Enhancing strength and ductility in back extruded WE71 magnesium alloy cylindrical parts by introduction of multi-direction forging process

Magnesium cylindrical parts have relatively poor mechanical properties and distinct anisotropy of microstructure,which hinder their application as structural components.To improve the performance of WE71 cylindrical parts,multi-direction forging(MDF) was introduced before back extrusion,and the microstructure and mechanical properties were investigated.Results of microstructure show that the grain size in the outer of the cylindrical bottom is refined from 30.1 to 27.7 μm,the micro structure is ...     

Electrical and dielectric properties of Ni0.5Co0.5GaxFe1.8-xO4(x≤1.0)spinel ferrite microspheres

Microspheres of Ni_0.5 Co_0.5Ga_xFe_2-xO₄(x≤1.0) microsphere spinel ferrites(NiCoGaFe-MSFs) and carbon spheres were prepared via a hydrothermal technique.The micro structure of microspheres was investigated through scanning and transmission electron microscopy(SEM and TEM),respectively,and X-ray diffraction(XRD).The electrical and dielectric properties of NiCoGaFe-MSF at temperatures ranging from20 to 120℃(between 293,1× 10³ and 393.1...     

Structural,morphological and photoluminescence characterizations of Sm3+ doped Y2O3 nano-sized phosphors synthesized by ultrasound assisted sol-gel method

Nanosized 1 at% Sm³⁺doped Y₂O₃ powders were prepared by an ultrasound assisted sol-gel method.Y₂O₃:Sm³⁺powders crystallize in Y₂ O₃ pure cubic phase and XRD analysis shows that the as-used agitation protocol affects strongly the crystallite’s shape and mean size.The recorded emission spectra under λ_em=600 nm exhibit two absorption bands;the first one is assigned to O^2-→Sm³⁺cha...     

Surface hardness,thermal,optical,and photon attenuation coefficients assessment for dysprosium-doped tellurite glasses

Using a melt-cooling process with the host glass,Dy₂O₃(1 wt%,2 wt%,3 wt%,and 4 wt%) doped tellurite glasses were produced.A(65-x)TeO₂-20B₂O₃-10Al₂O₃-SGeO₂-xDy₂O₃ glass system was analyzed by Xray diffraction.The patterns have a hump at 2θ=27°-29° and no sharp peaks,indicating that all the glass samples are amorphous.The Vickers microhardness determines how resistant a glass is to persist...     

A novel Ga(Ⅲ)coordination complex as an efficient sensitizer for enhancing photocatalytic activity of TiO2/rGO nanocomposite

Narrow solar-light response range and rapid charges recombination are the main technical barriers in TiO₂ photocatalysis technology.To overcome these restrictions,in this work we synthesized a novel binuclear gadolinium(Ⅲ) coordination complex,[Gd₂(DPDB)₆(DMF)₆(H₂O2)](DPDB=[(4-dimethylamino)phenyldiazenyl] benzenesulfonate),which was used as an inorganic sensitizer for boosting the visible light-harvesting and quantum efficiency o...     

Phosphorus fixation capacity of CaO-SiO2-Al2O3-MnO-Ce2O3 slag based on structural considerations

The phosphorus fixation capacity of some slag systems,such as Ce₂O₃-containing slag,has hardly been investigated from a thermodynamics view due to the lack of relevant thermodynamic data.Since the macroscopic properties are primarily determined by the microscopic structure,the correlation between phosphorus fixation capacity and slag structure was explored by spectroscopy(XPS),Raman spectroscopy,and ferromanganese dephosphorization experiments.The results show that the pred...     

Crystal growth,structure and laser performance of a new Yb~(3+):KBaY(MoO_4)_3 crystal

A Yb~(3+):KBaY(MoO_4)_3(Yb3+:KBYM) crystal with dimensions of 51 mm × 27 mm x 10 mm was successfully grown by the TSSG method.The characteristics of the crystal structure and probability of good optical properties were analyzed.The absorption and emission spectra of Yb3+:KBYM crystal exhibit broadened bands,with the maximum absorption cross-sections of 1.17 x 10~(-20),1.44 ×10~(-20) and 1.37 x 10-20 cm~2 at976 nm for X-,Y-and Z-polarizations,respectively.The corresponding absorption FWHMs are as wide as 77,46 and 55 nm.The well-known re-absorption effect of Yb3+in the crystal is discussed.Two methods,the Fiichtbauer-Ladenburg method(FL) and reciprocity method(RM) were adopted to compute the emission cross-sections and results show a certain discrepancy but the errors are allowable.The laser potentiality of the Yb3+:KBYM crystal was also evaluated by calculations of minimum inversion fraction β_(min),saturation pump intensity I_(sat),the minimum pump intensity I_(min) and gain cross-sections spectra.Laser experiment was carried out and Watt-level continuous wave laser has been realized.Results indicate that the Yb~(3+):KBYM crystal with a disordered structure may be a potential laser media that can be used to generate tunable and ultrashort pulse laser emissions with high quality beam.     

