Y and Ni-1.5Zr/2.7Zr binary alloys and more than double that of pure NC-Ni for similar grain sizes. These characteristics were linked to the formation of nano-sized oxides and nitrides of Y and Zr within the microstructure. In summary, this study emphasizes the notable high-temperature microstructure stability of Ni-based ternary alloys, attributed to the additive effects of Y and Zr. Due to this extended stability, this ternary system could find potential applications at elevated temperatures in areas such as jet engine turbine blades and power plants. • Impact of Y and Zr on the microstructural stability of Ni was investigated. • Ni-Y-Zr ternary system shows enhanced hardness. • Grain growth rate in Ni-Y-Zr at 600 °C resembles pure NC-Ni at 100 °C. [ABSTRACT FROM AUTHOR]

Digital Image correlation (DIC) is routinely applied using optical and scanning electron microscopy methods to map local strains during deformation. In this letter, we report its use for in-situ TEM imaged deformation evolution for a nanocrystalline metal. Since transmitted electrons give rise to complex contrast conditions, with such contrast associated with the mechanisms of deformation, one can track these changes if particular care is done in image analysis and interpretation. We describe these methodologies to enable this correlation through frame averaging. Using these collective correlation conditions, we found that the average DIC strain matches well with the far field strain values yielding increased confidence in its application. Through the utilization of DIC in the TEM, nanoscale deformation mechanisms can be further elucidated because of the increased spatial resolution offered by TEM. [Display omitted] [ABSTRACT FROM AUTHOR]

The energetics of triple lines are often negligible in polycrystalline systems, but may play a significant role in the finest nanocrystals, and in fact lower the excess defect energies of those polycrystals. This paper develops a methodology to assess polycrystalline average grain boundary and triple junction excess energies for pure fcc metals Ni, Cu, Al, Pd, Pt, Ag and Au using embedded atom method potentials. It is found that there are correlations between the triple line energy and physical quantities such as grain boundary and dislocation line energy, but with a negative sign indicating that triple junctions reduce intergranular excess energy per area on average. The relationship with grain boundary energy is of order ∼−4.5 × 10−10 m, and the triple junction energy is about −1/12 of the dislocation line energy. Despite their low energy, triple junctions can significantly affect total system energy due to their high density in the finest nanocrystals; for example, 6-nm Pd nanocrystals have an effective intergranular energy of ∼0.83 J/m2 (compared with the large grain size limit of 0.93 J/m2), translating to a measurable bulk excess enthalpy of ∼6 kJ/mol. Such excess enthalpy is experimentally assessable, and the present framework can be used to measure triple junction energies. For instance, re-analyzing data of Lu and Sun (Phil. Mag., 1997) we obtain grain boundary and triple junction energies of 0.33 J/m2 and −3.0 × 10−10 J/m respectively for Selenium nanocrystals, which can be compared with modeled values of 0.76 J/m2 and −1.02 × 10−10 J/m by using our method with a published bond-order potential for Se. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper reports on the use of high-power impulse magnetron sputtering to deposit Cu-based nano-multilayer films (CuZrTiAl) on Si wafers and AISI 304 stainless steel. Co-sputtering can be performed using multiple simultaneous targets to decrease the cost of manufacturing alloy targets at industrial scales. Co-sputtering mode allows variations in the power supplied to the various targets to control the intensity of the plasma jets and thereby tailor the composition of the deposited films. Our primary aim in this study was to elucidate the effects of Al target power (from 0.3 to 1.3 kW) on the structure and antibacterial properties of the resulting coatings. Varying the Al target power was shown to alter the chemical composition, layer thickness, and structure. EPMA results revealed that increasing the power from 0.3 to 1.3 kW caused a monotonic increase in Al content from 6.1 to 18.3 at%. Dark-field TEM images revealed that decreasing the period thickness from 8.6 to 4.6 nm caused the ultra-thin film Cu to transform into a single isolated nano-crystal, which facilitated the release of Cu ions to improve antibacterial effects (from 84 % to 99 % for Escherichia coli). This study also demonstrated the recycling of the proposed Cu-based nanoscale multilayer films to fabricate metal-doped ZnO nanowires for use in photodetectors. The photodetector achieved a photocurrent-to-dark-current ratio of 150 when using an LED light source with a wavelength of 365 nm. • The period thickness from 8.6 to 4.6 nm caused the Cu layer to transform into isolated nano-crystals. • Nanocrystals facilitated the release of copper ions and reduced the distance to the surface. • The Cu-based nano-scale multilayer coatings as a replacement for metal nitrates. • To achieve the SDGs, Cu-based nano-scale multilayer coatings were recycled to create ZnO NWs for photodetectors. [ABSTRACT FROM AUTHOR]

