Effect Of Ce Content Research Articles

Insight into the effect of Ce content on the magnetic properties of Ce-magnets with grain boundary diffusion Pr-Al alloys

The development of cost-effective Ce-magnets with high Ce content is urgent to realize the vision of cost reduction and performance enhancement. Dual-main-phase Ce-magnets with different Ce content (Ce accounted for the total amount of rare earths is 40%, 50% and 60%) are prepared. The Pr80Al20 (at%) alloy is selected as diffusion source for the three magnets using the grain boundary diffusion technique under the same conditions. The correlation of magnetic properties and microstructures before and after diffusion with different Ce contents are systematically analyzed. According to the EPMA results, the presence of Ce in the magnets facilitates the diffusion of Pr elements along the grain boundaries, which significantly increases the diffusion depth of Pr inside the magnets. As a consequence, the percentage increment of coercivity increase with the Ce content due to the increased diffusion depth. This study provides new insight into the preparation of dual-main-phase Ce-magnets with high Ce content of 40–60%.

Effect of Ce content on the microstructure and TiN precipitation behaviour of high-titanium steel during slow cooling solidification

ABSTRACT This study used high-temperature melting experiments, optical microscopy, and scanning electron microscopy to investigate the effects of various Ce contents (0 wt.%~0.0165 wt.%) on the microstructure and TiN precipitation behavior in high-titanium steel during slow cooling solidification. The findings show that the microstructure of the solidified steel in each experiment are equiaxed grains at a cooling rate of 0.17 ℃/s. TiN mainly precipitates in the Liquid + δ two-phase region in this experimental steel. CeAlO3 and Ce2O2S precipitate before TiN, and their small lattice misfit with TiN (7.55% and 7.90%, respectively) are the primary cause of their propensity to act as the cores of TiN heterogeneous nucleation. The TiN area density in each experimental steel increases from 38.6 no./mm2 → 61.4 no./mm2 → 89.3 no./mm2 → 105.8 no./mm2 when the Ce content in the steel rises from 0 wt.% → 0.0015 wt.% → 0.0058 wt.% → 0.0165 wt.%.

Structure and properties of cerium-doped TiO2 coatings on Ti40Nb alloy by micro-arc oxidation

Peri-implantitis and insufficient osseointegration are major challenges currently facing dental implants. Therefore, enhancing the antibacterial and bioactive properties of implants is crucial. This study developed a novel Ce-doped porous coating on low-modulus Ti40Nb alloy by micro-arc oxidation to improve antibacterial and bioactive properties. We systematically investigated the microstructure, phase composition, adhesion to the substrate, hydrophilicity, antibacterial and cell compatibility of the coatings, and the effect of Ce content on the coating formation was discussed. The increase in the concentration of Ce3+ ions in the coating significantly enhances its antibacterial properties. The introduction of the porous structure endows the coating with excellent osteogenic differentiation activity, indicating that the cerium-doped MAO coating on the Ti40Nb alloy has great potential in dental applications.

Correlation between Ce content and Tb–Cu grain boundary diffusion efficiency in Ce-containing Nd–Fe–B magnets

Ce-containing Nd–Fe–B magnets have been widely used because of their low cost, but the effects of Ce content in the magnets on the grain boundary diffusion (GBD) behavior are still unclear.

Effect of Ce content on precipitation behavior in S31254 super austenitic stainless steel

The precipitation of Cr- and Mo-rich σ phases will seriously deteriorate the corrosion resistance and mechanical property of super austenitic stainless steel S31254. The precipitation of σ phase in S31254 containing B and Ce can be effectively inhibited by heat treatment to regulate trace elements. In this study, slow cooling combined low-temperature diffusion treatment (SCLDT) was adopted in S31254 containing B and Ce. Furthermore, the role of Ce was explored by comparing the precipitation behavior of samples with different Ce content. The results show that this new heat treatment strategy can better exert the inhibition effect of B and Ce on the precipitation of σ phase, and the inhibition effect is more obvious when the content of Ce is higher. It was found that the distribution of elements in the adjacent area of Ce at the GBs was almost the same as that in the matrix, which indicated that Ce could inhibit the formation of the precipitates along the GBs, and thus resulting in the precipitates distributed discontinuously. Besides, the B element was soluble in Mo-rich precipitates, and the B-containing precipitates was distributed in serrated pattern at GBs. In the 50Ce samples, serrated precipitates are more likely to form at the GBs, and the amount of precipitates was significantly reduced and discontinuities increased. Due to the homogeneous distribution of Cr in the serrated precipitates and their adjacent matrix zones, the phase interface has better resistance to intergranular corrosion.

