Effect of irradiation and pre-ageing temperature on the mechanical properties of Al–Si alloy

Al–1wt.%Si alloy samples in the solid solution state were irradiated with doses of gamma rays up to 1.75 MGy for 2 h in the temperature range from 423 to 553 K. Induced variations in structure, mechanical and electrical properties were traced by suitable techniques. Observed changes in the measured parameters, internal friction Q ^?1, thermal diffusivity D _th, dynamic elastic modulus Y and resistivity, ρ, were explained in terms of the role and mode of interaction of lattice defects in irradiated and thermally treated samples. Composition inhomogeneity and variations in mass distribution in the matrix were also considered. The structure identification of the samples was carried out by using conventional X-ray diffraction techniques and transmission electron microscopy micrographs.     

Effect of Sn and Al additions on the microstructure and mechanical properties of amorphous Ti–Cu–Zr–Ni alloys

Amorphous Ti–Cu–Zr–Ni alloys with minor addition of Sn and Al were prepared by melt spinning technique.The effects of Sn and Al additions on the microstructures and mechanical properties of glassy ribbons were investigated.The amorphous state of ribbons was confirmed by x-ray diffraction and transmission electron microscopy,where those ribbons with Sn addition exhibited a fully amorphous state.The characteristic temperature indicates that Ti_(45)Cu_(35)Zr_(10)Ni_5Sn_5 alloy has a stronger glass-forming ability,as proven by differential scanning calorimetry.Ti_(45)Cu_(35)Zr_(10)Ni_5Al_5 alloy showed a better hardness of 9.23 GPa and elastic modulus of 127.15 GPa and good wear resistance.Ti_(45)Cu_(35)Zr_(10)Ni_5Sn_5 alloy displayed a pop-in event related to discrete plasticity according to nanoindentation.When the temperature is below 560 K,Ti_(45)Cu_(35)Zr_(10)Ni_5Sn_5 alloy mainly exhibits elasticity.When the temperature rises between 717 K and 743 K,it shows a significant increase in elasticity but decrease in viscoelasticity after the ribbon experiences the main relaxation at 717 K.When the temperature is above 743 K,the ribbon shows viscoplasticity.     

The reinforcement ability of ozone-treated CNFs on mechanical properties of C–epoxy composites

Carbon nanofibers (CNFs) are ozone-treated for different time durations (45 and 90 min). Changes in surface characteristics of CNFs due to ozone treatment were studied with BET surface area analyzer and Raman spectroscopy. Raman spectroscopic studies showed that ozone treatment is imparting enhanced degree of disorder for CNFs. Changes in surface functional groups of CNFs due to ozone treatment were estimated using elemental analysis and thermogravimetric analysis. The influence of ozone-treated CNFs on the mechanical properties of laminated (2D) carbon fiber-reinforced epoxy matrix (CFRP) composites has been studied. Results indicate that ozone-treated CNFs can improve the mechanical properties of CFRPs significantly as compared to untreated CNFs due to enhanced interface compatibility between the ozone-treated CNFs to the matrix. Ozone treatment of CNFs proposed in this study has the potential to overcome the limitations of the conventional methods of generating functional groups.     

Effect of Pt on interdiffusion and mechanical properties of the γ and γ′ phases in the Ni–Pt–Al system

The effect of Pt on the growth kinetics of the γ′-[Ni(Pt)]₃Al ordered intermetallic phase and the γ-Ni(Pt, Al) solid solution diffusion rates of the species, hardness and elastic modulus was examined by employing the diffusion couple experimental technique. Experiments were conducted by using the β-Ni(Pt)Al phase and Ni(Pt) alloy couples, each of which had a fixed amount of Pt (5, 10 and 15 at. %) in both the end members so that the Pt content is more or less constant throughout the interdiffusion zone. The results suggest that the growth kinetics of both phases and the average effective interdiffusion coefficients of Ni and Al increase with the increase in Pt content. Nanoindentation studies across the compositional gradients show that the mechanical properties of the intermetallic phase in the superalloy are relatively insensitive to the presence of Pt but are more sensitive to the Ni/Al ratio. In contrast, the marked variation in the hardness of the γ phase were noted, increasing markedly with Al concentration in a given couple and also increasing with increasing Pt content. Possible causes for the observed variations are discussed.     