A heterogeneous micro/nano multilayered (HM/NMed) Al/Al-0.5 wt %Cu composite, composed of alternating coarse-grained pure Al layers and nanostructured Al-0.5 wt %Cu alloy layers containing a nanolamellar structure (NLS) with lamellar thickness as small as ∼60 nm, was developed by accumulative roll bonding (ARB) followed by low temperature annealing. Deformation induced Cu atoms grain boundary (GB) segregation was observed in Al-0.5 wt %Cu layer, which is responsible for the formation and stabilization of the NLS in the Al-0.5 wt %Cu alloy layers. This resultant HM/NMed Al/Al-0.5 wt %Cu composite with dramatic difference in microstructure and strength/hardness between neighboring pure Al and Al-0.5 wt %Cu alloy layers can achieve an exceptional strength-ductility combination: a yield strength close to the NLSed Al-0.5 wt %Cu alloy, and a tensile ductility comparable to coarse-grained pure Al. Strong hetero-deformation-induced (HDI) strengthening associated with the activation of stacking faults, are responsible for this exceptional strength-ductility synergy. The results presented here demonstrate a general design strategy based on solute GB segregation that enables the fabrication of HM/NMed Al-based materials with multi-scale hierarchical microstructures and improved mechanical properties. • A specially designed heterogeneous micro/nano laminated structure (HM/NLS) was developed in Al alloys. • This HM/NLS is composed of alternating coarse-grained pure Al layers and nano-lamellar-structured Al-0.5 wt %Cu alloy layers. • The HM/NLSed Al/Al-0.5 wt %Cu composite produce an exceptional strength-ductility combination. • Strong HDI strengthening associated with the activation of SFs is responsible for the exceptional strength-ductility synergy. [ABSTRACT FROM AUTHOR]

The photoresponse properties of nanocrystalline tin dioxide (SnO 2) thin films with different grain sizes were systematically studied for fabricating transparent oxide-based ultraviolet (UV) photodetector. SnO 2 nanoparticles were synthesized using the coprecipitation method and calcination temperatures were varied (400 °C–800 °C) to prepare SnO 2 particles of different grain sizes (∼8 nm–∼42 nm). Subsequently, thin films of SnO 2 nanoparticles were deposited using the spin-coating technique to fabricate UV photodetectors. The optical transparency of SnO 2 thin films was improved by 10 % with the increasing grain size of the sample, while the band gap of the films was found to vary from 3.718 eV to 3.761 eV. The responsivity (R λ) and the external quantum efficiency (EQE) of SnO 2 based photodetector were noticeably large (R λ = 200 mA/W and EQE = 90 %) in the UV range for devices with the smallest grain sizes (∼8 nm). Moreover, the same device exhibited a much faster photoresponse time (∼2 s) and a large photo-to-dark current ratio (∼103). The structural and spectroscopic studies on the SnO 2 thin films revealed that the microscopic parameters like grain size, grain boundary potential, and surface oxygen vacancies play significant roles in modulating the optical properties and photoresponse of the nanocrystalline SnO 2 thin films. [Display omitted] • SnO 2 thin films were prepared by varying nanocrystallite sizes in solution method. • Optical transparency of SnO 2 films was modulated up to 10 % with varying grain size. • UV photodetectors, fabricated on SnO 2 films, exhibited large ON-OFF ratio of ∼103. • SnO 2 photodetectors exhibited ∼200 mA/W responisvity with ∼90 % quantum efficiency. • Grain size and surface oxygen vacancies have a crucial role behind the observed results. [ABSTRACT FROM AUTHOR]

Multi-component nitride thin films usually show high hardness and good wear resistance due to the nanoscale structure and solid-solution strengthening effect. However, the state of N atoms in the thin film and its effects on the compressive strength is still unclear. In this work, (AlTiVCr)N multi-component nitride thin films with a face-centered cubic (FCC) structure prepared by the direct current magnetron sputtering method exhibit a superior strength of ~4.5 GPa and final fracture at a strain of ~5.0%. The excellent mechanical properties are attributed to the synergistic effects of the nanocrystalline structure, covalent bonding between N and metal atoms, and interstitial strengthening. Our results could provide an intensive understanding of the relationship between microstructure and mechanical performances for multi-component nitride thin films, which may promote their applications in micro- and nano-devices. [ABSTRACT FROM AUTHOR]

Pulsed laser deposition (PLD) is a commonly utilized technology for growing thin films in academia and industry. Compared to alternative deposition processes, the PLD offers more excellent benefits such as adaptability, control over the growth rate, stoichiometric transfer, and an infinite degree of freedom in the ablation geometry. This investigation collected data from five reputable academic databases, including Science Direct, IEEE Xplore, Scopus, Web of Science, and Google Scholar. In this review, we analyzed and summarized 20 empiricals on the impact of pulsed laser deposition on the production nanostructure, including laser wavelength, laser fluence, repetition rate and pulse length of the laser pulse, pulse shaping of the laser spot, plasma generation, distance between substrates and target, angular position of the material, substrate temperature, gas composition, and target material properties. Finally, we show this field's advantages, challenges, and viewpoints and focus on the strengths and weaknesses that can improve the deposition of nanostructure properties for various applications. Therefore, provide fascinating insights into the interaction of these processes in different fields. [ABSTRACT FROM AUTHOR]

