Search

The cutting performance of a Zr57Cu20Al10Ni8Ti5 (at.%) bulk metallic glass (Zr57 BMG) at low-speed machining was studied, as compared with a Zr48Cu47.5Co0.5Al4 (at.%) bulk metallic glass composite (Zr48 BMGC), commercial industrial pure zirconium (Zr702), titanium alloy (TC4) and 45 steel. The effect of cutting speed, cutting depth, and feed rate on the cutting forces and surface characteristics was examined. Despite with high hardness and strength, Zr57 BMG demonstrated smaller cutting force (Fz) than Zr48 BMGC and Zr702 during machining, resulting from thermal softening. The morphology, roughness, and crystallization on machined surfaces were also investigated. The findings show that Zr57 BMG exhibited excellent machinability at low-speed cutting with excellent surface roughness and no crystallization on machined surface. Scale-like patterns on the machined surface were observed, due to the plastic flow of Zr57 BMG. And it can be effectively suppressed by reducing cutting speed and depth or increasing feed rate. Both spiral and C-shaped chips were formed during the machining of Zr57 BMG, and the proportion of C-shaped chips gradually decreased with the increase of cutting depth and feed rate. A large number of shear bands were found on the back surface of chips, and the C-shaped chips were formed by catastrophic fracture of shear banding during the expansion of spiral chips. Within each shear layer of C-shaped chips, secondary shear bands were observed, which was mainly due to shear localization and catastrophic fracture. Based on orthogonal experiments, the cutting parameters for Zr57 BMG were further optimized and the surface roughness (Ra) was reduced to 0.24 μm, which is comparable to the results obtained by precision machining.

Magnesium alloys, a novel functional material for the fabrication of fracturing tools, are being paid more and more attentions recently due to their relatively high mechanical properties and fast dissolubility ability after fracturing. In this study, the novel extruded Mg–10Gd–3Y–0.3Zr–xNi alloys will be reported and their microstructure, mechanical and corrosion behaviors will be also studied. The results show that Ni contents influence phase precipitation behaviors. With adding 0.2 wt% Ni, a large amount of Zr7Ni10 phases will be precipitated insides α-Mg matrix, directly leading to degradation of strength and large corrosion rate. With further increasing Ni contents, the precipitation phases can be changed from Mg5RE to 18R-LPSO structure, resulting in higher mechanical properties and faster corrosion rate. Moreover, adding Ni element also change the texture orientation by influencing the precipitation behavior of the alloys. The alloys invented in this paper have attained the highest compressive and tensile properties among all the reported dissoluble magnesium alloys. This work is beneficial in understanding the role of Ni in the magnesium alloys and provides more materials alternatives for the fabrication of dissoluble fracturing tools.

We report on a study of the effect of Zn contents on the intragranular and grain boundary precipitation and corrosion behavior of Al-Mg-Si-Cu-Zn alloys. Our results show that with increasing Zn content, peak hardness and intragranular precipitation kinetics of the alloys are enhanced, whereas grain boundary precipitation is negatively affected. The complex interactions that occur between intragranular and grain boundary precipitation lead to differences in intergranular corrosion susceptibility for different aging conditions. Our results provide fundamental insight into the intergranular corrosion response in aged Al-Mg-Si-Cu alloys, as a function of Zn contents.

The distribution and composition of solute-rich features in peak aged Al-Mg-Si-Cu-(Zn) alloys was investigated via three-dimensional atom probe (3DAP) analysis. Our results show that a heterogeneous microstructure can be readily attained via Zn additions with concomitant improvement in the strength, elongation and strain hardening of peak aged alloy. Moreover, Zn partitioning into solute-rich features with a higher Mg/Si ratio (2.46–2.81) and higher number density were observed in the Zn-containing alloy and attributed to strong interactions among Mg, Si, Cu and Zn atoms. The formation of heterogeneous microstructure in the Zn-containing alloy was rationalized due to an increased tendency for clustering.

