Effect Of Rare Earth Addition Research Articles

Effect of rare earth additions on magnetic properties of Fe 82Nb 2B 14RE 2 (RE = Y, Gd, Tb and Dy) amorphous alloys

In the present paper the influence of RE alloying additions (Y, Gd, Tb and Dy) on magnetic properties (Curie temperatures, low temperature magnetization, zero field cooling–field cooling curves, domain structure, room temperature magnetostriction and magnetic permeability) of amorphous alloys of type Fe 82Nb 2B 14RE 2 are carefully examined. It was shown that substituting of yttrium atoms by magnetic elements, i.e. Gd, Tb and Dy leads to (i) an increase of the Curie temperature of amorphous phase from 416 K (for Fe 82Nb 2B 14Y 2) to 450 K (for Fe 82Nb 2B 14Gd 2) and (ii) a decrease of magnetization in saturation (magnetic field 7 T) which can be explained by antiferromagnetic Fe–RE coupling resulting in a decrease of magnetic moment calculated per magnetic atom from 2.00 μ B for the Fe 82Nb 2B 14Y 2 alloy (Fe in amorphous phase) to 1.51 μ B for the Fe 82Nb 2B 14Tb 2 alloy. It was concluded that Tb and Dy alloying additions introduce a local magnetic anisotropy responsible for significant decrease of initial magnetic permeability (about 5 times in relation to Fe 82Nb 2B 14Y 2 or Fe 82Nb 2B 14Gd 2 alloy), increase of magnetic irreversibility effect measured at 2 K (about 10 times in relation to the same alloys) and appearing of the finger-print magnetic domain regions (not observed for the Fe 82Nb 2B 14Y 2 and Fe 82Nb 2B 14Gd 2 alloys).

Effect of rare earth addition on Cu-Fe/AC adsorbents for phosphine adsorption from yellow phosphorous tail gas

Phosphine (PH 3) is a highly toxic air pollutant, commonly produced in phosphorous chemical industry. But it has received less research attention due to its handling difficultly. CO is the main content of the phosphorous chemical industry tail gas, the concentration of which is always more than 80 vol.%, and it can be the feed gas to produce various valuable products such as formate, oxalate, and methanol and so on. But, PH 3 is one of the important barriers, which is harmful to the following chemical process. In order to make use of the tail gas, PH 3 should be removed firstly, and CO should be covered in the whole purified procedure at the same time. In this work, the modified activated carbon (MAC) was used as the adsorbent to separate PH 3 from the mixture tail gas. Series of MAC adsorbents were prepared for the adsorption of PH 3, which loaded Cu-Fe and Ce (La), or separately. The PH 3 adsorption capacities, chemical and physical properties of MAC were all investigated. The results showed that over 99% PH 3 adsorption efficiency was achieved when used MAC adsorbents. The removal efficiency and PH 3 adsorption capacity of the Cu-Fe-Ce/AC (20:1:0.4) were both much higher than those modified activated carbons. The maximum PH 3 adsorption capacity was 71 mg of PH 3/g of MAC on the Cu-Fe-Ce/AC, which were much higher than literature data using CuO only for adsorbing hydride gases.

Effect of rare earth addition on structure and properties of Ni-P coating on SiCp/Al composites

The aim of this work was to improve the properties of Ni-P coating on SiCp/Al composites. The effect of rare earths addition on Ni-P coating structure was investigated by means of scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD) and electrochemistry methods. The results showed that as Y or La concentration was 0.15 g/L in plating solution, the highest value of deposition rate of Ni-P coating was found. And the structure of the obtained coating was modified to part of crystalline state from single amorphous Ni, such as Ni 3Y or Ni 3La, Ni 5Y or Ni 5La, Ni 2P 2Y or Ni 2P 2La. The properties of the Ni-P-RE alloy coating were improved greatly, for example, crystalline size became fine and compact, the free corrosion potential of the coating enhanced remarkably. Y had a better effect on the properties of the coating compared with La.