An equiatomic low-activated FeCrV ternary alloy was prepared by mechanical alloying and spark plasma sintering. The BCC solid solution alloy exhibited an excellent strength-ductility synergy properties, which was 1.85 ​GPa compressive yield strength, 3.04 ​GPa fracture strength and more than 28% plasticity at room temperature. Even at an elevated temperature of 600 ​°C, its yield strength was still more than 1 ​GPa, revealing a pronounced high temperature resistance. The FeCrV alloy had a homogeneous microstructure with high-density dislocations. A nanocrystalline characteristic was demonstrated and the average grain size was about 322 ​nm, leading to the improved mechanical properties. The strengthening mechanism was discussed in detail and the contributions of strengthening factors were calculated. The FeCrV alloy was irradiated up to 160 dpa with 2 ​MeV Au2+ ions at 573 ​K. The nanoindentation test was carried out to simply evaluate the hardening degree under such a high dose irradiation with heavy ions. The semi-quantitative analysis results show that FeCrV alloy has an excellent irradiation tolerance compared with pure Fe. [Display omitted] • Nanocrystalline multi-component FeCrV ternary alloy was fabricated by mechanical alloying and spark plasma sintering methods. • The improved mechanical properties were obtained and the excellent irradiation resistance is also demonstrated. • The outstanding mechanical performance is mainly ascribed to the dislocation and grain boundary strengthening. [ABSTRACT FROM AUTHOR]

3.4 Influence of EUG content on dynamic mechanical properties of NBR/EUG composites The DMA curves of NBR/EUG composites with different EUG contents are showed in the Figure 3(a) and (b). 3.3 Influence of EUG content on mechanical properties of NBR/EUG composites The mechanical properties of NBR/EUG composites with different contents of EUG are depicted in Figure 2. Graph: Figure 1: Logarithmic modulus of NBR/EUG composites with different contents: (a) NBR/EUG = 95/5; (b) NBR/EUG = 90/10; (c) NBR/EUG = 85/15; (d) NBR/EUG = 80/20. 4 Conclusions After adding EUG into NBR, EUG is uniformly dispersed in NBR in the form of nanocrystallites, forming NBR/EUG nanocomposite. [Extracted from the article]

In a wireless power transfer (WPT) system, in order to reduce the leakage of the magnetic field in the space and to improve the transmission efficiency of the system, a magnetic shielding mechanism is usually added to the coupling coil. However, the commonly used ferrite material has defects of brittleness, easy cracking, and a low saturation limit. Therefore, a novel magnetic shielding mechanism based on a quartz fiber and nanocrystalline reinforced resin matrix composite material was proposed, and epoxy resin and cross-laminate-splicing processes were used to improve the resistivity of the nanocrystalline material and to improve the eddy current loss. A discretized geometric model was designed for quartz fiber, and the effects of different shielding structures on the space magnetic field and the power loss were simulated and analyzed. In the experiment, a space magnetic field measurement system was built, and the transmission efficiency was analyzed. The results showed that the new magnetic shielding mechanism has a good shielding effect, can effectively suppress leakage of the magnetic field in space, reduce the weight, and improve the mechanical performance while also achieving a high transmission efficiency of 85.6%. [ABSTRACT FROM AUTHOR]

In this work, the thermal stability of nanocrystalline (NC) AZ31/TiB2 magnesium matrix composites was investigated, while the microstructure evolution and mechanical properties were analyzed. The results indicated the AZ31/TiB2 still maintained NC structure after annealing at 350 °C for 180 min. Even at the high annealing temperature of 400 °C and 450 °C for 180 min, their average grain size just reached about 124 nm and 155 nm, indicating excellent thermal stability. The TiB2 particles with sub-micron size uniformly distributed in Mg matrix had no change in size and no reaction with matrix during the annealing treatment. Due to the strong Zener pinning effect of TiB2 particles, the grain growth of Mg matrix at high temperature was effectively inhibited. Meanwhile, the solution and precipitation behavior of Al atoms were completed in a short time, due to the existence of many grain boundaries and structural defects. By calculation, the grain growth kinetics was described by the kinetics equation D 8 - D 0 8 = k t and the activation energy Eg for grain growth was 131.6 kJ/mol, which was much higher than that of pure Mg (92 kJ/mol). Due to their excellent thermal stability, the decrease in both compressive yield strength and ultimate compressive strength was no more than 12.2% after annealing treatment. Even annealing at 450 °C for 180 min, the CYS and UCS of the samples were still above 283 MPa and 295 MPa, respectively. [ABSTRACT FROM AUTHOR]