Effect of Ce Content on the Microstructure and Mechanical Properties of Al-Cu-Li Alloy

In this work, the effects of Ce content (0.1%, 0.2%, and 0.3 wt%) on the microstructures and mechanical properties of Al-Cu-Li alloys were investigated. The results show that the grains of Al-Cu-Li alloy are refined by adding Ce element. When Ce content is less than 0.1%, the ultimate strength of the alloy increases with the increase of Ce content. However, the ultimate strength of the alloy decreases when Ce content is above 0.1%. For Al-Cu-Li alloy with different Ce content, the aging precipitation of T1 and θ′ phases play the main strengthening role. When Ce content increases from 0.1 to 0.3%, dynamic recrystallization is promoted during hot deformation. The recrystallization of the alloys is inhibited after T6 treatment with the increase of Ce content, which can be attributed to existence of the Al8Cu4Ce phases on the grain boundary. This work provides an economical and convenient method for improving the properties of Al-Cu-Li alloys by Ce addition.

Effect of Ce content on the hydrogen induced cracking of X80 pipeline steel

In this study, the effect of Ce content on hydrogen induced cracking (HIC) of X80 pipeline steel has been investigated. The results show that as the Ce content increased from 0 wt% to 0.0042 wt%, 0.016 wt% and 0.024 wt%, the HIC susceptibility of tested steels decreased first and then increased. The steel containing 0.016 wt% Ce possessed the lowest HIC susceptibility because Ce modified inclusions, promoted the formation of acicular ferrite, and decreased the number of hydrogen traps and intergranular cracks.

Effects of Ce content on microstructure evolution and magnetic properties for hot deformed Ce–Fe–B magnets

Understanding the evolution of phase and microstructure is a critical step to prepare high performance magnets. In this work, hot deformed (HD) Ce–Fe–B magnets with different Ce contents are prepared. The results demonstrate that the content of CeFe2 phase is enhanced with increasing Ce content. And its distribution changes from the sporadic distribution for Ce13.5Fe81B5.5 magnet to the mixed distribution consisting of large strip-shaped grains and dispersed distribution around main phase for Ce17Fe78B5 magnet to the nearly complete dispersed distribution for Ce21Fe74B5 magnet. These CeFe2 phase around main phase can increase magnetic isolation effect, improving the coercivity of HD magnet. In addition, it is found that a large amount of CeFe2 phase and equiaxed 2:14:1 phase grain without c-axis orientation surround each other, indicating that the CeFe2 phase is not favorable to the formation of c-axis orientation. Elemental metallurgical behavior reveals that Pr and Cu elements are segregated between platelet-shaped main phase grains, and however, for equiaxed grain region, Pr and Cu elements are enriched in CeFe2 phase. Based on the grain boundary diffusion (GBD), the coercivity, remanence and magnetic energy product are all improved significantly, increasing by 287%, 74%, and 371%, respectively, which is attributed to the formed (Pr, Ce)2Fe14B phase and increased magnetic isolation effects.

Effect of Ce content on the microstructure and mechanical properties of squeeze-cast Al–5Mg-2.2Si-0.6Mn alloys

The effect of Ce in amount of 0–0.5 wt.% on the microstructure and mechanical properties of the squeeze-cast Al–5Mg-2.2Si-0.6Mn alloys produced by squeeze casting technique was explored. The microstructure was observed by optical microscopy and scanning electron microscopy. The hardness and mechanical properties of the alloys were measured by Vickers hardness and tensile test. The microstructure of the squeeze-cast Al–5Mg-2.2Si-0.6Mn alloys is composed mainly of α-Al, Al–Mg2Si eutectic cells, the bulky lath-shaped Al8CeMn4 phase, Al2Mn3 and Al5Mn2Si5 phases after Ce is added. The results show that the addition of Ce leads to the grain refinement, which can improve the mechanical properties. When adding superfluous Ce, the formation of coarse and brittle Al8CeMn4 phase seriously reduces the mechanical properties of the alloy. With the increase of Ce content, the secondary dendrite arm spacing of different alloys decreases first and then increases, hence the hardness and tensile properties increase first and then decrease. The most remarkable improvement in the mechanical properties was acquired in the alloy with 0.10 wt.% Ce addition, the hardness reaches 48.1 HV, the ultimate tensile strength, yield strength and elongation are 265.5 MPa, 185.8 MPa and 5.8%, respectively.

