Increase Of Rare Earth Content Research Articles

Quantitative analysis of rare earth elements in Mg–Zn–RE(Ce, Y, Gd)–Zr alloy

The solid solution amount of rare earth elements and the mass fraction of compounds were measured by low-temperature phase separation technology, the existing forms of rare earth elements in ZK-RE(Ce, Y, Gd) alloy were quantitatively studied, and the difference of solid solution ability of rare earth elements and the factors affecting the number of rare earth compounds were analyzed. The experimental results show that the solid solution amount of rare earth elements mainly depends on their addition amount, Zn and RE inhibit each other’s solid solution amount, and the order of solid solution amount (wt%) of rare earth elements with the same addition amount is GD > Y > Ce. Rare earth elements are mostly distributed in Mg–Zn–RE compounds, and the increase of rare earth content is helpful to form more Mg–Zn–RE compounds. With the same content of elements, the order of mass fraction of Mg–Zn–RE compounds is ZK-Ce system > ZK-Y system > ZK-Gd system. The order of solid solution ability of rare earth elements is Gd > Y > Ce, and the amount of solid solution directly affects the initial element content of compound precipitation in the remaining melt. The influence of Zn/Ce ratio in the residual melt of ZK-Ce alloy is shown in the number of rare earth compounds, while the Zn/Y(Gd) ratio in the residual melt of ZK-RE(Y, Gd) alloy determines the type and number of rare earth compounds.

Effects of rare earth elements (Ce, La) on microstructure and mechanical properties in compacted graphite iron

ABSTRACT Microstructure and mechanical properties of compacted graphite iron (CGI) alloyed with different additions of rare earth (RE) elements are analysed in this paper. Experimental results show that graphite presents mostly vermicular shape when the content of RE is less than 0.041%. The shape of graphite becomes spherical after more RE is added. Tensile strength is improved significantly with the increase of RE content at room temperature and 400°C. Growth rate of main crack decreases obviously after RE alloying during thermal fatigue tests at 600°C. RE elements tend to segregate towards the interface between graphite and matrix, which leads to the change of graphite morphology. Auger electron spectroscopy (AES) results also show that Ce atoms will concentrate towards fracture surface, thus improving the oxidation resistance of the fracture surface at high temperature and crack propagation is inhibited.

Effect of Rare Earth on M7C3 Eutectic Carbide in 13% Chromium Alloy Cast Iron

The crystallization process of hypoeutectic white cast iron consists of the first secreted austenite branch after the reaction of the austenite -carbide crystal is formed, and the phase crystal fills in the middle of the austenite branches. If the austenite branches are small and smooth, the crystals carbide are fine. The cast iron with 13% chromium which has 3 - 3.2% carbon, have the carbide crystalline as M7C3. The elements in rare earth have a strong affinity for oxygen and sulfur to produce rare earth oxides. These rare earth oxides can create heterogeneous germ center for austenite phases and smooth down these phases. The effect of rare earth on the M7C3 and crystals of 13% chrome white iron has been elucidated. Along with the increase of rare earth content, the microstructure of M7C3 with fine finely graded, more uniformly distributed, dispersed throughout the sample surface. When the carbide is fine and dispersion, will contribute to improving the properties of cast iron especially the impact strength as well as the abrasion resistance of the alloy. The research results show that in the presence of rare earth, rare earth elements created with oxygen and form La2O3 and Ce2O3 as the nucleation for the solidification process and create the small fineness of phases. The orientation of the crystal structure of these oxides is similar to the crystal structure orientation of Fe-γ phase. Finding and proving the oxides of rare earth has crystal structure with phase γ which will be small smooth exogenous minds that the microstructure has a smooth, small size.