The ball milling technique has been extensively used to prepare different metastable states with nanocrystalline microstructures from intermetallic compounds. In the present manuscript, the authors have systematically investigated the structural and electronic properties of a series of mechanically alloyed Fe1 – xAlx (0.3 ≤ x ≤ 0.6) samples using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The ball milling process causes the formation of solid-state reactions that are aided by severe plastic deformation, resulting in reduced crystallite size and interesting microstructural and electronic changes in the resulting system. The TEM results show that the crystallite size decreases to the nanometer range (between 6-8 nm) as a function of x and the metals dissolve at the nanograin boundaries. As a result of nanometric dimensions, the reactivity increases as a result of the increased surface-to-volume ratio, which leads to the FeAl alloy phase formation. The XPS survey scan shows that the samples do not have any major contamination, and the core level spectra show a slight shift of Fe2p and Al2p peaks toward higher binding energy (BE), which proves that different Fe- and Al-rich phases of FeAl alloy have formed after 5 h of milling. [ABSTRACT FROM AUTHOR]

Helium bubbles are known to form in nuclear reactor structural components when displacement damage occurs in conjunction with helium exposure and/or transmutation. If left unchecked, bubble production can cause swelling, blistering, and embrittlement, all of which substantially degrade materials and—moreover—diminish mechanical properties. On the mission to produce more robust materials, nanocrystalline (NC) metals show great potential and are postulated to exhibit superior radiation resistance due to their high defect and particle sink densities; however, much is still unknown about the mechanisms of defect evolution in these systems under extreme conditions. Here, the performances of NC nickel (Ni) and iron (Fe) are investigated under helium bombardment via transmission electron microscopy (TEM). Bubble density statistics are measured as a function of grain size in specimens implanted under similar conditions. While the overall trends revealed an increase in bubble density up to saturation in both samples, bubble density in Fe was over 300% greater than in Ni. To interrogate the kinetics of helium diffusion and trapping, a rate theory model is developed that substantiates that helium is more readily captured within grains in helium-vacancy complexes in NC Fe, whereas helium is more prone to traversing the grain matrices and migrating to GBs in NC Ni. Our results suggest that (1) grain boundaries can affect bubble swelling in grain matrices significantly and can have a dominant effect over crystal structure, and (2) an NC-Ni-based material can yield superior resistance to irradiation-induced bubble growth compared to an NC-Fe-based material and exhibits high potential for use in extreme environments where swelling due to He bubble formation is of significant concern. [ABSTRACT FROM AUTHOR]

Marine industries and environments is faced with corrosion and wear of materials challenge which have shortened the life span of metals and alloys. In order to curb these problems, nanocrystalline coatings of less than 100 nm size range grain refinement have shown better superior properties as substitute for coating mild steel in marine environment. The study aim at using nanocrystalline coatings for structural and corrosion mitigation of mild steel for manufacturing system. The impact of the particle loading in electrolytic bath is fabricated using electrodeposition technique. The coating characteristics were characterized by scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). The microhardness properties and corrosion behaviour was examined through Dura scan diamond-base Vickers hardness tester and Potentiostat Galvanostat (PGStat101) respectively. From the experimental results, the developed coating Ni–Zn–P–30Al2O3 possesses outstanding properties compared to other emerged alloys. The minimum abrasive wear behaviour and maximum hardness property was observed to be 0.022 and 260 HVN respectively with microhardness tester and CERT UMT-2 reciprocating sliding. The potentiodynamic polarization and SEM studies indicated the impact of different loading of Al2O3 as a suitable additive as protective layer over mild steel. This produced coating has better resistance properties to deterioration and can be considered as potential replacement to other nanocrystalline coating towards mild steel protection in manufacturing environment. [ABSTRACT FROM AUTHOR]