Microstructures and Properties of In Situ (TiB2p+TiBw)/Cu Composites with Different Ce Content

(TiB2p + TiBw)/Cu composites are prepared by in situ reaction casting. The effect of Ce content on the microstructures, electrical conductivity, and tensile strength of (TiB2p + TiBw)/Cu composites are studied. The results show that the right amount of Ce can significantly refine the reinforcements and the copper matrix grains, and improve the morphology and distribution of the reinforcements. Correspondingly, the electrical conductivity and tensile strength of the composites also vary with the Ce contents, but the excess Ce can result in a deterioration of microstructures and properties, and the reasons are also discussed. Finally, a better comprehensive property (78.4 %IACS and 671 MPa) is obtained when the Ce content is 0.04 wt%, which is consistent with the microstructures.

Effect of Ce Content on Microstructure-Toughness Relationship in the Simulated Coarse-Grained Heat-Affected Zone of High-Strength Low-Alloy Steels

The study aimed to identify a moderate degree of Ce addition to improve the toughness in the simulated coarse-grained heat-affected zone (CGHAZ) of high-strength low-alloy steels, based on the effect of the Ce content on particle characteristics, microstructure and impact toughness. Three steels with 0.012 wt.%, 0.050 wt.% and 0.086 wt.% Ce content were subjected to 100 kJ/cm heat input in their thermal welding cycles. The particles and microstructures in the simulated CGHAZ of each steel were characterized and the impact-absorbance energy levels were measured at −20 °C. The results indicated that Ce2O2S inclusion compounds were gradually modified to CexSy-CeP and CeP with the increasing of the Ce content. A higher fraction of acicular ferrite was formed in the 0.012 wt.%-Ce-treated steel due to the lower mismatch between Ce2O2S and α-Fe. Furthermore, a lower fraction of M-A constituent was obtained in the 0.012 wt.%-Ce-treated steel. As a result, superior toughness and a typical amount of ductile fracture were detected in the simulated CGHAZ of the 0.012 wt.%-Ce-treated steel. Compared with the 0.012 wt.%-Ce-treated steel, a smaller prior austenite grain was observed in the 0.086 wt.%-Ce-treated steel because of the segregation of CeP at the grain boundary. However, the larger size and density of CeP led to poor toughness in the CGHAZ of the 0.086 wt.%-Ce-treated steel.

Effects of Ce content on the modification of Mg2Si phase in Mg-5Al-2Si alloy

The effect of Ce content (0–1.6 wt.%) on the modification of Mg2Si phase in the as-cast Mg-5Al-2Si alloy was investigated. The original Chinese script type Mg2Si phase was refined distinctly and transformed to dispersive block shape gradually by adding Ce element. The length of Chinese script type Mg2Si phase was reduced from 110 to 50 µm with increasing Ce content to 1.6 wt.%. The results calculated by Pandat software indicated that the added Ce element first combined with Si to form CeSi2 phase, which could serve as the heterogeneous nucleation of Mg2Si phase due to the small lattice mismatch of 7.97%. The modification of Mg2Si phase was mainly attributed to the facts that Ce changed the growth steps of Mg2Si phase and CeSi2 promoted the nucleation of Mg2Si phase. With increasing Ce content from 0 wt.% to 1.6 wt.%, the YS, UTS and EL at 150 °C were improved from 67.7 MPa, 91.2 MPa and 1.6% to 84.2 MPa, 128 MPa and 7.5%, respectively.

Effect of Ce Content on Properties of Al-Ce-Based Composites by Powder-in-Tube Method

Al-Ce based alloys have gained recent interest and have proven to have excellent strength without heat treatment and high thermal stability. Challenges with the production of Al-Ce samples from elemental powders arise due to the elemental material before alloying being susceptible to rapid oxidation. The methodology for making superconductive wire, powder-in-tube, was used as a consolidate Al and Ce elemental powder, and Al-8 wt % Ce-10 wt % Mg composite powder into bulk nanostructured material. Powder samples are fabricated in an inert controlled atmosphere, then sealed in a tube to avoid oxidation of powders. Therefore, most of the powder is used without much loss. We used 316 stainless-steel tubes as a sheathing material. For Al-xCe wt % (x = 8 to 14) samples of elemental powder, liquid phase sintering was used and for Al-Ce-Mg powder solid-state sintering. Characterization of the bulk consolidated material after sintering, and before and after heat treatment, was made using optical and Scanning Electron Microscope imaging, Energy Dispersive Spectroscopy, Microhardness and Rockwell Hardness test. We demonstrated that microstructure stability in Al-Ce-based specimens can be retained after thermomechanical processing. Densification was achieved and oxidation of powder was avoided in most samples. In addition, we found that Fe and Ni in the sheathing material react with Al in the process, and Ce concentration modifies the reactivity the sheath.