In this work, the relationship between the accumulation and release of elastic energy during the flow serrations of a bulk metallic glass (BMG) was investigated by use of 10 groups of specimens under varying mixed-mode (I/II) loading conditions. The findings have shown that both the elastic energy accumulation rates and load drops have significant variations, and the load drop data are more scattered than elastic energy accumulation rates. The large variations of load drops are intrinsic for BMGs, while the variations of elastic energy accumulation rates can be reduced to improve/control the plastic deformation of BMGs. Moreover, smaller elastic energy accumulation rates can result in smaller load drops, resulting from the formation of more shear-band intersections. The present work is of significance for understanding the underlying mechanisms of flow serrations of BMGs. It also suggests that more attention could be paid into the elastic energy accumulation process in order to uncover the plastic deformation mechanisms of BMGs.

The formation of bimodal grain size distribution in Al-Mg-Si-Cu alloy and its effect on the formability have been studied by microstructure and property characterization, and modelling. The results reveal that, an attractive way to develop the bimodal microstructure can be greatly used to improve the formability of Al-Mg-Si-Cu alloys, in which the texture can be also weakened. Mechanical properties tests revealed a great improvement in both the formability and anisotropy, i.e. r ¯ = 0.623, Δr = 0.012, can be obtained in the alloy with the bimodal microstructure of coarse and fine grains, which makes this alloy much promising in automotive application. Additionally, according to the microstructure evolution and fracture morphology, both the forming mechanism of bimodal microstructure and deformation mechanism of the Al-Mg-Si-Cu alloys were put forward in this paper.

For characterizing the origins of threshold stress and the evolution of deformation mechanisms in hot working region, the hyperbolic-sine constitutive analyses were conducted to determine the threshold stress σ0, the true stress exponent nt and the true activation energy Qt in AA7050 Al alloys. The origins of σ0 could be related to the four bypassing mechanisms of dislocations overcoming an obstacle. The origins of σ0 are the local climb at 603–633 K, and it may change from the local climb to the detach stress with increasing strains at 663–693 K. The nt and Qt after Young's modulus and threshold stress correction can be associated with the specific deformation mechanism. The deformation mechanisms at peak strains may change from the climb-controlled dislocation creep (lattice diffusion) at 603 K to the Zn diffusion controlled solute drag creep which is controlled by (sub)grain boundary diffusion at 693 K. The nt and Qt decrease with increasing strains may be attributed to the grain boundary self-diffusion accelerated by the fluxes of vacancies for lower temperatures (603–663 K) and the atom diffusion controlled solute drag creep accelerated by the vacancies, (sub)grain boundaries, and the motion of high angle grain boundaries for higher temperatures (663–693 K), respectively. Keywords: True activation energy, Aluminum alloy, Constitutive model, Creep, Threshold stress

Based on the heat dissipation requirement of high heat flux for electronic chips, this paper establishes a closed-cycle experimental system and investigates jet impingement heat transfer characteristics with a microencapsulated phase change material (MEPCM) slurry as the working fluid. The phase change properties of the MEPCM particles and the thermal properties of the MEPCM slurry are analysed. The effects of several key parameters on the heat transfer and pressure drop of jet impingement are also discussed. Experimental results show that a 10% mass fraction of MEPCM slurry may enhance jet heat transfer by 32.8% compared with water because of the latent heat absorption of the PCM core. The heat transfer enhancement will be limited for higher mass fractions of slurry. The slurry exhibits a high heat transfer efficiency when the jet distance is ΔL/D = 4–9.3. The convective heat transfer coefficient of the slurry first increases and then decreases as the jet inlet temperature increases, and the optimum jet inlet temperature is approximately 12.1 °C lower than the melting peak temperature. Jet temperatures that are too high or too low will lead to deterioration of heat transfer for the slurry. These findings can provide guidance for the design of heat dissipation systems using MEPCM slurries.