Heterogeneous nanostructured metals are emerging strategies for achieving both high strength and ductility, which are particularly attractive for high entropy alloys (HEAs) to combine the synergistic enhancements from multielement composition, grain boundaries, and heterogeneity effects. However, the construction of heterogeneous nanostructured HEAs remains elusive and can involve delicate processes that are not practically scalable. Herein we report using composition design (i.e., enthalpy engineering) to create hierarchical, nanostructured HEAs as demonstrated by adding Ni into FeCrCoAlTi0.5 HEA. The strong enthalpic interaction between (Ni,Co) and (Al,Ti) pairs in FeCrCoAlTi0.5Nix (x = 0.5–1.5) induced phase partitions into B2 (ordered phase, hard) matrix and A2 (disordered phase, soft) precipitates, resulting in a hierarchical structure of B2 grains and sub-grains of near-coherent A2 nanodomains (∼ 12.5 nm) divided by A2 interdendritic regions. As a result, the FeCrCoAlTi0.5Ni1.5 HEA with this unique hierarchical nanostructure exhibits the best combination of strength and plasticity, i.e., a 2-fold increase in compressive strength (2.60 GPa) and significant enhancement of plastic strain (15.8%) as compared with the original FeCrCoAlTi0.5 HEA. Enthalpy analysis and simulation study reveal the phase partition process during cooling induced by an enthalpy-driven order-disorder transition while the order parameters illustrate the strong ordering in (Ni,Co)(Al,Ti)-rich B2 phase and high entropy mixing in less interactive FeCrCo-rich A2 phase. Our work therefore provides a strategy for hierarchical nanostructured HEA formation by composition design considering enthalpy and entropy interplay. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of grain boundaries on the mechanical response in the micrometer and submicrometer levels, complementary experiments and molecular dynamics simulations were conducted on a model bcc metal, tantalum. Microscale pillar experiments (diameters of 1 and 2 μm) with a grain size of ~100–200 nm revealed a mechanical response characterized by a yield stress of ~1500 MPa. The hardening of the structure is reflected in the increase in the flow stress to 1700 MPa at a strain of ~0.35. Molecular dynamics simulations were conducted for nanocrystalline tantalum with grain sizes in the range of 20–50 nm and pillar diameters in the same range. The yield stress was approximately 6000 MPa for all specimens and the maximum of the stress–strain curves occurred at a strain of 0.07. Beyond that strain, the material softened because of its inability to store dislocations. The experimental results did not show a significant size dependence of yield stress on pillar diameter (equal to 1 and 2 um), which is attributed to the high ratio between pillar diameter and grain size (~10–20). This behavior is quite different from that in monocrystalline specimens where dislocation ‘starvation’ leads to a significant size dependence of strength. The ultrafine grains exhibit clear ‘pancaking’ upon being plastically deformed, with an increase in dislocation density. The plastic deformation is much more localized for the single crystals than for the nanocrystalline specimens, an observation made in both modeling and experiments. In the molecular dynamics simulations, the ratio of pillar diameter (20–50 nm) to grain size was in the range 0.2–2, and a much greater dependence of yield stress to pillar diameter was observed. A critical result from this work is the demonstration that the important parameter in establishing the overall deformation is the ratio between the grain size and pillar diameter; it governs the deformation mode, as well as surface sources and sinks, which are only important when the grain size is of the same order as the pillar diameter.

In this study, a preparation route of Co–Cu alloys with soft magnetic properties by high-pressure torsion deformation is introduced. Nanocrystalline, supersaturated single-phase microstructures are obtained after deformation of Co–Cu alloys, which are prepared from an initial powder mixture with Co-contents above 70 wt.%. Isochronal annealing treatments up to 400 °C further reveal a remarkable microstructural stability. Only at 600 °C, the supersaturated phase decomposes into two fcc-phases. The coercivity, measured by SQUID as a function of annealing temperature, remains significantly below the value for bulk-Co in all states investigated. In order to understand the measured magnetic properties in detail, a quantitative analysis of the magnetic microstructure is carried out by magnetic force microscopy and correlated to the observed changes in coercivity. Our results show that the rising coercivity can be explained by a magnetic hardening effect occurring in context with spinodal decomposition.

A novel titanium-based alloy with low density, high hardness, and corrosion resistance was manufactured and characterized in this paper. The Ti60Ni9Fe8Co8Si15 alloy was created from its elemental components and subjected to further manufacturing. To reach a homogeneous phase, the samples were broken into small pieces and were repeatedly re-melted with arc-melting. This base alloy was further processed to manufacture an amorphous/nanocrystalline material by ball milling followed by high-pressure torsion (HPT). For subsequent characterization, X-ray diffraction (XRD), pycnometer densitometry, scanning electron microscopy (SEM) with X-ray energy dispersive spectroscopy (EDS), and hardness measurements were performed. X-ray diffractometry confirmed the formation of a amorphous/nanocrystalline structure, as most of the characteristic peaks related to the crystalline phase disappeared or flattened after ball milling. In accordance, the hardness of the manufactured samples increased by nearly 50 HV compared to the base alloy. The density of the final alloy was measured to be 4.125 g/cm3, with a hardness of 762 ± 39 HV, which confirms that an exceptionally light and, at the same time, hard material was manufactured. In order to distinguish the effects of elemental composition and manufacturing on the measured properties of our alloy, a similar Ti-based alloy with a different elemental composition (Ti47Cu40Zr7.5Fe2.5Sn2Si1) was also prepared with the same proposed manufacturing process. This reference composition resulted in significantly lower hardness (489 ± 31 HV) at a significantly higher density (5.767 g/cm3).

