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X-ray diffraction patterns of melt-spun Fe-Cu-Nb-Si-B (FINEMET-type) alloys reveal that crystallites of Fe₂Si and Fe₃B phases with average sizes of 15(5) and 20(2) nm are present in the surface layer of thickness ≈ 10 Å and these nanocrystallites occupy 5–10% of the total volume. The results of an elaborate analysis of the high-resolution electrical resistivity data taken in a temperature range from 13 K to 300 K and their discussion in the light of existing theories demonstrates that the enhanced electron–electron interaction (EEI), quantum interference (QI) effects, inelastic electron–phonon scattering, coherent electron–magnon (and/or electron-spin fluctuation) scattering are the main mechanisms that govern the temperature dependence of resistivity. Of all the inelastic scattering processes, inelastic electron–phonon scattering is the most effective mechanism to destroy phase coherence of electron wavefunctions. The physical quantities such as diffusion constant, density of states at the Fermi level and the phase-breaking time, determined for the first time for the alloys in question, exhibit a systematic variation with the copper concentration.

We studied the theoretical Curie temperature of a dual-phase nanomagnetic system by Monte Carlo simulation of a modified Heisenberg model on a 3D complex lattice consisting of single- and cluster-spins. We also systematically investigated the experimental Curie temperature of a dual-phase nanomagnetic alloy and performed a direct comparison between theory and experiment. The exchange coupling between two component magnetic phases substantially affects the Curie temperature of the intergranular amorphous region of a dual-phase nanomagnetic system. The depends upon the nanocrystallite size d, the volume fraction V_c and the interspace among crystallites ξ. Large crystallized volume fraction V_c, small grain size d, and thin interphase thickness ξ lead to an obvious enhancement of Curie temperature (ECT) of intergranular amorphous region, whereas the Curie temperature of nanocrystallites decreases slightly. By simulation, we worked out a relationship between the reduced ECT and ξ, as , and it conforms to the experimental result. In addition, we also simulated the demagnetization of a hard–soft nanocomposite system. The exchange coupling between two component phases affects the cooperativity of two-phase magnetizations, the coherent reversal of magnetizations, and coercivity.

Fe-based amorphous alloys are widely used in the magnetic apparatus and generally produced by the single-roller copper-wheel melt spinning method. Spray forming is one of the rapid solidification techniques as the spinning method is, seldom used to fabricate Fe-based amorphous alloys. However in this paper, a Fe-based alloy with the nominal composition of Fe_73.5Cu₁Nb₃Si_13.5B₉ (at.%) alloy was fabricated by spray forming technique with the aim of investigating the formation of amorphous phases and novel microstructures by the high cooling rate involved in this process. The gas/metal mass flow rate used was 0.15, and nitrogen was used as the atomization gas. The resulting deposit and the overspray powder had a median diameter of about 50 μm with a total weight of about 2.2 kg. The microstructure of the deposit was observed by utilizing the X-Ray Diffraction (XRD) and Optical Microscope (OM), as well as Transmission Electron Microscope (TEM), which revealed a heterogeneous varying with the thickness, presenting at center region 15 mm and at border 8 mm with porosities 4 and 9%, respectively. The thicker region showed a fully crystalline microstructure with grain size of about 250nm, whereas the thinner region had a partially amorphous phase with an average grain size of 40nm. The overspray powder was fully crystallized with the grain size of 80nm which was calculated from XRD spectra using the Scherrer formula. The magnetic properties were measured through VSM, giving a poor magnetic saturation value of about 0.3~0.6T. The coercive force was increased significantly.

Cold gas dynamic spraying (CGDS) technique makes use of high-speed gas current to spray diversified metal, alloy and composite materials under room temperature or with a little heated. It is one kind of novel surface engineering technologies, aimed at eliminating such negative influences as oxidation, gasification, melt, crystallization and gas decomposition and so on existing in hot spraying technologies. Due to its peculiar characteristics such as low spraying temperature, non-oxidation, low stress among coating layers, compactification, and high utilization rate of raw materials, as well as effective applications in the domain of fabricating coatings, the CGDS technique has attracted great attention. As it has the advantages aforementioned, especially avoiding the changes of material properties resulted from high spraying temperature, CGDS provides a kind of revolutionary means for fabricating such heat-sensitive materials as amorphous alloys. The paper reviews the current situation and application development of the CGDS technique, and presents our preliminary exploration of fabricating bulk Fe-based amorphous alloy via CGDS together with mechanical milling process.