Effects of Re microalloying on glass formation and mechanical properties of Zr–Cu–Al alloys

The effect of microalloying with rhenium on a metallic glass-forming alloy (Cu₄₆Zr₄₆Al₈)_{100? x} Re _x (x?=?1,?2) was investigated. Re possesses a positive enthalpy of mixing within the Cu–Re terminal system. Splat quenched foils of ≈40?µm in thickness display an amorphous structure. Their crystallisation temperature increases from T _x?=?504 to 513°C with addition of Re at nearly constant glass formation temperature T _g?=?445°C for the amorphous samples. In contrast, injection cast rods consist of B2-CuZr type phase dendrites, minor fractions of a cubic phase CuZrAl, and randomly distributed small particles of a Re-rich phase. This represents a novel concept in microalloying where Re-rich precipitates trigger the B2 phase formation. It leads to a unique combination of mechanical properties for as-cast rods, which display high strength at sizeable plastic deformation up to ε _p?≈?4% and an extended range of work-hardening prior to failure.     

Effect of oxygen partial pressure on the structure and properties of Cu–Al–O thin films

We have studied the electrical and optical properties of Cu–Al–O films deposited on silicon and quartz substrates by using radio frequency (RF) magnetron sputtering method under varied oxygen partial pressure P_O. The results indicate that P_O plays a critical role in the final phase constitution and microstructure of the films, and thus affects the electrical resistivity and optical transmittance significantly. The electrical resistivity increases with the increase of P_O from 2.4 × 10^?4 mbar to 7.5 × 10^?4 mbar and afterwards it decreases with further increasing P_O up to 1.7 × 10^?3 mbar. The optical transmittance in visible region increases with the increase of P_O and obtains the maximum of 65% when P_O is 1.7 × 10^?3 mbar. The corresponding direct band gap is 3.45 eV.     

Effect of annealing temperature on the microstructure and optical–electrical properties of Cu–Al–O thin films

We have successfully prepared Cu–Al–O thin films on silicon (100) and quartz substrates by radio frequency (RF) magnetron sputtering method. The as-deposited Cu–Al–O film is amorphous in nature and post-annealing treatment in argon ambience results in crystallization of the films and the formation of CuAlO₂. The annealing temperature plays an important role in the surface morphology, phase constitution and preferred growth orientation of CuAlO₂ phase, thus affecting the properties of the film. The film annealed at 900 °C is mainly composed of CuAlO₂ phase and shows smooth surface morphology with well-defined grain boundaries, thus exhibiting the optimum optical–electrical properties with electrical resistivity being 79.7 Ω·cm at room temperature and optical transmittance being 80% in visible region. The direct optical band gaps of the films are found in the range of 3.3–3.8 eV depending on the annealing temperature.     

Laser irradiation effects on the surface,structural and mechanical properties of Al–Cu alloy 2024

Laser irradiation effects on surface, structural and mechanical properties of Al–Cu–Mg alloy (Al–Cu alloy 2024) have been investigated. The specimens were irradiated for various fluences ranging from 3.8 to 5.5 J/cm² using an Excimer (KrF) laser (248 nm, 18 ns, 30 Hz) under vacuum environment. The surface and structural modifications of the irradiated targets have been investigated by scanning electron microscope (SEM) and X-ray diffractometer (XRD), respectively. SEM analysis reveals the formation of micro-sized craters along the growth of periodic surface structures (ripples) at their peripheries. The size of the craters initially increases and then decreases by increasing the laser fluence. XRD analysis shows an anomalous trend in the peak intensity and crystallite size of the specimen irradiated for various fluences. A universal tensile testing machine and Vickers microhardness tester were employed in order to investigate the mechanical properties of the irradiated targets. The changes in yield strength, ultimate tensile strength and microhardness were found to be anomalous with increasing laser fluences. The changes in the surface and structural properties of Al–Cu alloy 2024 after laser irradiation have been associated with the changes in mechanical properties.     

Influence of vacuum annealing on structures and mechanical properties of Al–Ti–N films deposited by multi-arc ion plating

The Al–Ti–N films deposited by multi-arc ion plating have been annealed in vacuum within the range of 700–1100 °C. X-ray diffraction results showed that the structure of the films underwent the formation of coherent c-TiN and c-AlN for the annealing temperatures were up to 900 °C. A new phase AlTi_x (x = 0.50, 0.56, 3) was observed after annealing. The X-ray photoelectron spectroscopy results showed the intensity of Ti–Al bonds decreased as annealing temperatures increased, indicating the decomposition of (Al, Ti)N into c-TiN and c-AlN were at the expense of Ti–Al bonds. Differential scanning calorimetry experiments were used to investigate the dynamic behavior of the films during annealing process and the results showed that the N₂ formed as a consequence of the phase transformation process. The release of the N₂ resulted in the peeling of the films from the substrates. The film exhibited a maximum hardness of 39 GPa after 900 °C annealing due to the formation of coherent c-TiN and c-AlN phases. In addition, we also investigated the influence of vacuum annealing on adhesive strength.     

