Addition Of Gd Research Articles

Effects of Gd on the microstructure and mechanical properties of GdxCoCrFeNiV0.4 high-entropy alloys

This study investigated the microstructure and mechanical properties of GdxCoCrFeNiV0.4 alloys. Various techniques such as XRD, SEM, EBSD, and TEM were utilized, alongside hardness and compression tests at room temperature. The findings revealed that the high-entropy alloy without Gd element exhibited a single face-centered cubic (FCC) phase. Upon the introduction of Gd element, the phase composition shifted to FCC + hexagonal structure (HS) phases, and further addition of Gd resulted in the presence of FCC + HS + body-centered cubic (BCC) phases. Additionally, the inclusion of Gd element led to the precipitation of Gd-rich particles within the alloy. The Vickers hardness test results revealed a significant increase in alloy hardness as the Gd content rose, from 177.5 HV for Gd0 to 848.4 HV for Gd0.4. This suggests that the presence of the HS phase and BCC phase notably influences alloy hardness. Furthermore, compressive test outcomes demonstrated that the alloy's yield strength rose from 173.74 MPa for Gd0 to 1356.17 MPa for Gd0.3 with increasing Gd content. However, the excessive addition of Gd elements results in significant precipitation of V and Cr elements, leading to grain coarsening, adversely affecting its mechanical properties. The high strength of Gd-containing high-entropy alloys can be attributed to various strengthening mechanisms, such as solid solution strengthening, the presence of the HS phase, the precipitation of a small number of Gd-rich particles, and the grain refinement caused by the addition of Gd.

Construction of CdS nanosphere with rare earth metal modification over acid theory with boosted photocatalytic hydrogen reaction

Absorption of light, surface reaction and carriers transfer are three main aspects that affect the whole photocatalytic process and activity. Surface modification strategy is widely adopted to promote the light response while still presented poor carriers transfer. Therefore, rare earth metal was introduced to regulate the surface property of the photocatalyst, which shows enhanced photocatalytic performance of 4567.0 μmol h−1 g−1 under optimal rare earth doping compare to 1553.3 μmol h−1 g−1 of pure CdS. The addition of Gd could expose more reactive centers and reduce the recombination of photo-generated carriers. Meanwhile, the doping of Gd could extend the light absorption and accelerate the hydrogen production kinetics.

Increasing heat resistance of a Mg-Sm-Zn alloy via minor gadolinium addition

The addition of minor gadolinium (Gd) into Mg-4Sm-0.6Zn-0.4Zr alloy significantly enhances high-temperature strength and creep resistance, such as a decrease in the minimum creep rate by approximately five times and an increase in the yield strength by around 40 MPa at 200 °C. The presence of Gd results in the co-precipitation of both prismatic β-type and basal γ-type phases during creep, whereas only the basal γ-type phase is present in the Gd-free alloy. The prismatic β-type and basal γ-type phases are oriented perpendicular to each other in space, creating a closed configuration that effectively blocks dislocation motions compared to single basal γ-type precipitates. Therefore, the improved creep resistance in the Gd-enriched alloy is mainly attributed to the co-precipitation of prismatic β-type and γ-type precipitates during creep. Furthermore, rare earth (RE) atoms inherently provide stable solute hardening at high temperatures, which contributes to the increased high-temperature strength. The addition of Gd also enhances grain boundary stability by promoting the formation of more Mg3RE phases, thereby further enhancing the creep strength. These findings offer insights into the development of highly creep-resistant Mg alloys with low RE concentrations.

Influence of solute content and cooling rate on the preparation of semi-solid slurries for novel creep-resistant Mg-Gd-Ca-Zr alloys

The semi-solid Mg-Gd-Ca-Zr alloys slurries with fine and spherical α-Mg particles were successfully prepared. The influence of solute Gd and Zr contents, and cooling rate on the morphological evolution of α-Mg are systematically investigated. The results showed that addition of Zr will turn the coarse dendritic α-Mg particles into fine and globular particles. With the increase of Zr addition from 0 to 0.6 wt%, the particle size decreases, and the particle density and shape factor increase continuously. With the change of solute Gd content from 5 to 15 wt% in the Mg-yGd-2Ca-0.6Zr alloy, the particle size of α-Mg particles decreases continuously, and shape factor increases continuously. With cooling rate decreases from 3 to 1.5 °C/min, the α-Mg particles are slightly coarsened and the morphology are kept nearly globular, while with further decreasing into 0.5 °C/min, the α-Mg particles are severely coarsened and turned into irregular shape. The optimal Zr addition is ∼0.6 wt% and Gd addition is no less than 10 wt%, and the optimal cooling rate is 1.5–3 °C/min. The mechanisms for obtaining fine and spherical α-Mg particles through Zr and Gd additions are discussed to be different roles of heterogenous nucleation effects and growth restriction effects.