The asymmetrical rolling (ASR) process with shear deformation is considered as a promising technology to adjust/improve through-thickness microstructure homogeneity and integrated properties of high-strength aluminium alloy plates. But the advantages may come with caveats that are the subject of our research. In this paper, the room-temperature low cycle fatigue properties and fracture behaviour of the ASR-ed AA7050 aluminium alloy plates are compared with the symmetrical rolling (SR) one. It is shown that after either type of rolling the plates exhibit similar low-cycle fatigue lives but the SR-ed one displays a better cyclic deformation ability and slightly higher fatigue lives at high strain amplitudes. It is demonstrated that the severe surface-localized deformation contributes to the formation of slip relief on the surface and subsequently initiates micro-cracks that are propagated via transgranular and/or intergranular fracture modes along with obvious fatigue striations. Recrystallised grains with coarse grain boundary precipitates and wide precipitate-free zones near the upper/bottom layers as well as numerous and larger secondary particles in the ASR-ed plates may cause early crack initiation for a short crack initiation life. However, the SR-ed plate with more frequent subgrains near surface layers, numerous fine subgrains and less indissoluble particles could possess better crack initiation/propagation resistance and cyclic loading behaviour. Fine subgrains with higher microhardness/strength can facilitate passing of dislocations or slip bands into adjacent grains so as to delay crack propagation such as via energy-intensified transgranular fracture for extending fatigue life. Properly balancing the through-thickness strain/deformation distribution and the formation of recrystallization/indissoluble particles via implementing a feasible ASR process becomes a critical issue to achieve fracture-resistant microstructures for high-strength aluminium alloy plates. The underlying causes/mechanisms regarding the differences of microstructures and mechanical behaviour are revealed and discussed based on modelling through-thickness temperature/strain distribution and detailed microstructure characterization.

Fe83.5B15Cu1.5Cax (x= 0.04, 0.07, 0.1 and 0.13) alloy ribbons were fabricated by melt spinning. The effects of Ca addition on electrical resistivity and soft magnetic properties were investigated. The results show that with increasing Ca content from 0.04 to 0.13 the electrical resistivity monotonously increases from 0.51 μΩ·m to 0.99 μΩ·m while the core loss reduced by 39% and 28% at 10 kHz and 20kHz under an applied magnetic field of 200 mT, respectively. After annealing at 420°C for 10min, sample with x=0.13 obtains the peak saturation induction density (Bs) of 1.82 T and coercive force (Hc) of 18 A/m. Especially, the core loss of sample x=0.13 decreased by 13% and 34% than that of x= 0.04 at 200 kHz under an applied magnetic field of 25 mT and 50 mT respectively. Therefore, the soft magnetic properties and core loss can be tuned by addition of Ca in Fe-B-Cu alloy ribbons.

The non-isothermal precipitation behaviors of Al–Mg–Si–Cu alloys with different Zn contents were investigated by differential scanning calorimetry (DSC) analysis, hardness measurement and high resolution transmission electron microscope characterization. The results show that Zn addition has a significant effect on the GP zone dissolution and precipitation of Al-Mg-Si-Cu alloys. And their activation energies change with the changes of Zn content and aging conditions. Precipitation kinetics can be improved by adding 0.5 wt% or 3.0 wt%Zn, while be suppressed after adding 1.5 wt%Zn. The Mg-Si precipitates (GP zones and β″) are still the main precipitates in the Al-Mg-Si-Cu alloys after heated up to 250 °C, and no Mg-Zn precipitates are observed in the Zn-added alloy due to the occurrence of Mg-Zn precipitates reversion. The measured age-hardening responses of the alloys are corresponding to the predicted results by the established precipitation kinetic equations. Additionally, a double-hump phenomenon of hardness appears in the artificial aging of pre-aged alloy with 3.0 wt% Zn addition, which resulted from the formation of pre-β″ and β″ precipitates. Finally, the precipitation mechanism of Al-Mg-Si-Cu alloys with different Zn contents was proposed based on the microstructure evolution and interaction forces between Mg, Si and Zn atoms.

