Effects Of Rare Earth Elements Research Articles

Effects of Rare Earth Elements on Microstructure and Corrosion Resistance of Low Alloy Steel Based on Ultra-Thin Cast Strip Process

This laboratory study aimed to reveal the inner connects between the microstructure and corrosion properties of a RE microalloyed ultra-thin cast strip (UCS) steel. The microstructure mainly consisted of homogeneous polygonal ferrite (PF) with a small amount of pearlite (P), while adding multiple alloying elements led to the appearance of granular bainite (GB) and bainitic ferrite (BF). RE elements strongly promoted the homogenization and refinement of microstructure by segregating towards the solid–liquid interface. Potentiodynamic polarization, EIS, and weight loss curves under wet–dry immersion test confirmed that the corrosion behavior was significantly improved by RE, while the addition of RE had no obvious change on tensile strength. The corrosion resistance of the homogeneous single-phase microstructure was proved to be better than that of multiphase microstructure. Hence, RE had a remarkable influence on improving corrosion resistance when the experimental steels processed single-phase microstructures.

The effects of microstructural parameters on the tension-compression mechanical behavior of extruded Mg-XY rods using crystal plasticity finite element modeling

In the present study, the effects of rare earth element Y, texture intensity, and grain size on the tension-compression mechanical behavior of extruded Mg-XY(X = 0–3, wt pct) rods were investigated using improved phenomenological crystal plasticity. To this end, finite element modeling of a three-dimensional representative volume element (3D-RVE) was employed to consider the effects of microstructural parameters. Subsequently, the computational modeling approach was validated with the experimental data to assess the reliability of predictions of the responses of a polycrystalline aggregate. Afterward, the validated computational modeling was employed to predict the mechanical behaviors of extruded Mg-XY (X = 0–3, wt pct) by considering the role of slip/twinning activities during deformation. The results showed that the Y addition significantly improved the yield strength, ultimate strength, and ductility. Examination of the deformation modes activities indicated that the basal slip activity of extruded Mg-XY (X = 1–3, wt pct) is higher than that of extruded pure Mg due to the formation of non-basal texture components, which hindered the twinning activation. Increasing the Y content further reduced the suppression of tensile twinning activity. Therefore, the weak tension–compression yield asymmetry of extruded Mg-XY (X = 1–3, wt pct) was mainly attributed to the reduced tensile twinning activity. The simulated stress-strain curves illustrated that texture weakening, and grain refining improved the mechanical behavior and reduced tension-compression yield asymmetry.

Effect of rare earth elements on microstructure and mechanical properties of bainite/martensite bearing steel

This study aims to investigate the effect of rare earth (RE) elements on the microstructure and mechanical properties of bainite/martensite (B/M) bearing steel. For this purpose, GCr15 bearing steels with different RE contents were prepared and analyzed after experiencing B/M heat treatment. The results show that RE addition significantly delays the bainite transformation by reducing grain boundary energy and carbon diffusion rate, leading to a reduction of bainite volume fraction from 27.3% for bearing steel without RE addition to less than 14.5% for RE-treated steels, and the corresponding increase of martensite volume fraction from 39.1% to more than 50.2%. The volume fraction of retained austenite (RA) remains nearly unchanged. Meanwhile, the width of the bainite needles gets refined in RE-treated steels while martensite and RA blocks become bigger. Compared with bearing steel without RE addition, larger RA blocks in RE-treated steels unexpectedly have higher stability due to higher dislocation density and surrounding phases strength. Accompanied by the change of microstructure, the hardness in RE-Treated steels improves slightly, while the fracture toughness dramatically deteriorates which can be directly explained by two mechanical phenomena during toughness test. The one is that the RA in RE-treated steels is harder to transform into martensite and thus consumes less energy; The other one gives that cracks tend to propagate along grain boundaries or martensite interfaces with less energy consumption easily in RE-treated steels instead of breaking off bainite.