Tb~(3+) substituted strontium hexaferrites:Structural,magnetic and optical investigation and cation distribution

In this study,SrFe_(12-x)Tb_xO_(19)(0.00≤x≤0.1) hexaferrites(HFs) were prepared successfully by citrate solgel approach.X-ray powder diffraction analyses affirm the hexagonal structure of products.Impurity phase starts to appear for x≥0.04.The crystallites sizes were estimated to be in the range of 33-46 nm.All the products exhibit inhomogeneous distribution of grain size detected through SEM.The analyses of magnetization versus applied magnetic field,M(H),were performed.Magnetization measurements were done at room(300 K;RT) and low(10 K) temperatures.The different magnetic parameters including saturation magnetization M_s,remanence M_r,squareness ratio(SQR=M_r/M_s),coercivity H_c,and magnetic moment n_B are deduced and discussed in detail.At both considered temperatures,M(H) results show ferrimagnetic nature for all compositions.It is shown that the Tb substitutions significantly affect M(H)data.A significant increase in the M_s,M_r,and n_B is observed for x=0.02 sample.The SQR values are around 0.5 indicating the single domain nature with uniaxial anisotropy.The obtained magnetic results were investigated deeply with relation to structural and microstructural properties.Mossbauer spectroscopy results were also investigated.According to Mossbauer results,the Tb~(3+) ions preferentially occupy 12 k and 4f_2 sites.     

Structure,magnetism and magnetic thermal properties of heavy rare earth Tb_(1-x)Tm_xFeO_3(x=0.00,0.15,0.25) polycrystalline samples

Tb_(1-x)Tm_xFeO_3(x = 0.00,0.15,0.25) polycrystalline series were synthesized using a solid-state reaction.Our results show that all three prepared samples are in a distorted orthogonal structure and their space group is pbnm.When the Tm~(3+)doping amount increases,the characteristics of the spin-flip of the sample decreases following an initial increase at the beginning;the antiferromagnetic property almost reaches zero;the magnetization decreases at the beginning but increases later on.The maximum magnetic entropy change and magnetic refrigeration effect RCP are reduced at varying degrees.Under a 7 T magnetic field,the maximum magnetic entropy change,△S_(max),for the three samples of Tb_(1-x)Tm_xFeO_3 with x=0.00,0.15,0.25 is 13.78,-9.28,and 10.69 J/(K·kg),respectively;the magnetic refrigeration capacity(RCP) is 316.85,175.2,and 297.60 J/kg,respectively.In summary,doping with the element Tm reduces △S_(max) and RCP of the sample.Since the maximum magnetic entropy change and the cooling capacity for the three samples are relatively large,they can be used as an alternative for magnetic refrigerants.     

Electrical conductivity of REF_3-LiF(RE=La and Nd) molten salts

The electrical conductivity of REF3-LiF(RE=La and Nd) molten salts(xREF_3=5 mol%-40 mol%) was systematically measured over the temperature range from 1223 to 1423 K by using continuously varying cell constant(CVCC) method.Electrical conductivity values of LaF3-LiF and NdF_3-LiF molten salts within the studied ranges are 4.11-9.39 and 3.62-9.51 S/cm,respectively.The composition and temperature dependences of electrical conductivity and the factor of RE_2 O_3 on electrical conductivity were investigated.The electrical conductivity nonlinearly decreases with the increasing mole percent of REF_3 for the changing of structural ion in molten salts.A good linear relationship between the natural logarithm of electrical conductivity(lnκ) and the reciprocal of the absolute temperature(T~(-1)) can be interpreted by the trend that electrical conductivity linearly increases with increasing temperature.Although it is an important factor of RE_2 O_3 on electrical conductivity,the influence of RE_2 O_3 on conductivity is small for the very limited solubility of RE_2 O_3 in REF_3-LiF molten salts.The results of this work supplement the present electrical conductivity data of rare earth fluoride electrolyte.     

Nucleation and growth of L12-Al3RE particles in aluminum alloys:A first-principles study

The internal mechanisms of nucleation and growth of L1₂-AI₃RE(RE=Sc,Y,La-Lu) second phases in Al alloys were investigated by combining first-principles calculations with quasi-harmonic approximation(QHA).The calculated results show that the diffusion rate D_s and chemical potential AG_V increase with the increase of temperature.With the increase of atomic number,the D_s and the strain energy ΔE_CSincrease firstly from Sc to La,and the...     

Catalytic conversion and DFT analysis of post DDBD-catalysis system for degradation of toluene,ethyl acetate and acetone with different metal-oxides catalysts

A series of multiphase metal-oxide catalysts(MnO_x/γ-Al₂O₃,CuO_x/γ-Al₂O₃,FeO_x/γ-Al₂O₃,CeO_x/γ-Al₂O₃and LaO_x/γ-Al₂O₃) were prepared for plasma-catalyst degradation of multicomponent volatile organic compounds(VOCs,such as toluene,acetone and ethyl acetate).The results reveal that the degradation efficiency(DE) of acetone,toluene and ethy...