Effect of Rare Earth Addition on Electrical Properties of Zirconia Based Ceramics

Applications of stabilized zirconia include uses related to its low thermal conductivity, strength and electrical properties. Rare earth oxides (REO) were used as additives to stabilize appropriate crystalline phases at zirconia compacts. In this work zirconia based solid electrolytes were sintered with 10, 15 and 20 wt % of REO as sintering aids. Samples were prepared by uniaxial cold press and sintered at 1400 °C, followed by electric properties determination via impedance spectroscopy. Complimentary characterization was made by X-Ray diffractometry and quantitative phase analysis by Rietveld refinement. The ionic conductivity is affected by the amount of REO additive and this effect is correlated to the existing tetragonal and cubic phases for each composition

Influence of Rare-Earth Substitution for Iron in FeCrMoCB Bulk Metallic Glasses

The effects of rare earth addition on the glass forming ability of Fe50–xCr15Mo14C15B6Mx (x = 0, 2 and M = Y, Gd) bulks and ribbons are studied. The thermal and structural properties of the samples are measured by a combination of differential scanning calorimetry (DSC), x-ray diffraction and scanning electron microscopy. Chemical compositions are checked by energy dispersive spectroscopy analysis. The copper mold casting technique leads to a fully amorphous structure up to 2mm only for compositions containing Y or Gd. In the case of ribbons, a fully amorphous phase is observed for all the compositions. The roles of Y and Gd are discussed on the basis of melting behavior analyzed by high-temperature DSC. Such elements act as oxygen scavengers, avoiding heterogeneous nucleation.

Effect of rare earth additions on microstructure and mechanical properties of AZ91 magnesium alloys

In order to meet the demands of high temperature components in automobile, the microstructure and mechanical properties of several new die-casting AZ91-rare earth (RE) magnesium alloys were studied. The alloys were characterized by optical microscopy (OM), scan electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), tensile and creep tests. The results show that Ce addition has little effect on the mechanical properties of AZ91 alloy at high temperature, while Y and Nd addition play important role in the improvement of creep resistance. New alloys containing Y or Nd with excellent high temperature performance are selected to produce cylinder head cover of high power diesel engine of Red Flag car and oil pan of Besturn car. The new magnesium alloys with RE addition for die-casting have potential to produce power-train parts, and can greatly decrease weight.

The effect of rare earth additions on the electrochemical properties of Mg–5Al-based alloys

The corrosion properties of four Mg–5Al-based alloys with rare earth alloying elements (calcium, misch-metal and strontium) in a 0.01 M alkaline NaCl solution were examined using electrochemical tests and surface analyses. The electrochemical tests indicated that the addition of 1% rare earth improved the pitting potential, film formation and charge transfer resistance of the Mg–5Al specimens. Moreover, the addition of 1Sr produced the best corrosion resistance due to the continuous precipitation of Mg/Al-rare earth compounds as a corrosion barrier.

Effect of Rare Earth Addition in Plasma Nitriding on Microstructure of Chromium Electro-Plating

As an active metal, chromium is easy to form oxides film on the surface, which acts as an obstacle to the nitrogen diffusion in plasma nitriding. Rare earth (RE) was introduced into the conventional plasma nitriding (CPN) to improve the nitriding behavior. Chromium coatings were treated by CPN and rare earth plasma nitriding (REPN) at 620°C for 5 and 10 hours respectively. Comparative study showed that the addition of RE prompted greatly the formation of higher nitrogen containing phase CrN, rather than Cr2N. It created a crack-free, much denser and thicker nitrides layer, which contributed to the increase of hardness. The dynamic ultra micro hardness of the samples treated by REPN was nearly 1600GPa, which was much higher than the original and the CPN treated samples. The conclusion could be drawn that compared to CPN, REPN are more efficient for chromium coating nitriding.

Effect of rare earth additions on microstructure and texture development of magnesium alloy sheets

Rare earth elements or yttrium can weaken the strong basal textures of magnesium sheets and are of interest for the improvement of sheet formability. The weakening of magnesium sheet textures with increasing content of Ce, Nd and Y is connected to the solid solubility of the respective element. A relationship is drawn between the weak textures and the appearance of deformation bands with compression and double twins during rolling and a grain growth restriction during annealing of the sheets.

