Search Results (109)

Titanium carbonitride (TiCN) has emerged as a significant material, bridging the gap between traditional binary carbides and nitrides to offer a comprehensive combination of superior mechanical strength, exceptional wear resistance, and excellent chemical stability. This review comprehensively surveys the research progress in TiCN materials, tracing their evolution from coating technologies to the forefront of nanoparticle synthesis and application. We begin by examining conventional physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques for producing TiCN coatings, highlighting their roles in extending the service life of cutting tools, forming tools, and components subjected to abrasive and corrosive environments. The discussion then shifts to the synthesis of TiCN nanoparticles, covering advanced methods such as laser ablation, solvothermal processes, and precursor pyrolysis, with a critical analysis of their advantages and limitations in controlling particle size, morphology, and stoichiometry. The enhancement in the nanoscale formulation of TiCN on mechanical properties including hardness, fracture toughness, and load-bearing capacity is through grain refinement and nanocomposite strengthening mechanisms. Furthermore, the review delves into the corrosion protection mechanisms imparted by TiCN, whether as a dense coating/film or as a reinforcing nanophase in composite matrices. Finally, we identify current challenges in scalable synthesis and phase stability, and propose future directions, such as the development of multi-functional TiCN-based nanocomposites and hybrid coating architectures for next-generation applications in extreme environments. This work aims to provide a structured reference that connects fundamental material properties with applied technological advancements across the micro- to nanoscale. Full article

This work investigates the structural evolution and electrocatalytic activity of the amorphous metal alloy Al₈₇Y₄Gd₁Ni₄Fe₄ during short-term annealing and its effect on the kinetics of the hydrogen evolution reaction (HER) in 1 M KOH. It is shown that a 5 min heat treatment at 647 ± 2 K initiates controlled nanocrystallisation with the formation of AlFe₂Ni, GdFe₂ and Al(X) (X = Gd, Ni, Y, Fe) phases, which are uniformly dispersed in the amorphous matrix. According to XRD, DSC and HRTEM data, it was established that the formation of intermetallic nanodomains leads to a decrease in charge transfer energy barriers and the appearance of additional active centres of H* adsorption. Electrochemical studies have shown an increase in cathode current density, an increase in i₀ by 2–3 orders of magnitude, and a decrease in R_ct after annealing, confirming the improvement in HER kinetics. Potentiostatic tests showed an increase in the volumetric hydrogen evolution rate from 35.1 to 106.0 mL/(g·min) during the first immersion and up to 217.9 mL/(g·min) during reuse. SEM/EDS analysis revealed surface reconstruction and Ni enrichment after HER, which contributes to the acceleration of the H* recombination stage. The synergy of the amorphous matrix and nanophases ensures high electrocatalytic activity and stability of the system, making annealed AMA a promising low-cost catalyst for alkaline hydrogen evolution. Full article

Fe-based amorphous microwires were studied to examine the effect of partial surface nanocrystallization on their magnetic and electrical properties. Controlled annealing was used to induce nanocrystallization within the surface layer of the metallic core. The giant magnetoimpedance (GMI) was found to increase up to 150% compared to the as-cast microwires, which correlates with variations in the electromagnetic skin depth. Magnetic force microscopy (MFM) revealed a pronounced transformation of the magnetic domain structure: inclined and zigzag domains evolved into a ring domain configuration with radially oriented magnetization. This transformation of the domain structure occurred within the same magnetic field range where the maximum impedance response was observed. These results show a strong coupling between surface nanostructuring, domain configuration, and magnetoimpedance behavior, providing insights for optimizing Fe-based microwires for use in high-sensitivity magnetic and mechanical sensors. Full article

To address surface defects and enhance the wear resistance of 316L stainless steel parts fabricated by Selective Laser Melting (SLM), this study applied shot peening (SP) surface treatment to the SLM-processed samples. Ball-on-disk tribological tests were systematically conducted under water-lubricated conditions to investigate the evolution of surface morphology, microstructure, microhardness, and tribological performance before and after SP. The results indicate that SP induced severe plastic deformation in the surface layer, effectively refining the coarse columnar crystals and melt pool structures characteristic of SLM, and forming a crystalline hardened layer with a depth of 70–80 μm. Consequently, the surface microhardness increased by 21.97% compared to the un-peened samples. Under loads of 20 N and 30 N, the coefficient of friction (COF) of the SP-treated samples decreased by 16.36% and 12.4%, while the wear rate was reduced by 17.09% and 14.9%, respectively. In this load range, the samples primarily exhibited uniform plowing and localized adhesive wear, demonstrating significantly improved resistance to plastic deformation and crack initiation. However, when the load increased to 40 N, intense stress and thermal effects diminished the strengthening benefits of SP, resulting in no significant difference in tribological performance between the SP-treated and untreated samples. At this stage, the dominant wear mechanism transitioned to severe plastic deformation, extensive delamination, and thermally induced adhesion. Full article

