Effect of Rare Earths on Microstructure and Properties of TiC-based Cermet/Cu Alloy Composite Wear Resistant Materials

The effect of rare earth (RE) oxide on the microstructure and properties of TiC based cermet/Cu alloy composite hardfacing materials was investigated by using scanning electron microscope (SEM), transmission electron microscope (TEM), impact test and wear test. The mechanism of RE oxide for improving the phase structure and the impact toughness was also discussed. The experimental results indicate that the microstructure of the matrix can be refined, and the micro-porous defects can be eliminated by adding RE oxide into the composite materials. The polycrystalline and amorphous phase structure is formed at the interface of cermet and matrix metal. The formed structure enhances the conjoint strength of interface. The frictional wear resistance can be improved obviously, although the microhardness of the matrix metal can not be effectively increased by adding RE oxide.

Study on Rare Earth-Containing Phases in TiAl Based Alloys Prepared by Non-Equilibrium Solidification Processing

Microstructure evolution of rare earth rich phase of rapidly-solidified (RS) TiAl based alloys was investigated. The two rapid-solidification techniques employed are melt-spinning technique (MS) and Hammer-and-Anvil technique (HB). MS ribbons and HA foils were obtained in the experiment. The results demonstrate that with the increasing of cooling rates of TiAl based alloys great changes are taken place in the microstructures of rare earth rich phase, from scattering mainly on grain boundaries of as-cast ingot to distributing homogeneously as very fine fibers or powders (nanometer grade) on the matrix. The fine paralleling second phase fibers in the HA foils are considered to be connected with gamma/alpha (2) lamellar colonies. Selected area electronic diffraction (SAED) patterns of the rare earth rich phase is in accordance with that of intermetallic AlCe.

Study on Particle Size and Electrochemical Properties of Rare Earth Based Hydrogen Storage Alloys

The rare earth based hydrogen storage alloys Ml_ 0.7Mm_ 0.3(Ni_ 3.55Co_ 0.75Mn_ 0.4Al_ 0.3) were chosen as objects of investigation in this paper. The effects of particle size on electrochemical properties of the alloy were investigated. The results indicate that the alloy with particle size of 100 and 150 mesh shows good activation behavior and high discharge capacity (the first discharge capacity and the maximum discharge capacity), but poor cycling stability, low capacity retention and high discharge capacity rate. The Ml_ 0.7Mm_ 0.3(Ni_ 3.55Co_ 0.75Mn_ 0.4Al_ 0.3) alloy with particle size of 150 mesh shows excellent electrochemical properties.

EFFECT OF RARE EARTH ELEMENT Er ON STRENGTHENING OF INTERFACE OF Ti（C，N） BASED CERMETS

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Phase Structure and Electrochemical Properties of Rare Earth Based Hydrogen Storage Alloys

The rare earth based hydrogen storage alloys MmxM1 1 - x ( Ni3.55 Co0.75 Mn0.4 A10.3 ) ( x = 0 ～ 0.5 ) were investigated in this work.Adjusted Ml: Mm ratio to change the content of La,Ce,Pr and Nd in the alloys and then to change the phase structure, the influences of phase structure on the electrochemical properties were analyzed.The results indicate that the main phase of all alloys is LaNi5 with CaCu5 type structure and the crystal lattices constants of LaNi5 are changed with increasing x value, i.e, decreased a-axis, increased c-axis and axis ratio and nonlinear decreased crystal volume.The crystal volume of the alloy with x = 0.3 is larger than others.There is second phase A1LaNi4 in alloys when x≥0.3, which decrease the discharge capacity, but increase the cycling stability and high rate discharge ability.Compared comprehensively, the alloy with x = 0.3 shows the higher discharge capacity and the better cycling stability.