Facilitating enhanced microwave absorption properties of barium hexaferrite/polyaniline composites based on tunable interfacial polarization by rare earth doping

Barium hexaferrite (BaM)/polyaniline (PANI) is a typical microwave absorbing composite that effectively integrates magnetic and electric losses. To enhance its microwave absorption properties, a facile method based on rare earth element doping was explored; the effects of rare earth elements on the microstructures and properties of both BaM nanopowders and the subsequent BaM/PANI composites were investigated. The use of rare earth elements, including La, Nd, and Ce, in the BaM particles alleviated the constraints of the electric polarization in PANI near the surfaces of the BaM particles; this resulted in more electric polarization at the interfaces of the Re-BaM and PANI phases. This provided a versatile way to enhance the absorption efficiency, expand the absorption frequency range, and reduce the thickness. The La-BaM/PANI composite demonstrated a maximum reflection loss of approximately − 63.6 dB at 7.76 GHz with an optimum thickness of 3.28 mm. The effective absorption range of the Nd-BaM/PANI composite was 4.72 GHz. Ce-BaM/PANI composites released a relatively broad effective frequency range of approximately 3.88 GHz and a small thickness of 1.58 mm.

Effect of Rare Earth Elements on Microstructure and Hot Workability of AISI T15 High Speed Steel

Effect of Rare Earth Elements on Microstructure and Hot Workability of AISI T15 High Speed Steel

Uncovering the effects of Ce and superheat temperature on Fe-rich intermetallic and microporosity formation in aluminum alloy

The continuous accumulation of Fe impurities in recycled aluminum is a major obstacle for its wide application in fatigue sensitive parts due to the formation of Fe intermetallics and micropores. In this paper, we study the effects of rare earth elements and superheat temperature on the crystal structure of Fe-rich intermetallic and morphology of microporosity using micron-resolution phase-contrast lens magnification based X-ray computed tomography (XCT). Using image registration and U-net convolutional neural networks (CNN) algorithm, we first segmented the morphology of Fe-rich intermetallic and quantified their distribution as a function of Ce additions and superheating temperature. It was found that the addition of Ce elements promoted the microstructure refinement and restricted the growth of β-Fe intermetallics effectively. Lowering the superheat temperature from 780 °C to 680 °C does not show a linear relationship between porosity level and the reduction of the intermetallic volume fraction. In fact, we have found the size of eutectic Si and Fe-rich intermetallic is the smallest at 730 °C and the tensile strength at as-cast condition with a superheating at 730 °C and Ce addition can give the greatest elongation at 4.26%, and yield and tensile strengths at 175.3and 249.5 MPa, respectively. • Rare earth Ce refines microstructure of Al-Si-Mg alloys and thus reduces pore size. • Non-linear relationship between superheat and pore size were found. • 3D Segmentation of α-Fe and β-Fe intermetallics using U-net CNN algorithm were developed for CT data. • Minimizing negative impacts of Fe-intermetallics and pores on properties is achieved.

Evaluate the effects of rare earth elements on sweet pepper seeds germination process, seedlings growth and plants productivity

This experiment was conducted to investigate the response of pepper seeds germination process and vegetative growth traits in seedlings stages as well as plant growth and productivity of open field to rare earth elements (REEs) i.e., cerium nitrate, neodymium nitrate, and praseodymium nitrate at concentrations of 0.0, 0.5, 1.0, and 1.5 ppm. Among the various REEs treatments, cerium nitrate at 0.5, 1.0, and 1.5 ppm were more significantly effective than others in increasing most of the seedling parameters and 1.5 ppm cerium nitrate exhibited the maximum effect in germination characteristics with no significant differences among 0.5, 1.0 and 1.5 ppm cerium nitrate as well as 1.5 ppm neodymium in all germination parameters in both seasons. The superiority of vegetative growth, fruit physical and total yield as well as fruit chemical content (ascorbic acid and carbohydrates) were obtained with neodymium followed by praseodymium foliar spray applications with compared to cerium or control treatments. The foliar spray treatment of 1.5 ppm neodymium nitrate exhibited an increment up to 54.1, 23.7, 29.5, and 33.1% over that observed in the control of average fruit weight, fruit diameter, fruit length, and total yield, respectively.

Evaluate the effects of rare earth elements on sweet pepper seeds germination process, seedlings growth and plants productivity

Evaluate the effects of rare earth elements on sweet pepper seeds germination process, seedlings growth and plants productivity

Prediction of mechanical properties of Mg-rare earth alloys by machine learning

In this work, the quantitative relationship among the composition, processing history and mechanical properties of Magnesium-rare earth alloys was established by machine learning (ML). Based on support vector regression (SVR) algorithm, ML models were established with inputs of 310 sets of data, which can predict ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) with well accuracy. In order to verify the general applicability of our model, new data were collected from the literature, and the ML models was used to predict their mechanical properties respectively. The MAPE of UTS, YS and EL predicted by SVR model are 9%, 12% and 36%, respectively. The reasons for the deviation of the predicted results were also analyzed. The effects of rare earth elements on UTS, YS and EL were analyzed by the SVR models. The established ML model was used to recommend the composition and processing history of new Magnesium-rare earth alloys with high mechanical properties.