Effects of rare earth elements on inclusions and impact toughness of high-carbon chromium bearing steel

High-carbon chromium bearing steels with different rare earth (RE) contents were prepared to investigate the effects of RE on inclusions and impact toughness by different techniques. The results showed that RE addition could modify irregular Al2O3 and MnS into regular RE inclusions. With the increase of RE content, the reaction sequence of RE and potential inclusion forming elements should be O, S, As, P and C successively. RE inclusions containing C might precipitate in molten steel and solid state, but the precipitation temperature was significantly higher than that of carbides in high-carbon chromium bearing steel. For experimental bearing steels, the volume fraction of inclusions increased steadily with the increase of RE content, but smaller and more dispersed inclusions could be obtained by 0.018% RE content compared with bearing steel without RE, whereas the continuous increase of RE content led to an increasing trend for inclusion size and a gradual deterioration for inclusion distribution. RE addition could improve the transverse impact toughness and isotropy of bearing steel, and for modified high-carbon chromium bearing steel by RE alloying, the increase of RE content continuously increased both transverse and longitudinal impact toughness until excessive RE addition.

Study on the Magnetic Induction Effect of Rare-Earth La Modified Amorphous Ribbons

Prepared rare-earth La modified amorphous ribbon by doping Rare-earth La in Fe78Si9B13amorphous alloy. Investigated rare-earth content and annealing temperature as well as their influence on the magnetic induction effect and its amplitude. The results show that, when magnetic field is less than 1356 A/m, with the increase of Rare-earth content,the magnetic induction effect first increased and then decreased, when the magnetic field strength greater than 1356 A/m, the Rare-earth content influence little on magnetic induction effect, changing amplitude of magnetic induction effect shows first increased and then decreased with increasing Rare-earth content.

Magnetic Induction Effect of Amorphous Ribbon Modified by Rare-Earth

Prepared rare-earth La modified amorphous ribbon by doping Rare-earth La in Fe78Si9B13 amorphous alloy. Investigated rare-earth content and temperature, as well as their influence on the magnetic induction effect and it’s amplitude. The results show that, when magnetic field is less than 1356 A / m, with the increase of Rare-earth content ,the magnetic induction effect first increased and then decreased, when the magnetic field strength greater than 1356 A / m, the Rare-earth content influence little on magnetic induction effect , changing amplitude of magnetic induction effect shows first increased and then decreased with increasing Rare-earth content; temperature influence little on the magnitude of magnetic induction effect.

Effect of Rare Earth Y<sub>2</sub>O<sub>3</sub> Content on Microstructure of Gradient Bioceramic Composite Coating Produced by Wide-Band Laser Cladding

In the present paper, bioceramic coating with gradient compositional design was prepared on surface of Ti alloy by using wide-band laser cladding. Effect of rare earth Y2O3 content on gradient bioceramic composite coating was studied. The experimental results indicated that adding rare earth can refine grain. Different contents of rare earth affect formation of HA andβ-TCP in bioceramic coating. With increase of rare earth content, HA andβ-TCP were synthesized. When content of rare earth ranged from 0.4% to 0.6%, the active extent of rare earth in synthesizing HA andβ-TCP got best, which indicated that “monosodium glutamate” effect of rare earth played a dominant role. However, when rare earth content was up to 0.8%, the active extent of rare earth in synthesizing HA and β-TCP conversely went down, which demonstrated that rare earth gradually lost its catalysis in manufacturing HA andβ-TCP.

Investigation of magnetic properties and phase evolution of NdxFebal.TiCB10.5 (x=9, 9.5, 10, and 11) melt spun ribbons

The magnetic properties and phase evolution of boron enriched NdxFebal.TiCB10.5 (x=9, 9.5, 10, and 11) melt spun ribbons have been investigated. For x=9, 9.5, and 10, the main phases in the ribbons are Nd2Fe14B, Fe3B, and a dilute α-Fe. For x=11, the Fe3B phase is suppressed and only Nd2Fe14B and α-Fe were detected. An increase of rare earth content, from x=9 to x=10, was found to improve not only the intrinsic coercivity (iHc) but also the remanence (Br). The improvement in Br may be ascribed to the grain refinement as evidenced by transmission electron microscopy. A Br=9.2 kG, Hci=12.1 kOe, and (BH)max=16.2 MGOe were obtained on Nd10Febal.TiCB10.5 alloy ribbons quenched at 20 m/s followed with a 675 °C annealing for 10 min. Meanwhile, with an increase in the annealing temperature, the coercivity of the above alloy ribbons could be reduced to 9.8 kOe without sacrificing its Br and (BH)max.