Interface-reinforced Mg–6Zn–Zr/Mg–4Y-2Gd–Nd (wt. %) bimetal composites by long-period stacking ordered (LPSO) structures were fabricated and the interfacial microstructures and properties were investigated. Results revealed the presence of a (Mg, Zn)3RE phase (RE: Y, Nd, Gd), stacking faults, and variations in chemical composition at as-cast bonding interface. After heat treatment, interfacial LPSO structures, characterized as 14H and 24R types, were formed. The novel composites exhibited an interfacial shear strength superior to that of base metals and other light bimetal composites due to the generation of LPSO structures and kink-deformation bands. This finding provides a new approach for the design of high-performance bimetal composites.

To overcome the shortcomings of magnesium alloys such as low strength at an elevated temperature and poor corrosion resistance, the fabrication of Mg/Al compound materials has attracted more and more attention in the recent years. Among the various fabrication methods such as diffusion bonding, friction-stir welding, and fusion welding, insert molding technique has shown some advantages such as low production cost, short processing time and the ability of producing complex shape. However, there are only a few documents about this preparation method. In this paper, the corresponding study is carried out via inserting 6061 aluminum alloy into AZ31 magnesium alloy melt. The interface bonding mechanism and its mechanical behavior are investigated as well. It has been found that a good metallurgical bonding can be formed at the interface, which consists of three layers, i.e., Al 3 Mg 2 , Al 12 Mg 17 , and Al 12 Mg 17 +(Mg) eutectic structure. The average shear strength is 20 MPa, which is close to the reported shear strength of the samples prepared by other methods. This research provides a new insight for the fabrication of Mg/Al compound materials.

This paper is to explore a simple and effective experimental method to transform the bamboo’s hydrophobic property that enables them to achieve super hydrophobic effect. Soaking the experimental materials in nano-silicon dioxide solution is to prepare the super hydrophobic material. The particle size of silicon dioxide, contact angle of the transformed material, scanning electron microscope and energy spectrum were tested. The results show that the gas phrase nano-silicon dioxide solution is double microscopic particles which are advantageous to form the super hydrophobic structure. After transforming the property, both the contact angle of the outboard and inboard of bamboo can reach 150 degree or above, after transforming, there forms a super-hydrophobic thin film on the surface of bamboo material. The technology of forming a super hydrophobic structure on the surface of the gas phase nano-silicon dioxide is simple. This experiment is referentially meaningful in production.

Thirty clinical isolates of H. parasuis from pig farms in eastern China were screened for antimicrobial susceptibility. A novel plasmid, designated pHPSGC, was extracted from one isolate with evidence of resistance (elevated minimum inhibitory concentration) to florfenicol. DNA sequencing demonstrated that pHPSGC (5297 base pairs) contains three open reading frames (ORFs), corresponding to the genes rep, floR and lysR. The rep gene of pHPSGC shared 99% sequence identity with the rep gene of pHPS1019. In addition, the region containing floR and lysR in pHPSGC shared 99% similarity with the corresponding region of pCCK381. pHPSGC may be derived from a recombination event between pHPS1019 and pCCK381. A florfenicol resistance gene in H. parasuis may have been transferred via recombination between different plasmids.

Mitogen-activated protein kinase kinase kinase 5 (MAP3K5) is essential for apoptosis, proliferation, differentiation, and immune responses, and is a candidate marker for residual feed intake (RFI) in pig. We cloned the full-length cDNA sequence of porcine MAP3K5 by rapid-amplification of cDNA ends. The 5451-bp gene contains a 5'-untranslated region (UTR) (718 bp), a coding region (3738 bp), and a 3'-UTR (995 bp), and encodes a peptide of 1245 amino acids, which shares 97, 99, 97, 93, 91, and 84% sequence identity with cattle, sheep, human, mouse, chicken, and zebrafish MAP3K5, respectively. The deduced MAP3K5 protein sequence contains two conserved domains: a DUF4071 domain and a protein kinase domain. Phylogenetic analysis showed that porcine MAP3K5 forms a separate branch to vicugna and camel MAP3K5. Tissue expression analysis using real-time quantitative polymerase chain reaction (qRT-PCR) revealed that MAP3K5 was expressed in the heart, liver, spleen, lung, kidney, muscle, fat, pancrea, ileum, and stomach tissues. Copy number variation was detected for porcine MAP3K5 and validated by qRT-PCR. Furthermore, a significant increase in average copy number was detected in the low RFI group when compared to the high RFI group in a Duroc pig population. These results provide useful information regarding the influence of MAP3K5 on RFI in pigs.