Surface nanocrystallization is a critical approach for improving mechanical and functional properties of materials. Beyond conventional mechanical routes, chemical loading presents a promising pathway for nanocrystallization via interstitial-driven phase transformation. However, the characteristics and mechanisms underlying chemical load-induced nanostructuring remain insufficiently elucidated. This work investigates the surface nanocrystallization of 17-4 PH martensitic stainless steel during low-temperature plasma nitriding at 350 °C. Microstructural characterization combining XRD, EPMA, and TEM revealed a nitrogen-saturated layer with a maximum hardness of 13.5 GPa. The modified layer consists of nanoscale domains formed via a diffusionless martensite-to-austenite transformation, as evidenced by broadened FCC peaks, dark-field images, and the absence of elemental partitioning in EDX maps. This process is driven by the cyclic accumulation of chemical and elastic-strain energy at the advancing nitrogen diffusion front, triggering a self-sustaining, periodic transformation. This study introduces a chemical-driven nanocrystallization mechanism for novel design of surface-nanostructured steels via controlled thermochemical processing. Full article

In this study, amorphous Fe₆₀Nb₃B₁₇Si₆Cr₆Ni₄Mo₄ coatings were prepared using the high-velocity air fuel method. The microstructure, wear resistance, and corrosion resistance of the Fe₆₀Nb₃B₁₇Si₆Cr₆Ni₄Mo₄ coatings were examined for various levels of nanocrystallization. In contrast to the as-sprayed coating, the samples that were heat-treated formed partial α-Fe and crystalline Cr₂O₃. The generated nanocrystals exerted a dispersion-strengthening effect on the coatings, leading to enhanced hardness and fracture toughness. When the annealing temperature was below the initial crystallization temperature, the wear resistance improved by approximately 1.65 times, the wear rate decreased to half of that in the as-sprayed state, and the depth of the wear scar reduced. However, the resistance of the coatings to corrosion deteriorated as the degree of crystallization increased. X-ray photoelectron spectroscopy analysis revealed that heat treatment modified the composition of the passive film, thereby influencing its corrosion resistance. These results provide crucial insights into the application of Fe-based amorphous coatings in wear- and corrosion-resistant environments. Full article

This study systematically investigates the surface nanocrystallization of 35CrMo steel induced by Ultrasonic Surface Rolling Processing (USRP). It reveals the formation of a gradient nanostructure, where martensite lath fragmentation under high-frequency impacts leads to a surface layer of equiaxed nanocrystals and high-density dislocations. This novel microstructure yields exceptional surface integrity: roughness is minimized to 0.029 μm due to plastic flow, residual stress is transformed into high compressive stress, and surface microhardness is significantly enhanced by 32.3%, primarily governed by grain refinement and dislocation strengthening. Consequently, the treated material exhibits a 28.9% reduction in wear mass loss, which is directly attributed to the combined effects of the strengthened gradient layer’s improved load-bearing capacity and the effective suppression of crack initiation by compressive residual stresses. Our findings not only provide direct microstructural evidence for classic strengthening theories but also offer a practical guide for optimizing the surface performance of high-strength alloy components. Full article

Bismuth telluride (Bi₂Te₃) is a thermoelectric material that exhibits excellent thermoelectric properties primarily because of its low thermal conductivity. The ideal structure of Bi₂Te₃ contains nanocrystals with a high crystal orientation. However, achieving both nanocrystallization and a high crystal orientation is challenging. Furthermore, experimental analyses of thermal transport properties, namely the sound velocity, lattice thermal conductivity, and phonon mean free path (MFP) are limited. In this study, Bi₂Te₃ thin films were deposited using pressure-gradient sputtering (PGS), and their thermal transport properties were determined. These films exhibited a crystallite size of 23.0 nm and an F value of 0.97, indicating a nearly perfect crystal orientation. The average sound velocity of 2046 m/s, in-plane lattice thermal conductivity of 0.66 W/(m·K), and phonon MFP of 0.37 nm were determined using nanoindentation, the 3ω method, and a combination of both of these methods, respectively. The dimensionless figures of merit of the Bi₂Te₃ thin films were 1.3 × 10⁻¹ and 1.0 × 10⁻¹ in the in-plane and cross-plane directions, respectively. The PGS system is useful for the fabrication of high quality thermoelectric materials, and the analysis method that combines the 3ω method and nanoindentation provides a detailed estimation of their thermal transport properties. Full article