Background: A significant bone defect is a condition wherein the bone cannot repair spontaneously. Therefore, replacing bone defects with bone substitution remains a reconstructive concern for orthopaedic surgeons. Bone Graft Substitution (BGS) are classified broadly, such as bone grafts (autograft, allograft, and xenograft) synthetic ceramics (hydroxyapatite, calcium sulphate). This study aims to determine the effect of various Bone Graft Substitute on the healing process of bone defects assessed based on the area of callus formation and levels of alkaline phosphatase (ALP). Methods: The study design was an in vivo laboratory experimental approach with a randomized post-test only control group design. The 36 experimental animals that matched the inclusion criteria were divided into five groups, in each one of control positive group, one of control negative group, and three of treatment group. The bone graft substitution used in this study is a synthetic ceramic, namely Synthetic HA-Ca10(PO4)6(OH)2 - BONGROS ®, Bone Graft Substitution Nanocrystalline HA-CaSO4-PEROSSAL ®, and also hydroxyapatite Bovine. After selecting rats, we performed osteotomy on the femur to the made bone defect. After 30 days, murine models were harvested. Then, we measure callus formation using radiological examination and ALP level serum Results: From Callus formation, Nanocrystalline HA-CaSO4 is the highest (86.54 ± 4.24604) compared with other groups and significantly (p:0.021) increase in callus formation than the other experimental groups. Then, from the ALP level, Bovine is the highest (9.287 ± 0.58586) but did not significantly compare with K-neg, and the second one is Nanocrystalline HA-CaSO4 higher than KP-1, and it has a significantly higher levels serum ALP rather than K-Neg. Conclusion: Bone Graft Substituted using Nanocrystalline HA-CaSO4 is a good material that can repair and increase callus formation in fracture model rats with bone defects.

W-Cu composites are commonly used as heat-sinks or high-performance switches in power electronics. To enhance their mechanical properties and mutually their usability, grain refinement of the initially coarse-grained microstructure was realized using high–pressure torsion. This leads to different microstructural conditions, exhibiting fine-, ultrafine-grained or nanocrystalline microstructures. Scanning as well as transmission electron microscopy was performed to analyze the respective grain size and microstructures. The hardness and Young’s modulus of the deformed specimens were quantified by nanoindentation testing. Furthermore, X–ray diffraction indicated a decreased grain size and changed lattice spacings upon increasing the deformation ratio. The deformed specimens were tested for their fracture behaviour by continuous stiffness measurements during in-situ microcantilever bending experiments. Here, mean J–integral values of 288 ± 38 J/m2 and 402 ± 89 J/m2 were determined for the 5 and 50 times turned specimens, respectively. The combination of different characterization methods applied on a W–Cu composite allows to identify both, beneficial and unfavourable microstructural components regarding the fracture properties.

The repair of large-volume bone defects (LVBDs) remains a great challenge in the fields of orthopedics and maxillofacial surgery. Most clinically available bone-defect-filling materials lack proper degradability and efficient osteoinductivity. In this study, we synthesized a novel biomimetically-precipitated nanocrystalline calcium phosphate (BpNcCaP) with internally incorporated bone morphogenetic protein-2 (BpNcCaP + BMP-2) with an aim to develop properly degradable and highly osteoinductive granules to repair LVBDs. We first characterized the physicochemical properties of the granules with different incorporation amounts of BMP-2 using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. We evaluated the cytotoxicity and cytocompatibility of BpNcCaP by assessing the viability and adhesion of MC3T3-E1 pre-osteoblasts using PrestoBlue assay, Rhodamine-Phalloidin and DAPI staining, respectively. We further assessed the in-vivo osteoinductive efficacy in a subcutaneous bone induction model in rats. In-vitro characterization data showed that the BpNcCaP + BMP-2 granules were comprised of hexagonal hydroxyapatite with an average crystallite size ranging from 19.7 to 25.1 nm and a grain size at 84.13 ± 28.46 nm. The vickers hardness of BpNcCaP was 32.50 ± 3.58 HV 0.025. BpNcCaP showed no obvious cytotoxicity and was favorable for the adhesion of pre-osteoblasts. BMP-2 incorporation rate could be as high as 65.04 ± 6.01%. In-vivo histomorphometric analysis showed that the volume of new bone induced by BpNcCaP exhibited a BMP-2 amount-dependent increasing manner. The BpNcCaP+50 μg BMP-2 exhibited significantly more degradation and fewer foreign body giant cells in comparison with BpNcCaP. These data suggested a promising application potential of BpNcCaP + BMP-2 in repairing LVBDs.

Different Si/Ti ratios of TiSiCN composite coatings were prepared by using the plasma-enhanced magnetron sputtering (PEMS) technology with a buffer layer of Cr. The influence of Si/Ti ratio on the morphology, composition, microstructure, mechanical and tribological properties of the coatings were investigated by scanning electron microscope, x-ray photoelectron spectroscopy, x-ray diffraction, Raman spectroscopy, nanoindentation and tribometer. The results show the composite coatings mainly consisted of graphite, TiCN, CNx nanocrystals and amorphous Si3N4. TiSiCN composite coating possesses the highest hardness at the Si/Ti ratio of 19/3 due to the increase in amorphous hardening phase, sp3-C hybridized bonding and the grain refinement. Self-lubrication of graphite and amorphous Si3N4 hardening phase significantly reduces the wear rate of the coating. The TiSiCN composite coating with Si/Ti ratio of 3/4 presents the lowest coefficient of friction and wear rate. [ABSTRACT FROM AUTHOR]