Producing Hydrogen from Steam Reforming of Bio-oil Derived Oxygenated Model Compounds by Utilizing Ce-Modified Ni/Attapulgite Catalysts

Steam reforming (SR) of bio-oil has been considered as one of the promising methods for hydrogen production. In this paper, cerium modified Ni/Attapulgite (ATP) catalysts were successfully synthesized by traditional chemical precipitation method and utilized for SR of various bio-oil derived oxygenated model compounds. The effect of Ce content on the structural properties of Ni/ATP was investigated by ICP-OES, N2 adsorption–desorption, XRD, H2-TPR and HRTEM characterizations. The results exhibited that 10Ce–Ni/ATP catalyst had the strongest metal-support interaction and highly dispersion of Ni species with smallest particle size of 6.21 nm. Therefore, it presented the maximum ethanol conversion of 97.21% and H2 yield of 83.15% at relative lower reaction temperature 500 °C during 4 h of SR of ethanol (SRE). In addition, it unfolded promising performance for SR of acetic acid (SRAA) and acetone (SRA). Furthermore, the influence of different oxygenates on the amount and nature of carbon deposits in used 10Ce–Ni/ATP catalyst was revealed by TG and Raman analyses. It found that the types of feedstock significantly affected the carbon species and amount and the formation of graphic layers around the Ni metal sites was the mainly factor for rapid deactivation of 10Ce–Ni/ATP during 4 h of SRA reaction.

Microwave Absorbing Properties of Pr-Co-Based Alloy with Ce Fabricated with Smelting Process

Due to the rapid development of electromagnetic wave technology, the problem of electromagnetic pollution needs to be solved. Rare earth metals are widely studied due to their unique structure. In this study, CexPr2−xCo17 (x = 0.0, 0.4, 0.6, 0.8) powders were prepared by vacuum arc furnace homogenization treatment and ball milling. The effects of Ce content on the microwave absorption performance of the CexPr2−xCo17 alloy powders were measured. The reflection loss of CexPr2−xCo17 powders at a given thickness of 1.8 mm was simulated by transmission line theory. The minimum reflection loss (RL) of the Pr-Co-based powders with the addition of Ce content of 0.8 reached −30.06 dB at 8.88 GHz with thickness of 1.7 mm, and the effective bandwidth (RL< −10 dB) reached about 1.86 GHz, meaning that the microwave absorbing performance of CexPr2−xCo17 powders can be optimized in X-band (8–12 GHz) and C-band (4–8 GHz) frequency.

Effect of Cerium Content on the Evolution of Inclusions and Formation of Acicular Ferrite in Ti-Mg-Killed EH36 Steel

Ce has been widely used in oxide metallurgy for modifying inclusions and refining microstructure. Effect of Ce contents on the evolution and characteristics of non-metallic inclusions and the formation of acicular ferrite (AF) in Ce-treated Ti-Mg-killed EH36 steel was investigated. The results showed that the main type of inclusions in Ti-Mg deoxidized steel was MgO·Al2O3-MnS. After 0.014%, 0.024% and 0.037% Ce were added into the steels, dominant inclusions became CeAlO3-MgO-MnS, Ce2O2S-MgO-MnS and Ce2O2S-MnS, respectively. The precipitation of pure MnS was suppressed in the steel with 0.024% Ce, while the number density of total inclusions increased significantly in the steel with 0.037% Ce, causing the inclusions distributing densely. Ce addition refined the microstructure of tested steels by promoting AF formation and polygonal ferrite distributing evenly. Dispersive distribution, low lattice mismatch against α-Fe, as well as lower number density of pure MnS caused the highest number density of effective inclusions (nucleus of AF formation) in 0.024% Ce-treated steel.