Effect of Rare Earth on Microstructure of Vacuum Melting Ni-Based Self-Fluxing Alloy Coatings

The Ni-based self-fluxing alloy coating containing RE was acquired by the technique of vacuum melting on the hypoeutectoid steel (Fe-0.45%C) matrix. By X-ray diffraction, SEM and EDX, the microstructure and phase structure of section of coating and the microstructure near the interface between coating and matrix were investigated, and the effect of RE on microstructure of coating was also discussed. The results show that the microstructure of the NiCrBSi alloy coating is composed of Ni-based solid solution and a lot of massive, globular and needle secondary phases CrB, Ni_3B, Cr_7C_3, Cr_(23)C_6 among the solid solution. The metallurgical binding between steel matrix and coating is realized. RE makes needle phase of alloy coating vanish. New phases of NiB and Cr_(6.5)Ni_(2.5)Si are precipitated from alloy coating, and secondary phases of alloy coating are sphericized. Consequently, RE also hinders the diffusion of Ni, Cr and Si atoms from coating to matrix and Fe atoms from matrix to coating, holds back the dilution of Fe for NiCrBSi alloy coating, and assures the chemical composition of the alloy coating.

Effect of Roasting Conditions of Rich Cerium Rare Earth Carbonate on Crystallite Morphology and Polishing Ability of Ceria-Based Rare Earth Oxide

The granule shape and crystal structure of the the ceria-based rare earth oxide which were roasted at 600～1050 ℃ for 2～6 h and then cooled in furnace, cooled out of furnace or cooled in water were studied by means of XRD and SEM. The results revealed that the rich cerium rare earth carbonate could be changed into the rare earth oxide which was a kind of sandwich made of globose granule whose diameter was between 0.5～3.0 μm after being roasted in 900 ℃ for 2 h. This kind of crystal lattice in rare earth oxide belonged to face-centered cubic lattice and its space between crystal surface {111} and {200} (viz. L111 and L200) would enlarge as the roasting temperature increasing. With increasing roasting temperature, L111 would rise straightly upward, and L200 would rise straightly upward when roasting time was 2～4 h but changed little when roasting time was 4～6 h. The glass-polishing experiments found that the polishing ability of the ceria-based rare earth oxide was the best as L111 was 43～53 nm and the L200 was 43～56 nm.

Effect of Heat-Treatment Process on Properties of Rare Earth Mg-Based System Hydrogen Storage Alloys with AB_3-Type

The effect of heat-treatment process on the properties of Mm0.8Mg0.2(NiCoAlMn)3.5 hydrogen storage alloy was discussed . The electrochemical properties such as cycling stability, activation property, and the plateau voltage of the alloy which was heat-treated in various temperatures and times had different changes during the cycle process, the optimum heat-treatment conditions of this alloy were determined by this work.

Study on Nanocrystalline Rare Earth Mg-Based System Hydrogen Storage Alloys with AB_3-Type

A sort of rare earth Mg-based system hydrogen storage alloys with AB3-type was prepared by double-roller rapid quenching method. The alloys were nanocrystalline multi-phase structures composed of LaNi3 phase and LaNi5 phase by X-ray diffraction and scanning electron microscopy analyses, and the suitable absorption/desorption plateau was revealed by the measurement of P-C-I curve. Electrochemical studies indicate that the alloys exhibit good electrochemical properties such as high capacity and stable cycle life, and the discharge capacity is 369 mAh·g-1 at 0.2 C (72 mA·g-1). after 460 cycles, the capacity decay was only 19.4% at 2 C (720 mA·g-1).

Mechanism of interaction relation between the rare-earth element Ce and impurity elements Pb and Bi in Ag-based filler metal

The mechanism of interaction relation between the rare-earth element Ce and elements Pb and Bi in Ag-based filler metal has been studied. The results show that the compounds CePb and CeBi with high melting point can be easily produced between these three elements in the filler metal, which greatly limited the formation of the isolated phase Pb or Bi and also eliminated the bad effect of impurity elements Pb and Bi on the spreading property of Ag-based filler metal. The metallurgical and quantum-mechanical bond formation analysis show that a strong chemical affinity was existed between the rare-earth element Ce and impurity elements Pb and Bi, which was proved by the XRD analysis results.