The effect of different rare earth elements content on microstructure, mechanical and wear behavior of Mg–Al–Zn alloy

The effect of Rare earths addition to AZ91 magnesium alloy and its influence on the microstructure and mechanical properties was investigated in this study. Addition of cerium rich misch metal to AZ91 alloy resulted in formation of needle shape particles, which had a very high thermal stability, providing superior mechanical properties compared to AZ91 magnesium alloy. As a result, the grain boundaries were less susceptible for grain boundary sliding at high temperatures. The steady state creep rates were specified and for the AZ91 alloy and the results indicate a mixed mode of creep behavior, with some grain boundary effects contributing to the overall behavior. However for the RE added samples, sliding of grain boundaries was greatly suppressed and the dislocation climb controlled creep was the dominant deformation mechanism. Dry sliding wear tests were also performed to investigate the effect of Rare Earth additives on wear response of AZ91 magnesium alloy. Weight loss values were determined and wear mechanisms of the alloys with different amount of REs were investigated. Abrasion, delamination and gross plastic deformation were identified as prevailing wear mechanisms. Abrasive wear that activated at lower loads and sliding speeds increased wear rates for less ductile specimens of Rare Earth enriched. However AZ91 alloy containing Rare Earth contents show superior resistance to gross plastic deformation which operated at more severe wear conditions. This is due to existence of Al 11RE 3 phase that posses attractive mechanical properties at elevated temperatures.

Microstructure and properties of 17-4PH steel plasma nitrocarburized with a carrier gas containing rare earth elements

The effect of rare earth addition in the carrier gas on plasma nitrocarburizing of 17-4PH steel was studied. The microstructure and crystallographically of the phases in the surface layer as well as surface morphology of the nitrocarburized specimens were characterized by optical microscope, X-ray diffraction and scanning tunneling microscope, respectively. The hardness of the surface layer was measured by using a Vickers hardness test. The results show that the incorporation of rare earth elements in the carrier gas can increase the nitrocarburized layer thickness up to 55%, change the phase proportion in the nitrocarburized layer, refine the nitrides in surface layer, and increase the layer hardness above 100HV. The higher surface hardening effect after rare earth addition is caused by improvement in microstructure and change in the phase proportion of the nitrocarburized layer.

Effect of rare earth addition on microstructural, mechanical and electrical characteristics of Cu-6%Fe microcomposites

Cu-6%Fe (mass fraction) microcomposites containing (0–0.30)% rare earth elements were prepared by cold drawing and intermediate heat treatments. Microstructure was observed, and mechanical properties and electrical conductivity were measured for alloys at various drawing strain levels. Adding rare earth elements could reduce the size of primary Fe and Cu dendrites of Cu-6%Fe. Ultimate tensile strength increased but electrical conductivity decreased with the increase of drawing strain. Rare earth additions in Cu-6%Fe slightly increased the strength at low strain and effectively improved the conductivity at high strain. Both strain hardening rate and conductivity loss of Cu-6%Fe containing rare earths were reduced at lower strain than Cu-6%Fe.

Effects of rare-earth additions on the microstructure and strength of Cu–Ag composites

The filamentary composites of Cu–6 wt.% Ag and Cu–12 wt.% Ag containing rare-earth elements with different contents were prepared by casting and cold drawing. The microstructure was observed and the tensile strength determined for the composites at different draw ratios. The rare-earth elements of 0.05–0.15 wt.% in Cu–6 wt.% Ag and 0.1–0.3 wt.% in Cu–12 wt.% Ag result in large spacing or low density of the filamentary interface in the composites. Some hard compound particles exist in the composites containing rare-earth elements and result in high stress concentration. The rare-earth additions in the composites can improve the strength at low drawing degrees but reduce the strength at high drawing degrees.

