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Abstract: A new class of Al-base multi-phase ultrafine composites with multi-scale microstructure, which exhibits high strength and large compressive plasticity at ambient temperature, has been developed in the Al–Cu–Si ternary system. The formation of the favorable multi-phase multi-modal structure can be achieved by proper alloy selection and by controlling the solidification process. The developed hierarchical ultrafine composites exhibit high fracture strength of ∼1 GPa and large compressive plasticity up to ∼25%. The large macroscopic plastic strain is attributed to the combination of dislocation-based slip deformation in the ductile phase and extensive shear banding in the intermetallic phase. [ABSTRACT FROM AUTHOR]

Red thermoluminescence in quartz has been generally observed in samples from volcanic deposits or archaeological burnt materials. Red thermoluminescence emission quartz has gained attention as a radiation dosimeter for thermoluminescence dating due to the high-dose saturation level and long-term stability of the thermoluminescence signal. The technique for this application can be improved with an understanding of various trap parameters associated with thermoluminescence glow peaks. The repeated initial rise and computerized glow curve deconvolution methods are used to determine the number of thermoluminescence glow peaks and trap parameters for red thermoluminescence from two types of quartz (Tazawa and Yuda samples) from Japan. For both quartz samples, the glow curves were best described as a superposition of seven glow peaks with activation energies of 0.76-1.95 eV and 0.89-1.91 eV for the Tazawa and Yuda samples, respectively. These results provide useful information for the investigation of the intrinsic characteristics of quartz crystals in the research fields relevant to dating and dosimetry. [ABSTRACT FROM AUTHOR]

Abstract: Systematic microstructural investigations in the Ti100−x Co x alloys with x =5, 7 and 9 reveal that the length-scale and distribution of martensitic ω phase can be effectively modified by the additions of small amounts Co. With increasing Co content, homogeneous distribution of nano-scale martensitic ω phase occurs in β-Ti matrix indicating improvement of structural coherency of the ω phase to the β-Ti matrix. A large plasticity of ∼34% combined with the high strength (∼2.9GPa) of the Ti91Co9 sample can be obtained through the local shear dissipation possibly caused by the structural coherency between ω and β phases. [Copyright &y& Elsevier]

Through the systematic replacement of Co for Cu as a β-Ti phase stabilizer in the γ-TiCu alloy, a wide range of (β + γ) two-phase microstructures can be prepared in the Ti50Cu50-xCox alloys. Enhanced yield strength (>850 MPa) combined with high ductility (>22%) of the Ti50Cu40Co10 alloy is attributed to the formation of micron-scaled β dendrites embedded in the γ matrix. By controlling the volume fraction of the β dendrites, simultaneous increases in strength and ductility can be effectively achieved. [ABSTRACT FROM AUTHOR]

The memory characteristics of a capacitor with polycrystalline gallium arsenide (poly‐GaAs) as a floating gate material have been evaluated, and compared with a capacitor using poly‐silicon (poly‐Si). The poly‐GaAs film with thickness of 100 nm was successfully grown on silicon at 250°C, using an arsenide beam flux, in a molecular beam epitaxy chamber. Based on the optical and electrical evaluation, this film appeared to have obvious poly‐GaAs. Here, the measured the memory window by comparing it to a conventional device with a poly‐Si floating gate, which showed it to have approximately twice the value of the poly‐Si. Based on these results, poly‐GaAs floating material can be considered to be a candidate for a wider memory window in scaled two‐dimensional flash memory. [ABSTRACT FROM AUTHOR]

Abstract: A new micro-combustor configuration for a micro fuel-cell reformer integrated with a micro-evaporator is studied experimentally and computationally. The micro-combustor as a heat source is designed for a 10–15W micro-reformer using the steam reforming method. In order to satisfy the primary requirements for designing a micro-combustor integrated with a micro-evaporator, i.e., stable burning in a small confinement and maximum heat transfer through a wall, the present micro-combustor is a simply cylinder, which is easy to fabricate, but is two-staged (expanding downstream) to control ignition and stable burning. The aspect ratio and wall thickness of the micro-combustor substantially affect ignition and thermal characteristics. For optimized design conditions, a pre-mixed micro-flame is easily ignited in the expanded second-stage combustor, moves into the smaller first-stage combustor, and finally is stabilized therein. The measured and predicted temperature distributions across the micro-combustor walls indicate that heat generated in the micro-combustor is well transferred. Thus, the present micro-combustor configuration can be applied to practical micro-reformers integrated with a micro-evaporator for use with fuel cells. [Copyright &y& Elsevier]