Effects of rare-earth elements on twinning deformation of Al alloys from first-principles calculations

Effects of rare-earth (RE = Ce, Dy, Er, Ho, La, Tb, and Yb) elements on twinning deformation of Al alloys are studied using first-principles calculations. The influence rules of RE atoms doped at the first nearest neighbor layer on the generalized planar-fault energy curves are analyzed, and the interaction energies of RE atoms in various atomic layers of stacking fault configurations are studied. On the basis of the improved twinning criterion formula and uniform distribution model, the influence rules of RE solute concentration on twinnability at the crack tip, at the grain boundary, and inside the grain of Al alloys are further analyzed. Results show that RE elements can evidently decrease the minimum energy barriers of dislocation nucleation and motion, and La and Ce atoms have significant effects on promoting dislocation nucleation and motion. Ce and La atoms can promote twinning deformation at the crack tip. Except for the La atom, the remaining RE atoms inhibit twinning deformation at the grain boundaries, and La atom at high concentrations is beneficial to promote twinning deformation at the grain boundaries. RE atoms (Dy, Er, Ho, La, Tb, and Yb) for twinning deformation inside Al alloy grains exhibit slight effect. Nevertheless, the Ce atom can greatly promote twinning deformation inside the grains when the solute concentration is in the range of 5%–7.1%, and the twinning ability decreases with the increase in solute concentration again. This work takes the lead in revealing the mechanism of twinning deformation by considering the interactions between RE atoms and generalized faults, which provides valuable guidance for exploiting high-performance Al–RE alloys.

Effects of RE (Nd, Ce, Y, La) on TiC(100)/Fe(110) interface based on first-principles calculations

The effects of rare earth elements (Nd, Ce, Y, La) on the bonding strength and stability of the TiC(100)/Fe(110) interface were studied based on first-principles calculations. The calculation of the surface energy of the low-index surface of the bulk phase shows that the TiC(100) and Fe(110) sections are the two sections with the lowest surface energy in the two bulk phases, respectively. The calculation of the interface shows that in the five interface models, the formed interface can exist stably, but the bonding strength is not high, and the interface is the weak point of TiC/Fe matrix composites. The calculation of the rare earth doped interface shows that when Fe atoms are substituted, γ-Ce (−5.30454 J/m2), γ-Y (−5.28015 J/m2), γ-La (−5.22953 J/m2), γ-Nd (−5.22545 J/m2); when Ti atoms are substituted, γ-Ce (−4.00834 J/m2), γ-Y (−4.03247 J/m2), γ-La (−3.96345 J/m2), γ-Nd (−3.91418 J/m2). The addition of the four rare earth elements can reduce the interfacial energy of the interface and increase the stability of the interface, thereby increasing the properties (hardness, wear resistance, strength, etc.) of TiC/Fe matrix composites. When the Ce element-doped interface replaces Fe atoms, the enhancement effect on the interface is stronger.

Effect of rare earth element on amorphization and deformation behavior of crystalline/amorphous dual-phase Mg alloys

The crystalline/amorphous (C/A) dual-phase structure is a new design strategy to improve the mechanical properties of Mg alloys. Here, the effect of the content of rare-earth element Y on the deformation mechanism and mechanical behavior of the C/A Mg/(MgCu)100-xYx dual-phase Mg alloys under tensile loading is investigated by molecular dynamics simulation. The results show for the first time that the amorphous phase thickness of the alloys increases obviously after relaxation, which is mainly due to the existence of element Y in amorphous phase. And with the increase of the content of element Y, the thickness of amorphous phase increases. The results indicate that the diffusion of element Y from amorphous phase to amorphous-crystalline interface (ACI) promotes the migration of ACI towards crystalline phase (i.e., the amorphization of crystalline phase). The results further pointed out that the amorphization of Mg alloys depends on two factors: one is that the amorphous phase contains a certain concentration of element Y, and the other is the existence of ACI. The results show that there is a critical amorphous phase thickness of the dual-phase Mg alloys, that is, the critical content of Y element, which can make it achieve nearly perfect plasticity.