Amorphous/nanocrystalline coatings are very useful for high strength, wear and corrosion-resistant applications, and these coatings are usually produced in thermal spray processes because of rapid cooling rates. Here we report, characterization of SHS7170 coatings developed by APS, high-velocity oxy-fuel (HVOF), TWA, and a novel hybrid spray technique. Phase and microstructural analysis of the optimized SHS7170 coatings revealed an amorphous structure with very fine nanocrystals embedded in the HVOF and APS coatings, and crystalline structure with grain size in the range of several nanometers in the TWA and hybrid spray coatings. Mechanical test data obtained from shear punch and impact tests illustrated brittle behavior of the amorphous coatings (APS and HVOF coatings) with lower strength compared to the nanocrystalline coatings (TWA and hybrid coatings). Corrosion tests showed the influence of microstructure and porosity of the coatings on polarization curves obtained. Wear and coefficient of friction data indicated similarities between the HVOF, APS and hybrid coatings, albeit the microstructure of hybrid coatings was noticeably different from the other two. TWA sprayed coatings exhibited higher coefficient friction with higher weight loss compared to the remaining three coatings. Erosion tests indicated higher weight loss for APS and TWA coatings at two different chosen angles and erosion behavior was observed to follow the hardness data of the coatings. [ABSTRACT FROM AUTHOR]

The present research focuses on synthesizing nanocrystalline CoCrNiTiMox (x: molar ratio; x = 1, 1.5 at.%, respectively) high entropy alloy by mechanical alloying of pure metal powders for further application as feedstock in the atmospheric plasma spray process. The paper describes the phase evolution and microstructural transformation of milled powders with respect to the ball milling time and speed. A Retsch PM 100 ball mill with a ball to powder ratio of 10:1 and speeds of 200 and 300 rpm are used to synthesize the feedstock powder for plasma spraying. The ball milled powders were assessed for particle size, phase transformation and surface morphologies at regular intervals of 10, 20, 30, 40 and 50 h to optimize the ball mill process parameters. The particle morphology and chemical homogeneity studies were done by scanning electron microscope along with energy dispersive spectroscopy. The influence of Mo variation in the CoCrNiTiMox high entropy alloy in phase formation and crystal structure is studied using the x-ray diffraction technique. The results reveal that the CoCrNiTiMox high entropy alloy possesses two BCC solid solution phases and the powder milled for 10 h is selected as the feedstock powder for plasma spray due to its morphology and good homogeneity of mixing. [ABSTRACT FROM AUTHOR]

The formation of phases in the Al rich peritectic compositions of Al - Cr system was investigated under mechanical milling (MM) and subsequent annealing. MM led to the formation of nanocrystalline Al (Cr) solid solution and also caused carbon contamination originating from the organic process control agent (PCA). Al11Cr4 and AlCr2 phases were formed on annealing instead of the equilibrium peritectic compounds. Additionally, AlCr2C phase was also detected after annealing of Al-16 to 33Cr whereas Al-13Cr did not produce any intermetallic compound. The generation of the intermetallic phases was attributed to classical theories of nucleation and growth. [ABSTRACT FROM AUTHOR]

Zr-Cu based thin-film metallic glass (TFMG) has good glass-forming ability and the addition of a third element can create a chaotic system capable of inhibiting the nucleation and growth of crystals. This study focused on TFMGs made with Zr, Cu, and Ti in various compositions deposited via high-impulse magnetron sputtering on silicon and 304 stainless-steel substrates. Detailed analysis was performed on the microstructure and surface characteristics of the resulting coatings. Transmission electron microscopy revealed that the multilayer structure changed to a nanocrystalline structure similar to an amorphous coating. The excellent hydrophobicity of Zr-Cu-Ti TFMGs can be attributed to their ultra-smooth surface without any grain boundaries. The excellent antimicrobial effects can be attributed to a hydrophobic surface resisting cell adhesion and the presence of copper ions, which are lethal to microbes. [ABSTRACT FROM AUTHOR]

The synthesis of highly crystalline mesoporous materials is key to realizing high‐performance chemical and biological sensors and optoelectronics. However, minimizing surface oxidation and enhancing the domain size without affecting the porous nanoarchitecture are daunting challenges. Herein, we report a hybrid technique that combines bottom‐up electrochemical growth with top‐down plasma treatment to produce mesoporous semiconductors with large crystalline domain sizes and excellent surface passivation. By passivating unsaturated bonds without incorporating any chemical or physical layers, these films show better stability and enhancement in the optoelectronic properties of mesoporous copper telluride (CuTe) with different pore diameters. These results provide exciting opportunities for the development of long‐term, stable, and high‐performance mesoporous semiconductor materials for future technologies. [ABSTRACT FROM AUTHOR]