In this study, the influence of annealing on the phase evolution and mechanical properties of the Fe₆₂Ni₁₈P₁₃C₇ (at.%) alloy was investigated. Ribbons produced via melt-spinning were annealed at various temperatures, and their structural transformations and hardness were evaluated. The alloy exhibited a narrow supercooled liquid region (ΔT_x ≈ 22 °C), confirming its low glass-forming ability (GFA). Primary crystallization began at approximately 380 °C with the formation of α-(Fe,Ni) and Fe₂NiP, followed by the emergence of γ-(Fe,Ni) phase at higher temperatures. A significant increase in hardness was observed after annealing up to 415 °C, primarily due to nanocrystallization and phosphide precipitation. Further heating resulted in a hardness plateau, followed by a noticeable decline. Additionally, samples were produced via selective laser melting (SLM). The microstructure of the SLM-processed material revealed extensive cracking and the coexistence of phosphorus-rich regions corresponding to Fe₂NiP and iron-rich regions associated with γ-(Fe,Ni). Full article

This study investigates the effects of molybdenum (Mo) additions on the crystallization behavior and soft magnetic properties and of Fe_82-xSi₄B₁₂Nb₁Mo_xCu₁ (x = 0–2) nanocrystalline alloys. Molybdenum enhances glass-forming ability (GFA) and magnetic properties by increasing negative mixing enthalpy ($∆{\mathrm{H}}_{\mathrm{m}\mathrm{i}\mathrm{x}}$), mixing entropy ($∆{\mathrm{S}}_{\mathrm{m}\mathrm{i}\mathrm{x}}$), and atomic size mismatch ($\delta$), which stabilize the amorphous phase. X-ray diffraction (XRD) analysis shows that Mo addition improves amorphous phase stability, further enhancing GFA. The simultaneous addition of Mo and Nb increases mixing entropy, promotes nucleation rates, and creates favorable conditions for optimizing nanocrystallization. Upon annealing, this optimized microstructure demonstrated low coercivity and high permeability. Notably, the Fe₈₀Si₄B₁₂Nb₁Mo₂Cu₁ ribbon, annealed at 470 °C for 10 min, exhibited exceptional soft magnetic properties, with a coercivity of 4.54 A/m, a maximum relative permeability of 48,410, and a saturation magnetization of 175.24 emu/g. High-resolution transmission electron microscopy (TEM) revealed an average crystal size of 18.16 nm. These findings suggest that Fe_82-xSi₄B₁₂Nb₁Mo_xCu₁ (x = 0–2) nanocrystalline alloys are suitable for advanced electromagnetic applications pursuing miniaturization and high efficiency. Full article

Background/Objectives: Cutaneous leishmaniasis (CL) is a vector-borne neglected disease that can cause permanent deformities. Current chemotherapy based on injections with toxic drugs or oral miltefosine poses many drawbacks, urging the need for new oral therapies. Here, we proposed to increase the bioavailability of NAT22, an intralesionally but not orally active antileishmanial chalcone, through nanocrystallization to promote its oral use in CL. Methods/Results: NAT22 nanocrystals were produced using a solvent-free green process of dry and wet milling that reduced NAT22 crystal sizes by around 1500-fold to 257 nm (nanoNAT22). Such reduction in size increased water solubility by 15-fold to 4.3 µg/mL and ensured stability in the absence of stabilizers for at least one month. Of note, nanoNAT22 in aqueous medium was more selective for parasites (SI = 35.2) than NAT22 in 1% DMSO (SI = 7.6). Leishmania amazonensis-infected mice treated with oral nanoNAT22 had lesion sizes and parasite loads similar to those achieved with intralesional Glucantime^®, and significantly smaller than NAT22. Conclusions: Together, these results indicate that nanocrystallization is an effective process to render NAT22 chalcone also orally active against CL. Full article