Effect of rare earth elements on magnetic properties of non-oriented electrical steels

The effect of rare earth elements (REMs) on the magnetic properties of non-oriented electrical steels was studied using industrial trials. The variation of the magnetic properties was discussed in terms of the effect of inclusions, precipitates, grain size, and textures in the steel with and without REMs. Inclusions of MgO·Al2O3-CaS and (Mg, Mn, Ca)S in REMs-free steel were modified into composite ones of MgO·Al2O3-LaAlO3, La2O2S-MgO and (La, Ca)S in the steel with 0.0006% lanthanum, and to (La, Ce)2O2S-CaS-MgO, (Ce, La)S in the steel with 0.0007% lanthanum and 0.0015% cerium. The number density of fine MnS was remarkably decreased by the addition of REMs, leading to an increase in the average grain size. The steel containing 0.0006 wt% lanthanum possessed the best combination of core loss and magnetic induction due to the decrease of micro-sized inclusions and fine MnS, the increase of grain size, and the optimization of recrystallization textures. For the steel with excess REMs addition, the large number density of rare earth sulfides with the size of approximately 1 μm tended to deteriorate the grain size and textures.

Enhanced mechanical properties of as-cast rare earth bearing magnesium alloy via elevated-temperature homogenization

The effects of elevated-temperature homogenization on the microstructure and mechanical properties of a magnesium alloy containing mischmetal rare earth (RE) were investigated. It was revealed that the homogenization treatment leads to spheroidization and partial dissolution of the Mg12RE phase in the eutectic constituent. For the optimum homogenized alloy (20 h at 535 ºC), the elimination of the deleterious eutectics and the solid solution strengthening effect of RE elements were the main contributing factors for improving the ultimate tensile strength and ductility. Accordingly, a 157 % increase in tensile toughness compared to the as-cast condition was recorded. Moreover, as a direct consequence of eliminating the eutectic constituent, homogenization led to a change in the fracture mechanism from a brittle intergranular mode to an intragranular cleavage with the incorporation of some ductile dimples. Accordingly, homogenization heat treatment was found to be an alternative enhancing route of strength-ductility trade off, besides thermomechanical processing (by hot deformation and dynamic recrystallization) and severe plastic deformation.

The effect of rare earth element doping on thermoelectric properties of GeTe

GeTe has attracted extensive attention due to high thermoelectric performance. Herein, we comprehensively investigate the effect of rare earth element (Eu, Gd, Er and Tm) substitutions at Ge site of GeTe on its thermoelectric performance. It is found that the substitution limit of Eu, Gd, Er and Tm at Ge site of GeTe increases from 0.8 to 1.8 mol.% with increasing atomic number. The local magnetic moment arising from the substituted rare earth element enhances the Seebeck coefficient and in turn results in enhanced power factor at the entire measurement temperature range (from 303 to 723 K). Additionally, the increasing substitution limit with increasing atomic number of rare earth element strengthens the mass and strain-field fluctuations, which contributes to strengthened phonon scattering, and leads to reduced lattice thermal conductivity. The simultaneously enhanced power factor and reduced lattice thermal conductivity enhances the dimensionless figure of merit at the entire measurement temperature range, and correspondingly enhances the average dimensionless figure of merit from 0.38 of GeTe to 0.63 of Ge0.98Er0.02Te. This work indicates rare earth element can be used an effective dopant in GeTe to improve the thermoelectric properties.

Synergistic effects of solutes on active deformation modes, grain boundary segregation and texture evolution in Mg-Gd-Zn alloys

Synergistic effects of rare earth elements (RE) and Zn have a major impact on the properties of ternary Mg-RE-Zn alloys. This study illuminates their dependence on the solute ratio by comparing texture evolution, solute segregation, and active deformation modes of three Mg-Gd-Zn alloys with a varying Gd:Zn ratio of 2:1, 1:1 and 1:2. A low Gd:Zn ratio led to a texture featuring a pronounced TD-tilted basal pole spread alongside a magnified solute segregation at grain boundaries, indicating a significant impact of solute-boundary interactions on RE-texture formation. Atom probe tomography revealed major alterations of the segregation energy of both Gd and Zn, depending mainly on the solute ratio rather than the absolute solute concentration. Additionally, the alloy with the smallest Gd:Zn ratio, i.e. Gd:Zn = 1:2, showed the highest direction dependent anisotropy of the yield stress under tensile strain, which was attributed to a magnified anisotropy of twinning depending on the Gd:Zn ratio. EBSD assisted slip trace analysis showed that the occurrence of non-basal slip systems could be increased by reducing the Gd:Zn ratio. Synergistic solute effects were found to be crucial for the activation of non-basal slip, solute segregation, as well as the formation of RE-texture components and proven to be highly sensitive to the solute ratio.