Abstract: Light-scattering measurements, in situ laser-induced fluorescence, and thermophoretic sampling with transmission electron microscopy (TEM) analysis, were performed in laboratory isooctane diffusion flames seeded with 4000 ppm iron pentacarbonyl. These measurements allowed the determination of the evolution of the size, number density, and volume fraction of soot particles through the flame. Comparison to unseeded flame data provided a detailed assessment of the effects of iron addition on soot particle inception, growth, and oxidation processes. Iron was found to produce a minor soot-enhancing effect at early residence times, while subsequent soot particle growth was largely unaffected. It is concluded that primarily elemental iron is incorporated within the soot particles during particle inception and growth. However, iron addition was found to enhance the rate of soot oxidation during the soot burnout regime, yielding a two-thirds reduction in overall soot emissions. In situ spectroscopic measurements probed the transient nature of elemental iron throughout the flame, revealing significant loss of elemental iron, presumably to iron oxides, with increasing flame residence, suggesting catalysis of soot oxidation via iron oxide species. [Copyright &y& Elsevier]

Abstract: An enhancement of plasticity in high strength ultrafine eutectic Fe–Nb composites has been accomplished by introducing heterogeneities in length-scale of the microstructure. Addition of Al acting as a stabilizer for the α-Fe phase in the Fe–Nb composites results in the formation of a larger volume fraction of primary α-Fe phase and an ultrafine eutectic structure with reduced lamellar spacing. As a result, Fe–Nb–Al composites exhibit a good combination of fracture strength and plasticity. Due to the presence of the solution hardened α-Fe phase, the Fe–Nb–Al composites exhibit significantly enhanced work hardening behavior at room temperature. [Copyright &y& Elsevier]

Abstract: An arc-melted Zr73.5Nb9Cu7Ni1Al9.5 alloy consists of dendritic body-centered cubic solid solution and a mixture of ultrafine body-centered tetragonal Zr2Cu-type and hexagonal close-packed MgZn2-type phases in the ultrafine matrix. This composite exhibits two exothermic reactions upon heating to 973K with a heating rate of 40K/min. After the first exothermic reaction nano-scale ω-phase particles have formed in the β-phase dendrites indicating a decomposition of the supersaturated solid solution upon heating. At the early stage during the decomposition of the β-phase the ω-phase is coherent with the parent phase without clear structural differences. However, semicoherency between the β- and the nano-scale ω-phase regions was observed during the growth of the ω-phase. This structural semicoherency causes nano-scale twinning in the β-phase dendrites around the ordered ω-phase in order to release the mismatch energy at the interfaces between the ordered ω- and β-phases. [Copyright &y& Elsevier]

Abstract: A series of glass forming alloys (Ti33Zr33Hf33)100− x − y (Ni50Cu50) x Al y (x =20–70at.% and y =0–30at.%) have been developed by equiatomic substitution of similar elements. Of these alloys (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 was chosen in this study to investigate the structural relaxation and glass transition behavior. The as-quenched (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy was fully amorphous and had a wide supercooled liquid region ΔT = T x(503°C)− T g(433°C)=70°C, where T g and T x are the glass transition and crystallization temperatures, respectively. Low temperature pre-heat treatments of the (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy for 10min at 310°C, 370°C and 390°C caused structural relaxation accompanied by the formation of very fine scale lattice ordering. After these heat treatments, the glass transition became hard to observe in the (Ti33Zr33Hf33)50(Ni50Cu50)40Al10 alloy. Increasing the pre-heat treatment temperatures and holding times caused the glass transition to become more clearly detectable with increasing endothermic heat release. [Copyright &y& Elsevier]