The interplay between melting viscosity, amorphous forming ability (AFA), nanocrystalline structure, and soft magnetic properties (SMPs) in Fe-based multicomponent alloys remains unclear. This study systematically explores the effects of Sn doping on the viscosity, precursor structure, and nanocrystallization behavior of Fe-Si-B-Nb-Cu-Al-P alloys. Sn doping reduces melting viscosity and induces an abnormal viscosity rise during cooling, lowering the fragility parameter ratio (F) between high- and low-temperature zones, thereby enhancing the AFA of the precursor ribbons. High-temperature heat preservation treatment (HTP) of the melt further reduces the F, improves precursor disorder, and refines nanocrystals, leading to reduced average magnetocrystalline anisotropy and optimized SMPs. The HTP-treated Sn-dopped alloy shows superior SMPs, including low coercivity of 0.4 A/m and high permeability of 32,400 at 5 kHz, making it highly promising for advanced electromagnetic device applications. This work reveals the relationship between viscosity, precursor structure, nanocrystalline structure, and SMPs of Fe-based alloys, which provides an approach for the optimization of SMPs. Full article

A transparent fluoroborosilicate glass ceramic was designed for the controllable precipitation of fluoride nanocrystals and to greatly enhance the photoluminescence of active ions. Through the introduction of B₂O₃ into fluorosilicate glass, the melting temperature was decreased from 1400 to 1050 °C, and the abnormal crystallization in the fabrication process of fluorosilicate glass was avoided. More importantly, the controlled crystallizations of KZnF₃ and KYb₃F₁₀ in fluoroborosilicate glass ceramics enhanced the emission of Mn²⁺ and Mn²⁺–Yb³⁺ dimers by 6.7 and 54 times, respectively. Moreover, the upconversion emission color of glass ceramic could be modulated from yellow to white and blue by adjusting the Yb³⁺ concentration. The well-designed glass ceramic is a novel and significant compound to simultaneously provide efficiently coordinated sites for transition metal and rare earth ions. More importantly, the design strategy opens a new way for engineering high-quality oxy-fluoride glass ceramics with properties of excellent stability, controllable nano-crystallization and high-efficiency photoluminescence. Full article

Owing to their high producibility and resistance to corrosion, austenitic chromium–nickel steels are widely used in the chemical, petroleum, and food industries. However, their significant disadvantage lies in their poor structural performance, which cannot be improved by heat treatment. This significantly limits the usability of these steels in parts of machines that operate under friction loads. Hardening can be achieved by decreasing the size of grains and applying deformation-induced martensitic transformation. Nanostructuring burnishing (NSB) may be one of the technologies suited for producing parts of tribological assemblies with enhanced operating characteristics. Nanostructuring burnishing using a sliding indenter is being developed as a method of industrial surface nanocrystallization through severe plastic deformation used in the mechanical machining of various types of parts. This article investigates the possibility of enhancing the mechanical and tribological properties of nanocrystallized surfaces of austenitic steels, which are formed through nanostructuring burnishing using a tool with a natural diamond spherical indenter and a change in sliding speed from 40 to 280 m/min with one, three, and five passes. Increasing the tool sliding speed makes surface nanostructuring machining of big parts highly effective. This paper aims to establish the influence exerted by the sliding speed and number of indenter passes on the formation of a nanocrystalline structure, as well as on the modification of microhardness and residual stresses, texture, and tribological properties of the surface layer in the nanostructuring burnishing of AISI 304 steel. Transmission microscopy and microdurometry, 3D-profilometry, and tribological tests of surfaces nanocrystallized with the “ball-on-disk” scheme with dry and lubricated friction established the optimal values of speed and number of passes for a spherical indenter in nanostructuring burnishing. Full article

In this study, the surface nano treatment of TA2 titanium alloy was realized by means of surface mechanical wear treatment. The microstructure and electrochemical properties of the nanocrystalline layer were investigated by SEM, TEM, Electrochemical Impedance Spectroscopy, and Potentiodynamic Polarization, while the nucleation mechanism of the passivation film was discussed. The results indicate that the original coarse grains on the sample’s surface are transformed into randomly oriented nanocrystals by surface mechanical attrition treatment (SMAT). The corrosion current density of the surface nanocrystallized TA2 titanium alloy (9.2 nA·cm⁻²) experienced a reduction of two orders of magnitude compared to untreated TA2 titanium alloy (134.5 nA·cm⁻²) in 3.5 wt.% NaCl solution. The SMAT methods accelerates nucleation mechanism transitioning to continuous nucleation. Full article