Formation of icosahedral clusters in Ni_66.7Zr_33.3 alloy during rapid solidification is studied with molecular dynamics simulations. It is found that the growth rate of the smallest icosahedral cluster (Ih13) in Ni_66.7Zr_33.3 alloy reaches its maximum at glass transition temperature region. The Ih13 in Ni_66.7Zr_33.3 alloy contain the retained from the higher temperatures and the new grown, which reach its maximum at about 900K as well as the new grown vertex atoms of Ih13. The ratio of new grown center atoms to the new grown vertex atoms increases with decreasing temperatures, which implies that the new Ih13 form beside original Ih13 and the icosahedral clusters coalesce to the larger ones during solidification. The stabilities of center atoms and vertex atoms of Ih13 increase with decreasing temperatures, and the stability of the center atoms becomes larger than that of vertex atoms blow 900K because of its rapid increase at glass transition temperatures. The results show that the evolutions of atomic arrangement during cooling change abruptly at glass transition region.

Amorphous materials of the Si-(B)-C-N system have recently attracted considerable interest because of its hardness, low density, durability at extremely high temperature and easy to be prepared from precursor compounds by polymer route. The materials show a great potential to be used in the field of the Thermal Protective System (TPS) for the aircrafts, while the microstructure and chemical configuration are still not clearly revealed due to its complicated covalent character for this multi-component amorphous material. This paper focused on the characterization of polymer derived Si-(B)-C-N amorphous ceramic, various method were employed in order to obtain accurate information about the microstructure, chemical composition, bonding mode of components, such as TEM, EPMA, NMR and FT-IR. SiC crystalline was found existing in the amorphous glass, which indicates the preparation process was achieved accompanied by crystallization of SiC from polymer precursor. The microstructure of the researched material was analyzed and relative accurate chemical composition was obtained on the basis of characterization result, furthermore the covalent character of the amorphous material was deduced according to the characterization results obtained.

Annealing study of amorphous bulk and nanoparticle iron at temperatures from 500 K to 1000 K has been carried out using molecular dynamics (MD) simulations. The simulation is performed for models containing 10⁴ particles Fe at both crystalline and amorphous states. We determine changes of the potential energy, pair radial distribution function (PRDF) and distribution of coordination number (DCN) as a function of annealing time. The calculation shows that the aging slightly reduces the potential energy of system. This result evidences that the amorphous sample undergoes different quasi-equilibrated states during annealing. Similar trend is observed for nanoparticles sample. When the samples are annealed at high temperatures we observe the crystallization in both bulk and nanoparticle. In particular, the system undergoes three stages. At first stage the relaxation proceeds slowly so that the energy of system slightly decreases and the samples structure remains amorphous. Within second stage a structural transformation occurs which significantly changes PRDF and DCN for the relatively short time. The energy of the system is dropped considerably and the amorphous structure transforms into the crystalline. Finally, the crystalline sample undergoes the slow relaxation which reduces the energy of system and eliminates structural defects in crystal lattices.

We have studied dynamics in the liquid and amorphous Fe by means of molecular dynamics (MD) simulation. A series of MD models containing 10⁴ particles under periodic boundary conditions are prepared at temperatures from 290 K to 2250 K. It was shown that the second peak of the radial distribution function (RDF) appears to split when the liquid transforms to an amorphous solid. Further, we focus on local density fluctuations (LDF) which happen in simulated samples. We found that LDFs operate as a diffusion vehicle. The diffusion is performed by two types of LDFs. As the temperature decreases, LDFs are strongly correlated so that the fraction of I-type LDFs increases and the spatial distribution of LDFs is heterogeneous. We propose a new model for diffusion in liquid and amorphous solids which gives new insight into the dynamics slowdown below the melting point and diffusion mechanism in amorphous materials.

In this paper, rapid quenching of Ni from crystal to metallic glass (MG) at different external pressures is simulated by molecular dynamics. The pair distribution functions (PDFs), mean-square displacement, glass transition temperature ($T_g$) and elastic property are calculated and compared with each other. The split of the second PDF peak means the liquid’s transition to glass state starts as previously reported for other MGs. And the $R_i/R_1$ ratio rule is found to hold very well in Ni MG and reveals the SPO structural feature in the configurations. Moreover, with high external pressure, $T_g$ values are more approximated by density–temperature and enthalpy–temperature curves. At last, the elastic modulus and mechanics modulus of quenching models produced a monotonous effect with increasing external pressure and temperature.