Synthesis,characterization and mechanical properties of nylon–silver composite nanofibers prepared by electrospinning

Silver (Ag) nanoparticles (∼3 nm) were synthesized using silver nitrate as the starting precursor, ethylene glycol as solvent and poly (N-vinylpyrrolidone) (PVP) introduced as a capping agent. These nano-Ag particles were reinforced in nylon matrix by electrospinning of nylon-6/Ag solution in 2,2,2-trifluoroethanol and composite nanofibrous membranes were synthesized. The effects of solution concentration and relative humidity (RH) on the resultant fibrous membranes were studied. Scanning electron microscopy and Transmission electron microscopy was used to study the size and morphology of the fibers. It was observed that concentration and RH could be used to modulate the fiber diameter. Tensile test was used to evaluate the mechanical property of these electrospun composite membranes. The composite membranes showed higher strength (approx. 2–3 times increase in strength) compare to as synthesized nylon fibers.     

Magnetic and mechanical properties of Ni–Mn–Ga/Fe–Ga ferromagnetic shape memory composite

A ferromagnetic shape memory composite of Ni–Mn–Ga and Fe–Ga was fabricated by using spark plasma sintering method. The magnetic and mechanical properties of the composite were investigated. Compared to the Ni–Mn–Ga alloy,the threshold field for magnetic-field-induced strain in the composite is clearly reduced owing to the assistance of internal stress generated from Fe–Ga. Meanwhile, the ductility has been significantly improved in the composite. A fracture strain of 26% and a compressive strength of 1600 MPa were achieved.     

Effect of particle size and alloying with different metals on 57Fe Mössbauer spectra

Iron nanoparticles of various sizes have been synthesized using the chemical route which involves the preparation of iron bipyridine complexes in presence of different capping agents followed by thermal decomposition at 450°C in inert atmosphere. The bimetallic nanoalloys of Fe with Mg and Pd have also been prepared by following the same route. The resulting nanoparticles have been characterized by EDX-RF, XRD, AFM and ⁵⁷Fe Mössbauer spectroscopy. The appearance of quadrupole doublets in the Mössbauer spectra of Fe nanoparticles indicates the absence of magnetic interaction and variation in parameters is due to the varying particle size. The Mössbauer spectrum of Fe–Mg₂ bimetallic nanoalloy shows two doublets indicating the presence of superparamagnetism. The two doublets can be attributed to change in s-electron density of iron resulting from its two neighboring magnesium atoms. Fe–Pd nanoalloy Mössbauer spectrum is characterized by having a superparamagnetic doublet and a ferromagnetic sextet.     

Pressure-dependence of mechanical and thermodynamic properties of Al3Zr in Al–Li alloys from first-principles calculations

The pressure-dependence of mechanical, electronic and thermodynamic properties of metastable (L1₂ type) and stable (D0₂₃ type) Al₃Zr precipitations in Al–Li alloys were investigated by employing the first-principle calculations. The calculated equilibrium parameters are in good agreement with experimental and previous calculation results available. Elastic properties including bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio and universal anisotropic index are determined by Voigt–Reuss–Hill approximation. It is found that for both phases, external pressure can improve the mechanical stability, ductility and plasticity. The electronic structures are determined to reveal the bonding characteristics of both phases. In addition, both phonon method and Gibbs program have been proposed to predict thermodynamic properties of two phases. All of these results can help to have a better understanding of the physical and chemical properties of Al₃Zr precipitations in Al–Li alloy. And can offer theoretical guidance for the weight lighting, energy conservation and emissions reduction in the design of new aluminium alloys.     

Effect of thermal cycling on structure and properties of Ni–Mn–In-based alloys

Technical Physics - The results of investigations of the structure and properties of ternary alloys Ni47–x Mn42 + x In11 (0 ≤ x ≤ 2) after thermal cycling are presented. It has...     

Effect of composition on properties of reactive Al·B·I2 powders prepared by mechanical milling

Metal-based fuels producing halogen-containing combustion products are being developed to enable rapid inactivation of harmful aerosolized spores and bacteria. Ternary reactive materials containing aluminum, boron, and iodine were prepared by mechanical milling with systematically varied Al:B ratio. The aluminum mass fraction varied from 0% to 70%, and most materials included 20 wt% of iodine. Prepared powders were inspected by electron microscopy; particle size distributions were measured using low angle laser light scattering. Stability of materials was studied using thermo-gravimetry and differential scanning calorimetry. As-prepared as well as pre-heated and quenched samples were analyzed using x-ray diffraction. Iodine was released upon heating in several stages. Low-temperature iodine release was relatively small. It overlapped with decomposition of B(OH)₃ releasing water. The most significant amounts of iodine were released when the samples were heated to 400–500 °C, when AlB₂ formed. Both AlB₂ formation and iodine release were further accelerated by melting of aluminum. For the boron-rich samples, in which boron remained after all aluminum was used to form AlB₂, an additional, high-temperature iodine release stage was observed near 900 °C. The results show that both boron and aluminum are capable of stabilizing substantial quantities of iodine in the metal matrix. The iodine is released at temperatures much greater than its boiling point. The mechanism by which iodine is retained in boron and aluminum remains unclear.     

