Optical properties of Si nanowire (SiNW) arrays prepared on p-doped Si(111) and Si(100) substrates were studied. SiNWs were synthesized by self-assembly electroless metal deposition nanoelectrochemistry in an ionic silver HF solution through selective etching. Total reflectance (Rt) and total diffuse reflectance (Rdt) of SiNWs change drastically in comparison to polished Si. To understand these changes, diffuse reflectance (Rd) with polarized incident light was studied. For samples prepared on Si(111), the wave length integrated Rd (wIRd) shows maxima at certain angles of incidence θ, regardless of the incident light polarization. For samples prepared on Si(100), wIRd increases with θ and depends on incident light polarization. Also, Rd spectra show structures due to interference effects. Therefore, SiNWs prepared on Si(100) can be considered as thin films whose refractive index depends on light polarization. Moreover, Rdt of SiNWs prepared on Si(111) can be modeled as an ensemble of diffuse reflectors.

We demonstrate in this paper the shape-controlled synthesis of α-Fe2O3 rhombohedra anchored graphene nanocomposites through a simple hydrothermal strategy by adopting inorganic species in the synthesis system. TEM investigations reveal that the rhombohedra with an average diameter of 80 nm is formed through oriented attachment of primary nanocrystals assisted by Ostwald ripening, and CH3COONa inorganic surfactant played an important role in control over the final morphology of the products. As high-performance anodes for lithium-ion batteries, the obtained Fe2O3 rhombohedra/graphene composite exhibits the first reversible capacity of 905.3 mAh g−1, and high capacity retention of 85.7% after 50 cycles. These values are much higher than those of bare Fe2O3 and Fe2O3 particle/graphene composites, indicating its excellent electrochemical stability. These results give us a guideline for the study of the morphology-dependent properties of functional oxide materials as well as further applications for magnetic materials, lithium-ion batteries, and gas sensors.

Polymer precursors for Si(N)OC ceramics have been synthesized by hydrosilylation reaction of polyhydridomethylsiloxane (PHMS) with three different nitrogen containing compounds. The results obtained by combining characterization techniques such as FTIR, 13C- and 29Si-NMR confirm the occurrence of the cross-linking reaction between Si–H and vinyl groups. The structural characterization of the corresponding ceramic phase shows that the type of N-containing compounds strongly influences the pyrolytic transformation as well as the crystallization behavior of the final ceramics. Elemental analysis clearly indicates that N is present in the Si(N)OC matrix and the degree of N retention after pyrolysis is related to the type of N-containing starting compound. XPS data show that N–C bonds are present in the Si(N)OC ceramic samples even if only N–Si bonds are present in the starting N-containing precursors. However, if nitrogen atoms form bonds with sp2 carbon atoms in the preceramic polymer then a larger fraction of C–N bonds is retained in the final Si(N)OC ceramic.

0.7(0.1BiYbO3-0.9PbTiO3)-0.3 Pb(Mg1/3Nb2/3)O3 (0.7BYPT-0.3PMN) ternary piezoelectric ceramics were prepared by a columbite precursor method. The effects of sintering temperature on the crystalline phase, microstructure, and electrical properties of the ceramics were systematically investigated. There were two phases coexisting in the 0.7BYPT-0.3PMN ceramics sintered at 1100–1250 °C, one is the perovskite host phase with tetragonal symmetry and the other is Yb2Ti2O7 impurity phase. It was observed that, with increasing sintering temperature, the piezoelectric constant d33, dielectric constant εr, planar electromechanical coupling coefficient kp, and Curie temperature TC increased initially and then decreased. An apparent structure distortion could also be observed in samples synthesized at high sintering temperature due to the severe volatilization of Pb and Bi. The optimum performances of the material were obtained for samples sintered at 1150 °C with d33 = 100 pC/N, εr = 494, kp = 25.4%, and TC = 380 °C, respectively. It can be ascribed to the combined effect of a higher density, structural homogeneity with decreased tetragonality as well as a small amount of pyrochlore phase.

Copper microcantilevers were produced by focused ion beam milling and tested in situ using a scanning electron microscope. To provide different interfaces for piling up dislocations, cantilevers were fabricated to be single crystalline, bicrystalline, or single crystalline with a slit in the region of the neutral axis. The aim of the experiment was to study the influence of dislocation pile-ups on (i) strength and (ii) Bauschinger effects in micrometer-sized, focused ion beam milled bending cantilevers. The samples were loaded monotonically for several times under displacement control. Even though the cantilevers exhibited the same nominal strain gradient the strength varied by 34% within the three cantilever geometries. The Bauschinger effect can be promoted and prohibited by the insertion of different interfaces.