D printing leads to the changes in manufacturing process, and the research and development of 3D printing supplies is considered as the core competitiveness of this technology. In this paper, it reveals the wood powder modification by establishing performance index of impulse process model to realize the dy- namic prediction. The wood powder after grinding can not be directly used for 3D printing, wood powder was modified under high temperature heat treatment in order to make the wood powder with even particle size, dispersed shape and good fluidity, which solve the main problems that wood powder can be employed as printing materials to 3D printing. But there were some disadvantages which would affect the 3D printing per- formance after the wood powder had been treated, its wettability degrading, sizing saturation reducing, densi- ty decreasing and color darkening. After the twice modification, it can obtain the modified parameters and technology by characterizing and analyzing the 7 indexes. KEYWORD: wood powder; 3D printing; high temperature heat treatment; hydrophilic fumed silica; pulse process model

Based on the densification of the spray-formed hypereutectic Al-Si (hyper-AS) alloys, the microstructural evolution, mechanical properties, as well as the failure are studied in this investigation. The appropriate process and parameters for the densification of the deposits are gained from the thermomechanical simulation. Besides of the spray-formed Al-25Si-5Fe-3Cu (3C) alloy, the microstructures of other spray-formed alloys with Mn/Cr addition are stable without coarsening of the refined α-Al(Fe,TM)Si (TM = Mn/Cr/(Mn+Cr)) particles, which can improve the heat resistance. Especially, a great number of the submicrosized α-Al(Fe,TM)Si phases are observed in the hot-extruded TM-containing alloys. The critical ranges of the major parameter TM/Fe mass ratios that can affect the formation of the α-Al(Fe,TM)Si phases in the cast or spray-formed hyper-AS alloys are severally determined. The structure and lattice constant of the refined α-Al(Fe,TM)Si phases also are characterized. The mechanical properties of the current extruded hyper-AS alloys at room or elevated temperatures are close to or higher than some commercial alloys or other published results. Therefore, the hyper-AS alloys can be proposed as new lightweight, heat-resistant, and high-strength alloys, which can be used in the complex working conditions, such as advanced engine systems. The main reason for the enhanced properties would be the formation of a large quantity of microsized/submicrosized α-Al(Fe,TM)Si phases and abundant dislocations, which can greatly reinforce the matrix and transform the brittle fracture of the needle-like Fe-bearing phases into ductile fracture.

In this work, a mixture of as-atomized and as-cryomilled powders instead of the pure as-cryomilled powder was used as feedstock to achieve high density nanocrystalline coatings by cold spraying. Cryomilled powder with nanocrystalline grains was produced by mechanical milling under liquid nitrogen and the grain size range was from 5 to 30 nm. A mixture of 30 wt.% as-atomized powder and 70 wt.% as-cryomilled powder was sprayed onto the aluminum substrates. High density coatings were attained by use of this kind of mixture, which was described as an effective method to decrease porosity in the cold-sprayed nanocrystalline coating. The functions of the as-atomized powder in the coating were discussed. The mechanical behavior of the powders and the coating were studied using nanoindentation technique.

The tetragonal TbPO4 was controlled synthesized via a simple solvothermal route by using glycol as solvent. The structures and micromorphologies of the as-synthesized TbPO4 have been investigated by means of X-ray powder diffraction (XRD) and field-emission scanning electronic microscopy (FE-SEM). The results showed that the tetragonal TbPO4 are composed of square-like particles about 200 nm in diameter. The photoluminescence spectra exhibited that the emission spectra of the sample could be divided into two parts, representing the 5D4 → 7FJ (J = 6, 5, 4, 3) transitions and 5D3 → 7FJ (J = 6, 5, 4, 3) transitions of Tb3+.