Effect of concentration and particle size on nonlinearity of Au nano-fluid prepared by γ (Co) radiation

Nonlinear properties of Au nano-fluid prepared by γ-radiation method at different concentrations were investigated. Measurements of nonlinear refractive index and nonlinear absorption coefficient were carried out using a single beam Z-scan technique. A green CW laser beam operated at 532 nm was used as excitation source. The Au nano-fluid shows a good third order nonlinear response. The sign of the nonlinear refractive index is found to be negative and the magnitude is in the order of 10⁻⁷ cm²/W. This nonlinear effect increases as the concentration increases from 3.119 × 10⁻⁴ to 2.354 × 10⁻³ M which correspond to particle sizes of 4.0-30.5 nm, respectively. A good linear relationship was obtained between nonlinear refractive index and concentration. However the relationship between nonlinear refractive index and particle size was nonlinear behavior.     

Effect of the amounts of glycidyl methacrylate on the mechanical and dynamic properties of styrene–butadiene–glycidyl methacrylate terpolymer/silica composites

GMA-SBRs with GMA contents in the range of 0.06–0.71 wt.% were synthesized and used to evaluate the properties of the silica composites for fuel-efficient tires. The chemical structures of the GMA-SBRs were analyzed using Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance (¹H NMR), size exclusion chromatography (SEC), and differential scanning calorimetry (DSC). GMA-SBRs can enhance filler–rubber interaction through covalent bond formation between the silica filler and rubber molecules. After compounding, the cure characteristics and mechanical and dynamic properties of the GMA-SBR silica-filled composites were analyzed. The mechanical properties, including the Mooney viscosity, bound rubber, swelling ratio, and moduli, exhibited obvious differences with increasing GMA content. However, the optimum content of GMA in the GMA-SBR, in terms of dynamic properties such as the Payne effect which represents the change in dynamic modulus against the strain to determine the extent of filler flocculation and tan δ at 60 °C representing tire rolling resistance, was ~0.6 wt.%. These results are due to improved silica dispersion, resulting from increased covalent bond formation between GMA-SBR and the silica surface. This approach assists in the determination of functional group contents in functionalized emulsion styrene–butadiene rubber for fuel-efficient tires, leading to a decrease in vehicular greenhouse gas emission.     

Effect of lead on microstructure and some physical properties of Sn–Zn–Cd alloy

The effect of lead on the structure, electrical resistivity, internal friction, elastic modulus and thermal properties of Sn₈₁Zn₉Cd₁₀ ternary alloys have been investigated using different experimental techniques with their analysis. In addition, properties of this alloy were compared with other Sn–Zn or Sn–Zn–Cd alloys and commercial solder alloys. It has a higher electrical resistivity, internal friction and lower elastic modulus when compared with Sn–Zn or Sn–Zn alloys with other additions such as Cd, Bi or In. The Sn₆₁Zn₉Cd₁₀Pb₂₀ alloy has a lower melting point, electrical resistivity and internal friction when compared with the commercial Pb–Sn solder alloy, but it has a similar elastic modulus.     

Effect of annealing temperature on optical and electrochemical properties of chitosan–ZnO nanostructure

Chitosan–ZnO nanostructures were prepared by chemical precipitation method using different concentration of zinc chloride and sodium hydroxide solutions. Nanorod-shaped grains with hexagonal structure for samples annealed at 300 °C and porous structure with amorphous morphology for samples annealed at 600 °C were revealed in SEM analysis. X-ray diffraction patterns confirmed the hexagonal phase ZnO with crystallite size found to be in the range of ~24.15–34.83 nm. Blue shift of UV–Vis absorption shows formation of nanocrystals/nanorods of ZnO with marginal increase in band gap. Photoluminescence spectra show that blue–green emission band at 380–580 nm. The chitosan–ZnO nanostructures used on surface of a glassy carbon electrode gives the oxidation peak potential at ~0.6 V. The electrical conductivity of chitosan–ZnO composites were observed at 2.1?×?10^?5 to 2.85?×?10^?5?S/m. The nanorods with high surface area and nontoxicity nature of chitosan–ZnO nanostructures observed in samples annealed at 300 °C were suitable as a potential material for biosensing.