Deformation mechanics in equal channel angular pressing (ECAP) was studied in situ using digital image correlation (DIC) and infra-red (IR) thermography. In a prototypical experiment in an optical and IR transparent die, the deformation of commercially pure lead (Pb) is observed using high-speed optical and IR cameras. From the resulting time-sequence images of metal-flow in the deformation zone, DIC is used to characterize the zone of severe plastic deformation (SPD) as a function of the scale of deformation (sample dimensions), deformation speed, and die geometry. The temperature rise in the deformation zone was characterized using IR thermography and the results were compared against theoretical estimates. These observations provide direct insights into the mechanics of SPD in ECAP, which can offer strategies for microstructure control, process optimization, and miniaturization of ECAP.

The influence of substitution of Fe by Ni or Co on the glass forming ability (GFA) and soft magnetic properties of the Fe71−xNb6B23Nix (x = 1–5) and (Fe1−x−yNixCoy)71Nb6B23 (x = 0.1–0.2, y = 0.1–0.2) amorphous ribbons was systematically studied. The Ni or Co substitution for Fe enhances the GFA and decreases the thermal stability for Fe–Nb–B–Ni and (Fe, Ni, Co)–Nb–B alloy systems. The alloys with Ni and Co substitution have lower glass transition temperature and wider supercooled liquid region than that with Ni substitution. The (Fe0.7Ni0.1Co0.2)71Nb6B23 alloys achieved the maximum supercooled liquid region of 78 K. The saturation magnetization decreased and the coercivity increased with increasing Ni or Co content. The (Fe0.8Ni0.1Co0.1)71Nb6B23 amorphous ribbons exhibited the best soft magnetic properties with high saturation and low coercivity. The findings of Fe-based multicomponent alloys with large GFA, low cost, and good magnetic properties are encouraging to develop new soft magnetic materials.

Cast-iron (CI) based bulk amorphous alloy with compositions of Fe75.5−xC6.0Si3.3B5.5P8.7Cu1.0Alx (x = 0, 1 at.%) was synthesized by Cu mold casting. As indicated by increased critical diameters (dmax) for the amorphization, the substitution of Al enhanced the glass-forming ability of the alloy. However, the onset temperature of crystallization (Tx) and the range of supercooled liquid region (ΔTx) of the alloy decreased upon Al addition from 500 °C and 28 °C to 475 °C and 25 °C, respectively. It was revealed that the decreased thermal stability of the amorphous phase is related to the enhanced crystallization tendency to form primary α-Fe phase. Upon the nanocrystallization of primary α-Fe phase the Al-added alloy shows enlarged Ms of 176 emu g−1, still keeping a reasonable small Hc value of 0.086 Oe. The present study revealed that the minor Al addition enhances not only the glass-forming ability, but also the nanocrystallization behavior of the CI based bulk amorphous alloy.

In this study, semi-solid slurry of AZ91–2 wt% Ca (AZ91–2Ca) alloy was prepared by gas bubbling and shaped by rheo-squeeze casting process. The results indicate that fine semi-solid slurry of AZ91–2Ca alloy could be obtained by gas bubbling within 30 s, with primary α-Mg particles having an average diameter less than 50 μm and average shape factor higher than 0.7. With the decrease of pouring temperature from 599 to 590 °C, both tensile strength and elongation of rheo-squeeze casting AZ91–2Ca alloy first increased and then decreased. The rheo-squeeze casting AZ91–2Ca alloy sample prepared at pouring temperature of 596 °C exhibited the peak tensile strength and elongation. Compared with conventional squeeze casting, the improvement in mechanical properties of rheo-squeeze casting AZ91–2Ca alloy was mainly attributed to the grain refinement strengthening, including the refinement and spheroidization of primary α-Mg particles and the refinement in the residual melt.