Effect of rare earth elements on the segregation behavior and microstructure of super austenitic stainless steel

Super austenitic stainless steel (SASS) was prepared by non-consumable vacuum arc melting for the first time. The effects of rare earth (RE) elements on its solidification microstructure and segregation behavior were investigated. The σ phase is the main precipitation phase in SASS. The addition of RE elements can refine the solidification microstructure and the dendrite spacing. The addition of RE elements reduced the secondary dendrite spacing at top (S1) by 5.22 μm. The elements as Cr, Mn, and Mo have positive segregation, and elements as Ni and Fe have negative segregation. The addition of RE elements has the trend of reducing element segregation, thereby inhibiting the σ phase precipitation. And the addition of RE reduces the hardness of the secondary phase.

The effect of rare-earth element (Gd, Nd, La) doping of NiO films on UV photodetector

The semiconductor-based UV photodetectors are the most essential devices in the field of space observations, military, DNA sequencing, analysis of protein, medical imaging, checking of atmospheric pollution, optical communications radiation, etc. With such a wide range of possible applications, the nanostructured pristine and rare-earth (RE) doped NiO ((NiO: Gd(1%), NiO:Nd(1%), NiO:La(1%)) thin films were prepared and investigated for their suitability as UV photodetectors. The films were prepared by nebulized spray pyrolysis (NSP) at a substrate temperature of 450 °C. The x-ray diffraction studies confirm the cubic single phase with the polycrystalline nature of the prepared films. The spectroscopic studies such as absorbance and photoluminescence confirm that increase in the optical bandgap and 391 nm PL emission is attributed to the near band edge emission of the NiO. The x-ray photoelectron spectroscopy reveals the presence of nickel and the doped elements with their oxidation states. The UV photodetector performance of the prepared NiO films was carried out under the irradiation of 365 nm light. The NiO:Gd exhibits the best responsivity (0.353 AW−1), external quantum efficiency (120%), detectivity (1.72 × 1010 Jones) and rise time (2.0 s), and fall time (2.2 s). Importantly, strategies such as limited doping (1 at.%) and larger ionic radii of Gd incorporation into the host NiO cause a moderate increase in the lattice distortion and inhibit the recombination rate instead of behaving as a recombination center. In addition, the conduction band (CB) electrons are trapped by a greater number of oxygen vacancies residing at the Gd3+ 4f state and cause a good separation of charge carriers. Overall, these modifications enhance the mean lifetime of electrons, consequently reducing the recombination rate and enhancing the photoresponse.

Effect of Rare Earth Elements on the Microstructural and Mechanical Properties of ZK60 Alloy after T5 Treatment

Effect of Rare Earth Elements on the Microstructural and Mechanical Properties of ZK60 Alloy after T5 Treatment

Effects of rare earth elements (REE) on terrestrial organisms: current status and future directions.

Rare Earth Elements (REE) are becoming increasingly important economically and highly exploited, thus contributing to REE increases in ecosystems. The ecotoxicological effects of REE on the terrestrial environment are, however, not fully understood and information on the biological effects of REE is urgently required for environmental risk assessments. In this review, studies and gaps in the existing scientific literature regarding the toxicological effects of REE on terrestrial organisms are presented. A total of 41 articles from the Web of Science database are discussed. La and Ce are the most studied elements, while little information is found concerning heavy REE. Most studies have been performed on plant species and few investigations are available for animals. Plant effects such as reduced mitotic index, germination and photosynthesis and antioxidant system enzyme alterations have been reported. Invertebrate effects include mortality, reproduction alterations and reduced locomotion. Based on the limited number of articles on terrestrial environment REE effects, this review highlights the need for more detailed studies in order to elucidate the effects associated with the REE hormesis and perform complete risk assessments with the establishment of safe REE usage limits.