By using spray forming technique Fe-contained hypereutectic Al–Si alloys were prepared with different Mn/Cr additions for the study of their effects on the microstructures. The results show that adding 2 wt.% Mn/Cr separately can strikingly refine the Fe-bearing phase in spray-formed Al–25Si–5Fe–3Cu (wt.%) alloy into quantities of fine, uniformly distributed granular α-Al(Fe,Mn/Cr)Si phase, and Cr is more effective. But some short-plate Fe-bearing phases still exist in the spray-formed Al–Si alloys. Then, combined addition of Mn and Cr transforms these short-plate Fe-bearing phases into fine, granular α-Al(Fe,Mn,Cr)Si phase, promoting the appearance of almost single α-Al(Fe,Mn,Cr)Si phase in the spray-formed Al–Si alloys. Two mechanisms are proposed to elucidate the formation of α-Al(Fe,TM)Si phase (TM = Mn/Cr/(Mn + Cr)) during the solidification process: (1) transformed from metastable δ-Al(Fe,TM)Si phase in Mn/(Mn + Cr)-added alloys or (2) precipitated from liquids directly in Cr-containing alloys. Because the strong interactions and isomorphic substitution among different TM elements, the metastable δ-Al(Fe,TM)Si phase (clusters) can be precipitated from the liquids and transformed into stable α-Al(Fe,Mn,Cr)Si phase in Mn- or (Mn + Cr)-added alloys. The stable α-Al(Fe,Cr)Si phase can precipitate directly from the liquids because no metastable ternary intermetallics exist in Al–Cr–Si system and can be transformed into stable α-AlCrSi phase. Also the high segregation temperature of Cr in liquid Al melts promotes the microsegregation of Cr and formation of (AlCrSi) clusters/intermetallics in Cr-added alloys. As a result, both metastable δ-Al(Fe,TM)Si phase (clusters) and stable α-Al(Fe,TM)Si phase (clusters) can be present in (Mn + Cr)-added alloys. With further solidification, these clusters become the nucleation sites and grow up unceasingly. The coexistence of the nucleus of δ-Al(Fe,TM)Si and α-Al(Fe,TM)Si phases in the liquid alloys can induce the simultaneous presence of these two phases in atomized droplets or particles. With continuous deposition of atomized droplets or particles, the appearance of mushy zone on the surface of preforms promotes the transformation of metastable δ-Al(Fe,TM)Si phase into stable α-Al(Fe,TM)Si phase, especially inducing the ideal case featured by single α-Al(Fe,TM)Si phase. It is concluded that the improvements of the thermal stability of present hypereutectic Al–Si alloys are attributed to the increment of solidus temperatures and the presence of the granular α-Al(Fe,TM)Si phase with high dissolution temperature induced by TM addition.

Hexagonal CePO4 nanowires with a high aspect ratio were controllably synthesized through an oxalate-induced hydrothermal route. The hexagonal CePO4 and CePO4:Tb nanowires exhibited highly enhanced photoluminescence. The organic ligand oxalate was found to play a role for the oriented growth of the nanowires, as well as the structure evolution. The synthesis of nanostructured CePO4 with hexagonal and monoclinic structures was controlled by varying the C2O42-/Ce3+ molar ratios. A formation mechanism of the morphology and crystal structure was proposed. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

4 blades PCD combined tool used for hole reaming and chamfer milling Al-alloy cylinder block has been developed. Results showed that the tool life of this PCD tool is 21.5 times than the former carbide tools made by Japanese company, the surface roughness of the hole is Ra0.2, better than the required Ra3.2, the 90 chamfer surface roughness is Ra1.6, better than the required Ra25.