The mixed spin-1/2 and spin-1 Blume–Capel model is studied with randomly alternated coordination numbers (CN) on the Bethe lattice (BL) by utilizing the exact recursion relations. Two different CNs are randomly distributed on the BL by using the standard–random (SR) approach. It is observed that this model presents first-order phase transitions and tricritical points for variations of CNs 3 and 4, even if these behaviors are not displayed for the regular mixed-spin on the BL. The phase diagrams are mapped by obtaining the phase transition temperatures of the first- and second-order on several planes.

A series of undoped and p-doped a-SiC:H samples have been made in the framework of a research plan for obtaining high quality p-type window layers by "Plasma Enhanced Chemical Vapor Deposition (PECVD)" technique from the mixtures of silane (SiH₄), methane (CH₄) and diborane (B₂H₆) gases. For the optimization of the window layer, the dependence of the electrical (conductivity) and optical (band gap) properties due to altered ratios of methane and diborane gases were investigated. When the diborane gas ratio was changed from Y = 0.06 to Y = 0.24 with an increase of 0.06 steps at a constant of X = 0.948 methane gas ratio, the dark conductivity and optical band gap values changed from ~ 10^-19 (Ω·cm)^-1 to ~ 10^-10 (Ω·cm)^-1 and 2.542 eV to 2.178 eV, respectively, and between these values, the most appropriate layers can be selected.

Soft Co films deposited by a method which we called the "weak magnetron radio frequency (RF) sputtering" have amorphous structures. The amorphous structure varies with the increasing of P_Ar. Static magnetic measurements show that all the films possess high saturation magnetization and a well-defined in-plane uniaxial anisotropy with the easy axis parallel with the applied field. The highest coercivity in the easy axis H_ce and in the hard axis H_ch is only 20 Oe and 9 Oe, respectively. The sputter pressure P_Ar affects essentially the uniaxial anisotropy energy K_u. The GHz permeability of the as-deposited films was measured in the 0.1–5 GHz using the shorted microstrip transmission-line perturbation method. The full-width at half-maximum (FWHM) for the peak in the imaginary part of the permeability at resonance is about 1.3 GHz which is far broader than other FWHM reported.

CoFeB nanotubes were fabricated by electroless plating in magnetic field using anodized aluminum oxide template, and the structural and magnetic properties of CoFeB nanotubes were investigated. It is found that some nano-scale particles form on the wall of nanotubes. Both coercivity ratio and squareness ratio of out-of-plane to in-plane are significantly changed by the applied magnetic field during electroless plating, which indicates that directional ordering in amorphous CoFeB nanotubes are achieved during electroless plating under magnetic field. The results show that the applied field impacts the magnetic anisotropy of amorphous nanotubes. The anisotropy is stronger with the magnitude of applied field increasing.

Corrosion resistance of nanocrystalline Fe_73.5Si_13.5B₉Nb₃Cu₁ alloy was investigated and compared to its amorphous counterpart. Low-temperature crystallization occurred during the annealing of amorphous tapes was used to obtain a nanocrystalline structure. The influence of annealing condition on the structure and corrosion resistance of the alloy in NaCl and H₂SO₄ solutions was investigated. Based on the testing results, it was found that nanocrystalline tapes have higher corrosion resistance than amorphous counterpart and H₂SO₄ can promote the occurrence of corrosion compared with NaCl.

We successfully obtained Ni–B and Ni–B–Ce coatings with and without sonication on low-carbon steel (Q235) through electroless plating with the deposition time of 60min. The surface morphology and elemental composition of the coatings were evaluated by scanning electron microscopy (SEM) and inductively coupled plasma (ICP). The 11$\mu$m thick sonicated Ni–B–Ce (Son-Ni–B–Ce) coating is uniform with the composition of Ni 87.1%, B 6.2% and Ce 6.6%. X-ray diffraction (XRD) measurements implied a typical broaden peak around 44^∘, considered as amorphous structure which was confirmed by selected area electron diffraction pattern (SAED). Atomic force microscopy (AFM) showed a typical circular pit of Ni–B–Ce coating and Son-Ni–B–Ce coating. X-ray photoelectron spectroscopy (XPS) revealed the chemical status of coating components. The mechanical and corrosion resistance properties were determined by Vickers hardness tester, potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy (EIS) in 3.5wt. % NaCl solution. As a result, the Son-Ni–B–Ce coating revealed the optimum hardness (956HV), minimum roughness $R_a$ (92.38nm) and excellent corrosion resistance (3.65$\mu$Acm${}^{-2})$ among all coatings.