Synthesis of eutectic Al–18Ce alloy and effect of cerium on the PEO coating growth

Plasma electrolytic oxidation (PEO) is an attractive technique for enhancing the wear resistance, hardness and aqueous medium corrosion of aluminum alloys. Phase composition, microstructure and elemental distribution determine the mechanical-corrosion properties of coating. In this study, Al–18Ce binary alloys were synthesized and the effect of Ce (cerium) on the formation mechanism of PEO coating was investigated. The pure Al and eutectic Al–18Ce binary alloy were coated by PEO for 15 min and the effect of Ce content on behavior and properties of the coatings were examined. α-Al and Al11Ce3 phases were observed in the XRD pattern of Al–Ce alloy. The average values of hardness on Al11Ce3 precipitate and the hardness values of Al/Al11Ce3 regions were found to be 365 ± 35 HV and 75.5 ± 2.5 HV, respectively. It was found that the eutectic Al–Ce alloy microstructure contained α-Al, the fine eutectic Al11Ce3 lamellar and needle-like Al11Ce3 precipitates. While α-Al2O3, γ-Al2O3 and 3Al2O3·2SiO2 phases were identified on all the coatings, CeO2 phase was identified on the coatings of Al–18Ce alloy. The α-Al2O3 phase was detected on the coating synthesized on the pure Al, while the increased amount of Ce in Al alloys reduced the formation of α-Al2O3 phase. The size and the number of porosity levels of the coatings increased with increasing amount of Ce in Al. The microhardness profile throughout the coating/substrate interface to surface of the coating decreased for the coatings. The diameter of tiny globular particles on the coating/substrate (C/S) interface for Al–Ce alloy was found to be approximately 0.5–1.5 μm.

Effects of Ce Content in Precursor Alloys on Catalytic Properties of CeO2 Nanorods

In this study, Al-Ce alloy ribbons with Ce content (at.%) ranging from 6% to 12% were prepared by a simple melt-spinning method. The microstructure, phase structure, porosity and catalytic CO oxidation activity of dealloyed and calcined ribbons were analyzed. The results revealed that all the CeO2 catalysts showed a nanorod framework structure, and the size of the CeO2 nanorods became finer with the decrease of Ce content in the precursors. The specific surface area was the largest and porous size was the smallest for dealloyed and calcined Al92Ce8 ribbons. The CeO2 nanorod prepared from the Al92Ce8 precursor exhibited the highest catalytic activity, with total CO conversion at 320°C. The larger specific surface area could provide more gas diffusion paths and richer reaction active sites for CO oxidation.

Hydrogen production from ethanol steam reforming: Effect of Ce content on catalytic performance of Co/Sepiolite catalyst

A series of Co-xCe/Sepiolite (SEP) catalysts were synthesized and evaluated in ethanol steam reforming (ESR) for hydrogen production. The properties of calcined and reduced catalysts were characterized by N2 adsorption-desorption, XRD, H2-TPR, XPS and HRTEM. These results indicated that Co metal dispersion and reducibility of Co-xCe/SEP catalysts were improved by Ce addition. In addition, the interaction between active metal phase and SEP support was significantly improved by Ce promoter, which could suppress the sinter and re-oxidation of Co metal phase during the catalytic test. Meanwhile, HRTEM and XPS analysis demonstrated a portion of cobalt ions incorporated into CeO2 lattice, enhanced the formation of oxygen vacancies, which could react with coke precursors on catalyst surface to remove carbon deposition. During the 4 h of ESR reaction under S/C = 3, T = 600 °C and WHSV = 21.5 h−1, Co-0.3Ce/SEP (Ce/Co mole ratio = 0.3) showed the highest carbon conversion rate of 90.8% and H2 yield of 69.1%. Combining the characterizations for spent catalysts, it was found that the unique catalytic performance of Co-0.3Ce/SEP was attributed to strong synergy effect among Co metal active sites, excellent thermostability of SEP and the formation of oxygen vacancies in CeO2. Additionally, Co-0.3Ce/SEP showed the exciting stability during 100 h on stream.

The effect of Ce content on structure and stability of Gd1-xCexPO4: Theory and experiment

The structure distortion, bonding character, defect stability and chemical stability of Gd1-xCexPO4 (x = 0, 0.25, 0.5, 0.75 and 1) have been investigated by combined with experimental and first principles calculations to understand the effect simulate actinides on the structural stability of Gd-monazite. The result shows that the Gd1-xCexPO4 (x = 0–1) ceramics could be prepared at 1450 °C, and Ce3+ is easily incorporated into Gd-monazite lattice. The structural analysis indicates that the symmetry of [GdO9] polyhedron decreases with increasing Ce content. The evolution of Gd defect stability and chemical stability in Gd1-xCexPO4 (x = 0–1) is tightly associated with the distortion of [GdO9] polyhedron, in which a greater distortion will induce more unstable. The best chemical stability in pH = 3 and 11 leachates is CePO4, followed by GdPO4, Gd0.75Ce0.25PO4, Gd0.5Ce0.5PO4, and finally Gd0.25Ce0.75PO4, revealing the GdPO4 monazite is perfectly suitable to immobilize actinides with relative low dose ratio.