FORMATION OF GRADIENT COATING OF Fe-BASED ALLOY WITH RARE EARTHS BY PLASMA SURFACING

A gradient coating of Fe-based alloy was manufactured with rare earths (RE) by plasma surfacing on Q235 steel substrate. The coatings were studied by using X-ray diffraction(XRD), scanning electron microscope(SEM), differential thermal analyzer(DTA), and electron probe micro-analyzer (EPMA). The results show that the phases of the two kinds of coatings(with and without RE) both include α-Fe, Fe7C3, Fe3C, Cr2B, Fe2B and FeB. The microstructure of F314 coating is mainly hypereutectic, the pro-phases Cr7C3 and Cr2B are loose, crassi, spiculate and contain microcracks. The brittleness of the coating is high, and the average hardness is 787 HV. When 0.8wt% RE was added into the F314 alloy, the microstructure varied from hypoeutectic to hypereutectic continuously, The hardness appears as gradient distribution with the highest value of 773 HV, meanwhile, the brittleness decreases significantly. The formation of gradient structure depends on the fallowing factors: (i) the conversion of RE. The addition of RE lowers the elements point and Fe-C eutectic temperature, thus the base metal melting acutely. (ii) the heating of plasma arc. Graded temperature results in directional solidification, thus the gradient structure forms easily. The main reasons for the hardness decrease with RE addition in the alloy are the ratio of hard phase lowering and the hardness of the hard phase decreasing.

Effect of Rare Earth on the Corrosion-Resisting Performance of Zinc-Based Alloy Coatings

The corrosion behavior of coatings of pure zinc and Zn-Al,Zn-Al-RE alloys in NaCl solu- tions was studied by salt-spray experiments,even corrosion experiments and electrochemical measurements of bi-directional polarization curves and a.c.impedance in weak polarization region consistent regularities were obtained by these different methods,viz.,the corrosion resistance of Zn could be enhanced by alloying it with Al,and particularly with Al-RE.The causes of enhancement of corrosion resistance by RE were also discussed.

Study on Phase Structure and PCT Characteristics of Rare Earth Based Hydrogen Storage Alloys

The rare earth based hydrogen storage alloys Mm_xMl_ 1-xNi_ 3.55Co_ 0.75Mn_ 0.4Al_ 0.3(x=0～0.50) were investigated in this work. The influences of phase structure on the PCT characteristics were analyzed by means of electrochemical measurements. The results indicate that there is a strict relationship between crystal volume and PCT characteristics.

Formability of Rare Earth-Containing Solid Solution Based on Compounds with Scheelite-Type Structure

The regularities of the solid solutions between the scheelite-type compounds and rare earth molybdates or tungstates were investigated by the atomic parameter-support vector machine method and the intelligent database of phase diagrams of molten salt systems. The crystal structure of scheelite-type compounds having M^1M^′Ⅲ （XO4）2（X = Mo, W） as common formula and the formability of the continuous solid solution between these compounds and rare earth molybdates or tungstates were also investigated. Besides, the cell constants of these compounds can be calculated by some semi-empirical equations. Based on the obtained relationships, the results of computerized prediction of the solid solubility of T1Pr （MoO4）2-Pr2 （MoO4）3 system have good agreement with experimental results.

Study of Bi_2O_3-based Rare Earth Solid Electrolyte Used in Fuel Cell

Solid ceramic electrolyte materials (Bi_2O_3)_(0.75)(Y_2O_3)_(0.25) and(Bi_2O_3)_(0.65)(Gd_2O_3 )_(0.35)were synthesized.Their crystal structure, XPS spectra and the change of ionic conductivity versus temperature were measured.A Bi_2O_3-based rare earth solid electrolyte fuel cell with ZrO_2-Y_2O_3 protection film was made.