High performance die castings are urgently expected to be used as structural components subjected to dynamic loading. Therefore, tensile properties, fatigue, and corrosion-fatigue behavior of automotive die cast AlMg5Si2Mn alloy are studied in the current work. The results indicate that the tensile strength and yield strength of the as-cast specimens are obviously lower than those of the age-treated specimens, while the elongation decreases with increasing aging time. Neutral corrosive environment (3.5% NaCl solution) dramatically decreases the fatigue limits from 75 to 50 MPa. Fatigue lives of the directly corroded and precorroded specimens are close to each other. The values of material constants m and C are in the range of 5.756–5.874 and 2.421 × 10−10 to 4.285 × 10−9, respectively. Obscure fatigue striations and featureless facets are observed in crack propagation regions. Anodic dissolution is dominantly responsible for the premature crack initiation and stress corrosion cracking leading to the formation of fractured α-Al matrix.

The carburizing behaviors and mechanisms for Cr35Ni45Nb alloy subjected to different service conditions were studied in a high-temperature vacuum environment. Generally, the carburizing process of an alloy is always accompanied by diffusional heterogeneous reactions regardless of the service condition of the alloy. For a carburized original tube, there is a layered structure at the inner wall of the tube, which is comprised of a M7C3 zone, a M7C3–M23C6 mixed zone, and a M23C6 zone with different morphologies. However, for a 6-year tube (short for a tube serviced for 6 years), the composite oxide layers formed previously act as effective barriers to carbon infiltration. Moreover, the Cr2O3 scale tended to be carbonized to form carbide scale to spall from the surface in a reducing environment, while the SiO2 kept stable all along. Once the oxide layers were removed or carbonized enough, inconceivable internal carburization occurred widely.

The effect of erosion speed on the interaction between erosion and corrosion of the Fe–3.5 wt% B alloy in a flowing zinc bath has been investigated using a rotating-disk technique. The total erosion–corrosion rate increases rapidly, whereas the pure erosion rate tends to increase linearly with an increase in erosion speed and with low damage. The increase in total erosion–corrosion rate is strongly dependent on erosion–corrosion interaction. During the erosion–corrosion process, the severe corrosion reaction roughens the surface by forming a loose corrosion layer and cracks in the anticaustic Fe2B skeleton, which eventually facilitates erosion. The micromechanical scouring effect of liquid zinc worsens corrosion by accelerating the removal of corrosion products and causing spallation of anticaustic Fe2B. An increase in erosion speed intensifies the micromechanical scouring effect of flowing zinc significantly. A strong erosion–corrosion interaction occurs at high erosion speed, which leads to a greater material loss rate.

Poly(L-lactide)/poly(para-dioxanone) (PLLA/PPDO) (85/15 w/w) blends with 0, 1, 3, and 5 wt% poly(para-dioxanone-co-L-lactide) (PDOLLA) as a compatibilizer were prepared by solution coprecipitation. The in vitro hydrolytic degradation (HD) of blend bars with different contents of PDOLLA was studied by immersing the bars in a phosphate buffer solution (PBS) at pH 7.49. To estimate the degradation of blend bars, the weight loss, water absorption, thermal properties, surface morphology, and mechanical properties of blend bars, as well as the pH value changes of the PBS, were studied for 8 wk of HD. By adding 1 and 3 wt% PDOLLA, the weight loss of PLLA/PPDO (85/15 w/w) blends increased from 6.4 to 6.8 and 7.4% after 8 wk of HD, 6.2 and 15.6% increment, respectively, while, the average tensile strength of PLLA/PPDO (85/15 w/w) blends for 2–8 wk of HD increased from 25.8 to 29.0 MPa and 31.0 MPa, 12.4 and 20.2% increment, respectively. Considering their good mechanical properties and HD rate, the PLLA/PPDO (85/15 w/w) blends with 1 and 3 wt% PDOLLA are potential to be used as a medical implant material.

A previously synthesized hyperbranched poly(butylene adipate) (HPBA) polymer was compared with a commercial dendritic polyol (HPOH) as a toughening agent for a commercial one-part epoxy resin. Both modifiers were added in weight percentages of 1, 3, 5, and 10%. The modified epoxies were characterized using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), melt rheological tests, and linear elastic fracture mechanics. Blend morphology and matrix–modifier interactions were evaluated using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis, respectively. The toughness-improvement effect was achieved without substantial impairment of thermomechanical properties or degradation of the thermal stability of the epoxy resin. A meaningful decrease in viscosity was achieved with both modifiers, contributing to an easier infusion processability. No evidence of new chemical linking was found although phase separation was observed by SEM, leading to the conclusion that only interfacial linkage occurs between modifiers and epoxy chains. SEM analysis also clearly shows the fracture mode changing from brittle to ductile by addition of modifiers, which was more evident for blends of HPBA.