Effects of Rare-Earth Addition on Properties and Microstructure of Lead-Free Solder Balls

In the present work, lead-free solder balls were manufactured by a uniform droplet spray (UDS) method. The solder used to produce solder balls was based on the Sn-3.8Ag-0.7Cu alloy. Different amounts of cerium-based mixed rare-earth (RE) elements were added into the Sn-3.8Ag-0.7Cu solder alloy in order to examine the effects of small amounts of RE additions on the physical properties, microstructure, and surface smoothness of the solder balls. Results show that a small amount of RE addition has no obvious effect on the melting temperature, but it decreases the nucleation undercooling degree. Moreover, a small amount of RE addition (<0.25 wt.%) can improve the surface smoothness of the solder balls. However, when the RE was added up to 0.5 wt.%, the surface smoothness of the solder balls was deteriorated. From observations of the microstructure of the solder balls, it is obvious that the RE addition affects solidification behavior, and as a result, the surface smoothness of the solder balls.

Effect of rare earth addition on shear strength of SnAgCu lead-free solder joints

In the present study, the effect of adding trace amount of rare earth (RE) on the shear strength of Sn3.8Ag0.7Cu lead-free solder joints has been investigated. The shear strength of the solder joints as-reflowed and after aging at 150 °C for 168 and 336 h was measured at a constant loading rate of 0.3 mm/min and room temperature. The investigation indicates that the shear strength of Sn3.8Ag0.7Cu0.1RE solder joints is lower than that of Sn3.8Ag0.7Cu solder joints. The shear strength of both Sn3.8Ag0.7Cu solder joints and Sn3.8Ag0.7CuRE solder joints was reduced after aging at elevated temperature. However, the shear strength reduction rate of the Sn3.8Ag0.7Cu solder joints was much faster than that of Sn3.8Ag0.7CuRE solder joints. Moreover, the fracture surfaces were examined by scanning electron microscopy (SEM) and the thickness of intermetallic compounds layer (IML) in the solder joints that join Cu substrate was measured. The results indicated that the addition of rare earth elements suppresses the growth of the thickness of intermetallic compounds layer.

Effect of rare earth (RE) elements on V-based hydrogen storage alloys

In this work, the effect of RE additives on the properties of V 55 Ti 22.5 Cr 16.1 Fe 6.4 alloy ( RE = La , Pr, Ce and Nd, separately) was discussed. It was demonstrated that RE additives improve the activation property rather than kinetics during cycling, absorption capacity and the plateau pressure. Two phases, including BCC main phase and Ce second one, were found in Ce-containing alloy. It is inferred that RE element offers a route for hydrogen to enter the alloys more easily, which leads to the improvement of activation property of the alloys.

The Effects of Rare Earth Elements on Corrosion Resistance of Sol-Gel Coatings for 2024 Aluminum Alloy

Rare-earth modified coatings on 2024 aluminum alloy were prepared by sol-gel methods, aiming at improving the corrosion resistance with the environmental friendly features. The investigation put emphases on the effects of rare-earth additives on corrosion resistance and microstructure of sol-gel coatings. The results revealed that coated samples containing 2g·L-1 rare-earth not only delayed the incubation period of corrosion, but also hindered the development of it, and their corrosion rate decreased 80.3% compared with the bare ones and was 15.9% than the rare-earth free coated ones. The action of rare-earth on morphology and microstructure of sol-gel coatings for 2024 Al alloy was studied by SEM. High density good cohesion, and intact coverage were showed clearly ,which provided a reliable proof of the reformative effects of rare-earth additives.