Cluster Based Strategy to Improve Competitiveness of Rare Earth Industry in China——Taking Emerging Rare Earth Industry Cluster in Baotou As An Example

China′s rare earth industry has shown its strong competence, but notably this competence is mostly based on the comparative advantages in natural resources and production costs that will not provide a long-term momentum for the growth of the industrial competitiveness. It has become an urgent task now for China′s rare earth industry to improve its competitiveness through adjusting the product structure and enhancing the technological application, to gain much healthier and more sustainable growth in the future. This paper aims to present a new development strategy based on the industry cluster theory to improve the competitiveness of China′s rare earth industry with a case study on the emerging rare earth industry cluster in Baotou. The paper first reviews the cluster theory and explains why it matters to industrial competitiveness briefly, and then proposes a general framework for implementing cluster policies and strategies in practice. Following that, a case to study the emerging rare earth industry cluster in Baotou was presented and a cluster initiative based on the general framework was developed. The objectives of the cluster initiative and the role of government on initiative organizing and cluster upgrading were discussed in detail. In the end, general implications drawn from the case of Baotou were summarized, which try to provide some insights for applying cluster-based strategies to the rare earth industry of China.

Synthesis, characterization, and anticancer properties of rare earth complexes with Schiff base and o-phenanthroline

Five novel ternary complexes of the rare earth ions with o-phenanthroline（Phen） and Schiff base salicylaldehyde L-phenyla- lanine（KHL） were synthesized in ethanol. Their compositions were characterized by elemental analysis, molar conductance, ^1H NMR, FT-IR, and Raman spectra. The formulas of the complexes were verified to be RE（L）（Phen）Cl（H2O） （RE=La^3＋, Ce^3＋, Nd^3＋, Er^3＋, and Gd^3＋; L=Schiff base salicylaldehyde L-phenylalanine; phen=o-phenanthroline）. Methyl thiazolyl tetrazolium （MTT） colorimetry and flow cytometry were used to test the anticancer effect of the complexes with K562 tumor cell. The research showed that the complexes could inhibit K562 tumor cell＇s growth, generation, and induce apoptosis. The inhibition ratio was accelerated by increasing the dosage, and it had significant positive correlation with the medication dosage.

Enhancement of comprehensive properties of Nb-Si based in-situ composites by Ho rare earth doping

This study examines the microstructure,mechanical properties(with a focus on room-temperature toughness),and oxidation resistance of Ho-doped NbDSi based in-situ composites.The base alloy consists of the coarse primary Nb_(5)Si_(3)phase and the Nb_(5)Si_(3)+Nbss(Nb solid solution)eutectic cells.Ho doping influences the solidification path.When the Ho doping is higher than0.2 at%,the alloys transform into eutectic alloys.Ho can be solid-solved in trace amounts in the Nbss phase.However,most of Ho forms a stable Ho oxide phase,which alleviates oxygen contamination problem to some extent.Moreover,the interface separation between Ho oxide and other phases reduces the plastic deformation constraint.Thus,with 0.4 at%Ho doping,the K_(Q)value is18.03 MPa·m^(1/2),which is 31.1%higher than that of the base alloy.The strength of the Ho-doped alloys does not deteriorate with an increase in toughness.However,the large network-like Ho_(2)O_(3)in the 0.8Ho alloy causes a decrease in toughness and strength.In addition,the Ho oxide phase effectively blocks the inward oxygen intrusion.With 0.8 at%Ho doping,the oxidation mass gain per unit area is 10.16 mg·cm^(2),which is 39.7%lower than that of the base alloy.

Synthesis, Characterization and Bioactivity of Complexes of Rare Earth with Bis-Schiff Base from Furoylpyrazolone

Eleven new complexes of rare earths with bis-Schiff base derived from N,N'-bis[(1-phenyl-3-methyl-5-oxo-4-pyrazolinyl) alpha-furylmethylidyne] ethylenediimine ((HPM alpha FP)(2)en) were synthesized. On the basis of elemental analysis and molar conductance, a general formula of the complexes, [RE(HPM alpha FP)(2)en(NO3)(2)]NO3(RE = La, Pr, Nd, Sm, Eu, Th, Dy, Ho, Er, Yb,Y), was given. The complexes were characterized by IR, UV-visible, H-1 NMR, C-13 NMR and fluorescence. The results show that the bis-Schiff base is a quadridentate ligand and the rare earth ions exhibit coordination of eight in the complexes. The antibacterial experiments indicate that they have high antibacterial activities against S. aureus, B. subtillis, E. coli, E. carotovora, C. flaccumfaciens.