Cam is the key component of many important types of equipment. To improve the surface precision of cam, and to eliminate the cutter track, the production data format is analyzed in this paper, a conclusion that the big second derivative is the origin of track is reached. An algorithm to eliminate cutter track is brought forward, spline curve fitting is used to process the discreted data, and spline interpolation is used hereafter such that the second derivative is reduced to an acceptable range. The experiment shows that this method can efficiently eliminate the track on the surface, so as to improve the productivity of equipments.

Microstructures and thermal stability of hypereutectic Al–Si alloys with or without (Mn + Cr) addition, prepared via Spray Forming technique, are studied and compared with traditional cast alloys with same composition, using scanning electron microscopy with energy diffraction spectrum, X-ray diffraction, transmission electron microscopy and differential scanning calorimeter. The results show that the Fe-bearing and primary silicon phases in SF-3C alloy can be refined to less than 10 μm, especially in SF-MC21 alloy the Fe-bearing phase is refined into uniformly distributed α-Al(Fe,Mn,Cr)Si phase particles with sizes smaller than 5–6 μm, contributing to the decrease/elimination of the deleterious effect of needle-like Fe-bearing phases. The results of different heat treatments show SF-MC21 alloy possesses excellent thermal stability than SF-3C alloy which is unstable below 750 K for the coarsening of β-Al5FeSi phase and formation of Al7Cu2Fe phase. The study indicates that both the existence of thermodynamically stable α-Al(Fe,Mn,Cr)Si particles and the increase of solidus temperature of SF-3C alloy induced by adding (2Mn + 1Cr) elements contribute to the high thermal stability of SF-MC21 alloy. Contemporarily, combined the phase reactions or transformation occurred during the melting and solidification processes of both spray-formed hypereutectic Al–Si alloys, the microstructure formation of spray-formed alloys is discussed.

Nanostructured terbium orthophosphate (TbPO(4)center dot H(2)O) nanostructures with enhanced photoluminescence were prepared through a controlled, simple, and template-free hydrothermal route. The structures and micromorphologies of the as-synthesized TbPO(4)center dot H(2)O were investigated by X-ray powder diffraction (XRD), thermogravimetric analysis, differential scanning calorimetry (TG-DSC), field-emission scanning electronic microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS). The results showed that the TbPO(4)center dot H(2)O spindle-like hierarchical nanostructures are composed of ordered nanorods of 80-90 nm in diameter and lengths of up to 200-300 nm. It was found that the reactant molar ratios and pH values played key roles in the morphology control of the product. A possible formation mechanism for the spindle-like morphology is also proposed. A photoluminescence study of the products indicated that the self-assembled spindle-like nanostructures display better photoluminescence than TbPO(4)center dot H(2)O that was synthesized on both the nano- and microscale. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The hypereutectic Al–25Si–xFe–yMn alloys (with the ratio of Mn to Fe (y/x) between 0 and 1 wt.%) were synthesized by spray forming. The microstructure of the spray-deposited preforms as well as the over-sprayed powders was investigated. The addition of Mn was aimed to improve the mechanical properties of the alloys through forming the particulate α-Al15(Fe,Mn)3Si2 phase to replace the acicular δ-Al4FeSi2 and β-Al5FeSi phases formed in the alloy without Mn. XRD results revealed that, for alloy with y/x = 0, almost single acicular δ-Al4FeSi2 phase presented in the over-sprayed powders, whereas the spray-deposited preform consisted of both δ-Al4FeSi2 and β-Al5FeSi phases. For alloy with y/x = 0.625, the particulate α-Al15(Fe,Mn)3Si2 phase began to appear in the deposited preform. When y/x increased to 1.0, δ-Al4(Fe,Mn)Si2, β-Al5(Fe,Mn)Si and α-Al15(Fe,Mn)3Si2 phases coexisted in the over-sprayed powders, whereas only particulate α-Al15(Fe,Mn)3Si2 phase could be observed in the deposited preform. These results can be explained with schematics for transformation of the intermetallics in light of the phase forming mechanisms involved during spray deposition.