On the advantages of using powder metallurgy in new light metal alloy design

Historically, the production of metallic components for the automotive and aerospace industries has been dominated by wrought and ingot metallurgy metal forming practices. These technologies offer considerable design flexibility to engineers and are readily amenable to ferrous and nonferrous alloys alike. However, in applications that require precise dimensional control, the tolerances attainable are generally inadequate. This represents a formidable limitation and mandates the incorporation of expensive secondary machining. Furthermore, because these processes are carried out under conditions that approach those of equilibrium, these technologies are also faced with rather strict limitations on the range of alloy chemistries that can be employed. As the demands for improved material performance and process economics increase, the aforementioned shortcomings become increasingly important. Consequently, considerable attention has and continues to be focused on alternate metal forming techniques such as powder metallurgy (P/M). Using the P/M approach, dimensional tolerances are commonly improved by one to two orders of magnitude and alloy chemistry limitations are essentially eliminated. The work described herein provides an overview of select P/M techniques developed by the authors, initially to enhance the hardness and tensile properties of aluminum-based P/M alloys through a mineral dissociation/diffusion process. This is expanded through alloy development research wherein a P/M processing route designed to simulate industrial practices is used in the most recent work based on the effects of rare earth additions on selected mechanical properties of aluminum P/M alloys. These results include a compilation of theoretical calculations (thermodynamics and diffusion rates) that are supported by experimental data using techniques that include electron microprobe analyses, X-ray diffraction, tensile testing, and wear testing. Specific findings are that minerals/compounds such as wollastonite and silver nitrate can be successfully reacted to enhance selected mechanical properties of aluminum P/M alloys and that wear resistance may be improved through a P/M approach applied to AA2014.

Environmentally friendly solders 3–4 beyond Pb-based systems

Based on environmental considerations, global economic pressures, enacted by legislations in several countries, have warranted the elimination of lead from solders used in electronic applications. Sn3.5Ag, SnAgCu, and Sn0.7Cu have emerged among various lead-free candidates as the most promising solder alloys to be utilized in microelectronic industries. However, with the vast development and miniaturization of modern electronic packaging, new requirements such as superior service capabilities have been posed on lead-free solders. In order to improve the comprehensive property of the solder alloys, two possible approaches were adopted in the current research and new materials developed were patented. One approach was involved with the addition of alloying elements to make new ternary or quaternary solder alloys. Proper addition of rare earth element such as La and Ce have rendered solder alloys with improved mechanical properties, especially creep rupture lives of their joints. Another approach, the composite approach, was developed mainly to improve the service temperature capability of the solder alloys. Composite solders fabricated by mechanically incorporating various reinforcement particles to the solder paste have again exhibited enhanced properties without altering the existing processing characteristics. The recent progress and research efforts carried out on lead-free solder materials in Beijing University of Technology were reported. The effects of rare earth addition on the microstructure, processing properties, and mechanical properties were presented. The behaviors of various Sn-3.5Ag based composite solders were also explicated in terms of the roles of reinforcement particles on intermetallic growth, steady-state creep rate, the onset of tertiary creep, as well as the overall creep deformation in the solder joints. Thermomechanical fatigue (TMF) behavior of the solder alloys and composite solders were investigated with different parameters such as ramp rate, dwell time, etc. The damage accumulation features and residual mechanical properties of the thermomechanically-fatigued composite solder joints were compared with non-composite solder joints. To match the lead-free alloys, various types of water soluble no-clean soldering flux have also been developed and their properties were presented.

Rare earth microalloying in as-cast and homogenized alloys Cu–6 wt.% Ag and Cu–24 wt.% Ag

Alloys Cu–6 wt.% Ag and Cu–24 wt.% Ag were prepared by casting and homogenization treatment. The effect of rare earth additions on the as-cast and homogenized microstructure was investigated by adding 0.1 wt.% rare earth elements into both the alloys. Adding rare earth elements results in higher eutectic proportion in both alloys, finer primary α grains in the Cu–6 wt.% Ag and more disperse α plates in the eutectic structure of the Cu–24 wt.% Ag. Homogenization treatment produces secondary Ag-rich particles in the α matrix in both alloys and the secondary precipitates in the alloy with high Ag content have higher proportion and more distinct morphology than in the alloy with low Ag content. Adding rare earth elements can result in finer and more uniform secondary precipitates in both the homogenized alloys. The Ag concentration in the eutectic structure in all alloys significantly increases after homogenization treatment and the homogenized alloys containing rare earth elements have higher Ag concentration in the eutectic structure than those non-containing rare earth elements.