Various amorphous SiO_x nanotube structures nucleated by GeO_x nanoparticles were synthesized by thermal evaporation method. The presence of Ge does not only nucleate the growth of the SiO_x nanomaterials, but also dopes them. The nanostructure morphology is affected by the substrate temperature, source temperature and GeO_x vapor density through their effect on the size and lifetime of the nucleation center. In general, low substrate temperature promotes the formation of the nanotube bundle structure with 2–3% atomic ratio of Ge doping, and high temperature produces Ge-free much less bundled nanotubes.

The formation of nanocrystals in Zr-based alloys through three different routes, viz by rapid solidification of alloys, by crystallization of rapidly solidified metallic glasses and by crystallization of bulk metallic glasses has been described. The nanocrystal forming behaviors of rapidly solidified metallic glasses and bulk metallic glasses have been compared and contrasted. The rapidly solidified alloys, which have been examined for this purpose, are Zr₇₆Fe_24-xNi_x (x = 0,4,8,12,16,24) and Zr_69.5Cu₁₂Ni₁₁Al_7.5. In the Zr_69.5Cu₁₂Ni₁₁Al_7.5 alloy, formation of a quasicrystalline phase was observed on crystallization. Bulk glass having the composition Zr₅₂Ti₆Al₁₀Cu₁₈Ni₁₄ has been produced by copper mould casting. This has been crystallized in order to obtain nanocrystalline phases having Zr₂Ni and Zr₂Cu structures. The nanocrystalline and the nanoquasicrystalline microstructures have been examined in considerable detail in order to find out the nature of the various types of interfaces in them. Particularly the nanograin boundaries were examined by high-resolution transmission electron microscope (HREM) and their structure has been compared with that of the grain boundary in large grained material. The change in nature of these interfaces and their number with coarsening of the nanocrystal is also investigated.

The microstructural evolution at different stages of milling of a ternary powder blend of Al₅₀Ti₄₀Si₁₀ composition was monitored by X-ray diffraction, high-resolution transmission electron microscopy, positron annihilation spectroscopy and ²⁷Al nuclear magnetic resonance. Ball-milling leads to alloying, nanocrystallization and partial solid state amorphization, either followed or accompanied by strain-induced nucleation of nanocrystalline intermetallic phases from an amorphous solid solution.

We investigated the compressive strength of PAN-based carbon fibers containing both amorphous and crystalline structures using molecular dynamics simulations. In addition, we investigated the buckling behavior of graphene and graphite crystals under compressive loading. The calculated buckling stresses of those crystals with different aspect ratios agree well with the results by the Euler's buckling theory. We finally found that the compressive strength of the PAN-based carbon fiber with a large amount of amorphous structures was 11 GPa. Moreover, a fracture of the PAN-based carbon fiber begins due to the buckling of carbon layers in crystallites, and propagates with the shear slipping in the crystallites. On the other hand, the compressive strength of the carbon fiber with a small amount of amorphous structures was only 2 GPa. Thus, it was found that the amorphous structure significantly affects the compressive strength of PAN-based carbon fibers.

In this paper, a simple method for synthesizing SiO_x nanowires and nanocoils is presented. Si substrates with an oxide layer were placed in a tube furnace exposed to temperatures ranging from 900°C to 1200°C for a few hours under a mixture of flowing Ar and H₂ gas maintained at ambient pressure. Nanowires were grown from the surface when the furnace temperature was above 1000°C and a high yield could be achieved at 1100°C. SiO_x nanocoils have also been observed and the sample treated at 1000°C had the highest concentration of them. TEM images show that the nanowires and the nanocoils have an amorphous structure and analysis of EDX spectra (obtained in the TEM) shows that x varies from 1.2 to 2.0. The mechanism of growth is discussed.