CdSe nanocrystallines with different micromorphology were synthesized by inverse microemulsion method. X-ray diffraction and transmission electron microscopy were used to characterize the micromorphology, phase and ingredient compositions of nanocrystallines. The results indicate that nanosphere, necklace-shaped and bamboo-likeCdSe nanocrystals were successfully prepared. The bamboo- like nanotubes have the best crystallization performance. The red shift of the fluorescence peak can be observed clearly, and bamboo-shaped nanotubes have stronger fluorescence emission. Detailed study on the formation of bamboo-like nanotubes was performed. The mechanism is as follows: the difference of the bound water content at the interface and the free water content in the water core leads to the density difference between outer layer and the center. The diffusion of Se2- and Cd2+induces hollow structure of CdSe nanospheres. Due to the small size effect, hollow nanospheres grow into necklace-shaped and bamboo-structure finally. [ABSTRACT FROM AUTHOR]

Post-annealing effects on microstructure and magnetic properties of Nd-Fe-B die-upset magnets were investigated using the commercial melt-spun flakes with a composition of Nd13.6Fe73.6Ga0.6Co6.6B5.6. The die-upset magnets from the melt-spun flakes were subjected to post-annealing at temperatures ranging from 400 °C to 800 °C for 1 h in vacuum and then again annealed at a constant temperature, 600 °C. The coercivity was largely enhanced about 2.4 kOe after the first post-annealing treatment at 600 °C. However, the coercivity decreased at temperatures except for 600 °C and 700 °C. In the case of high temperature, 800 °C, annealing caused the grain growth, resulting coercivity degradation. After the second post-annealing treatment at 600 °C, the coercivity of the magnets post-annealed at low temperatures below 500 °C increased, whereas the coercivity of the magnets post-annealed at above 700 °C decreased. The $\alpha $ and ${N} _{\mathrm {eff}}$ values obtained from the result of temperature dependence of coercivity increased after post-annealing at 600 °C. These results indicate that post-annealing at 600 °C was effective in improving the grain surface structure, but could induce the local stray field in the magnet. [ABSTRACT FROM AUTHOR]

PdCuNiSb alloys were synthesized in IMSETHAC BAS laboratory. The base alloys were foamed with 2, 3 and 4 mass. % ZrH2 in an induction furnace in Ar atmosphere. The microstructure and phase composition of the base Pd- 42Cu28Ni10Sb20 alloys and the foams PdCuNiSb(Zr) were determined by SEM and XRD. The chemical compositions of the structural components were determined and it was proven that zirconium was present mainly in the eutectic and less in the solid solution in the foams. An amorphous phase was found in all PdCuNiSb(Zr) alloys after foaming. The volume part of the amorphous phase increased with the Zr content increase and reached 10 % in the foam with 4 mass. % ZrH2. An unknown phase with a cubic lattice and 7.18Å lattice parameter substituted the amorphous phase of the foams after annealing. The DSC analysis demonstrated, that the increase of zirconium content from 2 to 4 mass. % in PdCuNiSb(Zr) foams lowered the glass-forming temperature and increased the enthalpy of the primary crystallization, respectively the amount of the amorphous part. [ABSTRACT FROM AUTHOR]

Herein, Ni–Co–Cu ternary alloy coating is prepared by electrochemical additive manufacturing. Using potential as a variable parameter, the morphology, organization phase, composition, and performance of the coating are analyzed. The results show that current density, coating structure, and chemical composition varies depending on the potential parameters. As the potential increases, the thickness of the coating increases (5–10 μm), and the content of Co and Cu decreases (Co: 32.5–16.3 wt%. Cu: 27.6–8.7 wt%). The coating has a distinct multilayer structure with a thickness of nanometers per layer. The Ni–Co–Cu coatings prepared herein are all FCC nanocrystalline structures (90–100 nm). In a 3.5 wt% NaCl solution, the corrosion resistance of the coating decreases with the increase of potential parameters. The Ni–Co–Cu coating prepared under the lower potential parameter (−2.5 V) has the smallest corrosion current (9.32 × 10−6 A cm−2) and higher polarization resistance (53 667 Ω cm2). [ABSTRACT FROM AUTHOR]

Nanocrystalline olivine-structured Mg2SiO4 and MgCoSiO4, with an average particle size of 27 nm and 31 nm, respectively, were successfully synthesized from oxide precursors via mechanochemical methods. The two nanocrystalline products were obtained after milling for 360 min and displayed high concentrations of Mg2SiO4 (>94%) and MgCoSiO4 (>95%), together with minor amounts of WC (~3%) contaminant originating as debris abraded off milling balls and chambers. The macroscopic temperature monitoring of the grinding jars during milling trials recorded a peak temperature of 75 °C. A combination of analytical techniques that included XRD, TEM, SAED, and EDS were employed for the characterization of the synthesized products. [ABSTRACT FROM AUTHOR]