The glass-forming ability of Fe-based metallic glass Fe71.2−x C7.0Si3.3B5.5P8.7Cr2.3Al2.0Mo x (x =0–6.5at.%), which can be produced in large quantities and cost-effectively using hot metal and commercial raw materials, was significantly enhanced by optimizing the Mo content, leading to the formation of a fully amorphous rod of 6mm in diameter with high compressive fracture strength (∼3.3GPa). It is concluded that the enhanced glass-forming ability is attributed to the suppression of the primary α-(Fe, Mo) phase by the optimum amount of Mo substitution for Fe. [Copyright &y& Elsevier]

Abstract: Investigation of the microstructure of a compressed Ti66.1Cu8Ni4.8Sn7.2Nb13.9 nanostructure–dendrite composite reveals that the deformed bcc β-Ti dendrites form a stepped morphology at the interfaces between the individual dendrites and the nanostructured matrix of hcp α-Ti and bct Ti2Cu phases. Furthermore, there is a unique stained contrast during the propagation and the interaction of the shear bands in the dendrites indicating a local structural change near to the apex of the shear bands in the dendrite. In contrast, the shear bands pass through coherent grain boundaries between the hcp α-Ti and the bct Ti2Cu phases of the nanostructured matrix. [Copyright &y& Elsevier]

Abstract: A nano-scale icosahedral phase forms as first crystallization product upon devitrification of multicomponent amorphous (Ti33Zr33Hf33)50(Ni50Cu50)40Al10, (Ti33Zr33Hf33)60(Ni50Cu50)30Al10 and (Ti33Zr33Hf33)65(Ni50Cu50)27.5Al7.5 alloys (numbers indicate at.%). The onset temperatures and the values of the activation energy for the devitrification of the nano-scale icosahedral phase decrease with increasing (Ti33Zr33Hf33) content in these alloys. This indicates that the structural similarity between the amorphous and the icosahedral phases increases with increasing (Ti33Zr33Hf33) content. Furthermore, the devitrified nano-scale icosahedral quasicrystals form in a wide compositional range regardless of the (Ti33Zr33Hf33) content suggesting that the icosahedral phase in these novel multicomponent alloys, developed by equiatomic substitution may have an extensive solid solubility. After further heat treatment the devitrified nano-scale icosahedral phase fully decomposes into MgZn2-type crystals reflecting its metastability. [Copyright &y& Elsevier]

Abstract: Zr73.5Nb9Cu7Ni1Al9.5 (numbers indicate at.%) nanostructure-dendrite composites were fabricated using three different casting techniques: suction casting, centrifugal casting and arc-melting. The microstructure of the suction casting sample consists of micrometer-scale dendrites in a nanostructured matrix. However, some areas in the matrix contain nano-scale crystals together with an amorphous phase revealing an inhomogeneity of the specimen. On the contrary, the microstructures of the centrifugally-cast and the arc-melted samples are overall homogeneous, consisting of micrometer-scale dendrites that are homogeneously distributed in a nanostructured matrix. The dendrites correspond to a body centered cubic (bcc) β-Zr phase, whereas the nanostructured matrix consists of body centered tetragonal (bct) Zr2Cu-type and hexagonal close-packed (hcp) MgZn2-type phases. The comparison of the microstructures of these two alloys reveals that the formation of nano-scale twins and a disordered ω-phase in the β-Zr dendrites only happens in the centrifugally-cast sample. The differences in the phases and the microstructures between the differently prepared samples significantly influence the corresponding mechanical properties of the specimens. [Copyright &y& Elsevier]

Abstract: A Ti67.79Fe28.36Sn3.85 (at.%) alloy has been prepared through arc-melting and solidification at a cooling rate of 40–10K/s. The as-prepared microstructure exhibits a two-phase ultrafine eutectic consisting of FeTi (B2) and β-Ti (A2) phases. The mechanical properties (maximum strength, σ max =1939MPa; strain to fracture, ɛ f =13.5%) are considerably improved if compared with the model Ti70.5Fe29.5 eutectic alloy (σ max =1733MPa, ɛ f =3.4%). The improvement of plastic deformability is assessed in terms of a detailed investigation of the microstructure and fractographic studies. The presence of Sn is believed to boost the ease of slip transfer across the interface between the A2/B2 phases due a higher lattice mismatch between the structures. [Copyright &y& Elsevier]