Highly Tuning of Sunlight-Photocatalytic Properties of SnO2 Nanocatalysts: Function of Gd/Fe Dopants

Gd/Fe-SnO2 nanopowders as novel photocatalysts for the active removal of Rose Bengal dye and methyl parathion pesticide were synthesized with a low-cost coprecipitation route. The X-ray diffraction analysis of SnO2, Sn0.96Gd0.02Fe0.02O2 and Sn0.94Gd0.02Fe0.04O2 nanopowders proved the formation of a tetragonal phase of tin oxide with average crystallite sizes in the range of 13–18 nm. The Fourier transform infrared (FTIR) spectra of all samples displayed the characteristic absorption bands of SnO2. The nanopowder of the pure SnO2 sample, as seen in its transmission electron microscope (TEM) image, contains spherical-like particles of variable sizes. The TEM images of the Sn0.96Gd0.02Fe0.02O2 and Sn0.94Gd0.02Fe0.04O2 powders revealed the synthesis of fine spherical nanoparticles. Based on the TEM images, the average particle size of the pure, (Gd, 2 wt% Fe) and (Gd, 4 wt% Fe) codoped SnO2 nanopowders was estimated to be 14, 10 and 12 nm, respectively. After the addition of (Gd, 2 wt% Fe) and (Gd, 4 wt% Fe) to the SnO2 structure, the band gap energy of SnO2 was reduced from 3.4 eV to 2.88 and 2.82 eV, respectively. Significantly, the Sn0.96Gd0.02Fe0.02O2 nanocatalyst exhibited a high removal efficiency of 98 and 96% for Rose Bengal dye and methyl parathion pesticide after activation by sunlight for 35 and 48 min, respectively. Furthermore, this catalyst has shown perfect mineralization as well as high stability properties for the treatment of Rose Bengal dye and methyl parathion pesticide. These results suggest the suitability of the Sn0.96Gd0.02Fe0.02O2 nanocatalyst for the treatment of agriculture and industrial effluent under sunlight light energy.

Mitigation of strength-ductility trade-off of CoCrNi medium entropy alloys with heterogenous structure by controlled Gd addition and annealing

In this work, we synthesized a series of (CoCrNi)100–xGdx (x = 0/0.3/0.5/1.0) medium entropy alloys (MEAs) using arc melting followed by homogenization, hot-rolling, and annealing at 700, 800, and 900 °C for 1 h. The effects of Gd content and annealing temperature on the microstructures and mechanical properties of Gd-doped CoCrNi MEAs were investigated. The heterogenous microstructure, consisting of the deformed grains, recrystallized grains and precipitates of GdNi5 phase, was obtained in the present study and it exhibited an excellent combination of strength and ductility. The optimum mechanical properties were obtained for CoCrNi MEA with 0.3–0.5 at.% Gd addition and annealed at 700 °C for 1 h to yield the heterogenous microstructure in the present study, and it had the tensile strength of ∼1.3 GPa and fracture strain of 30–40%. The synergetic hardening mechanisms included solid solution, precipitation, grain refinement, nanotwinning and pre-existing dislocation hardening. The relations among compositions, microstructures and mechanical properties of (CoCrNi)100–xGdx MEAs were addressed.

Anelasticity of Mg-Mn and Mg-Gd alloys

Anelastic relaxation at sub-resonance frequency (from 0.01 to 100 Hz), temperature (from 0 to 450°C) and amplitude (ε0 from 5×10−5 to 10−3) range in binary Mg-0.8 wt%Mn (0.36 at%) and Mg-2 wt%Gd (0.31 at%) in as-extruded and annealed states was experimentally studied and analyzed, to characterize acting thermally activated and structural relaxation effects. Activation parameters for thermally activated anelastic effect and structural studies suggest that it is the grain boundary relaxation with dominating large angle boundaries, while the high-temperature background is mainly controlled by dislocations sliding. Pseudo peak at ∼290 °C (Mg-Mn) and ∼410 °C (Mg-Gd) is the result of the recrystallization process in the as-extruded samples, which indicates that the addition of Gd restricts the recrystallization of Mg compared with the addition of Mn. Analysis of amplitude dependencies of internal friction in the frames of Granato and Lücke approach suggests higher density of movable dislocations in as-extruded Mg-Mn alloy.

First-principles study of binary and ternary phases in Mg-Gd-Ni alloys

Given the high demand for magnesium alloys across industries, it's crucial to enhance their performance by developing alloys with superior characteristics. The performance of magnesium alloys is closely related to the properties of the precipitated phase. However, there has been insufficient exploration of the mechanical properties of precipitated phases in Mg-Gd-Ni alloys. Hence, this paper calculates the formation energy, electronic structure, elastic modulus, and elastic anisotropy of the precipitated phase in Mg-Gd-Ni alloys using first principles. Calculations of formation energies and elastic constants demonstrate that MgGdNi4, Mg2Ni, 18R-LPSO, Mg2Gd, and 14H-LPSO possess commendable thermodynamic and mechanical stability. Elastic modulus calculations reveal a significant increase in the elastic modulus of magnesium, especially the bulk modulus, upon the addition of Gd and Ni elements, increasing from 34.5 GPa to a peak of 84.9 GPa. Furthermore, the strength increments of the corresponding precipitated alloys, calculated based on the elastic modulus, underscore MgGdNi4 as exhibiting the most significant strength increment. The elastic anisotropy of each second phase is evaluated using the elastic anisotropy factor, the three-dimensional surface, and the projection onto each two-dimensional plane. The order of elastic modulus anisotropy for shear and Young's modulus is MgGdNi4 > Mg2Ni > 18R-LPSO > Mg2Gd > 14H-LPSO. This study provides valuable data for regulating properties in magnesium alloys.

Microstructure and texture transformation of wedge-shaped rolled 3%Y2O3p/ZGK200 composites

The microstructure and texture transformation of 3%Y2O3p/ZGK200 composites after wedge-shaped rolling were investigated. The 3%Y2O3p/ZGK200 composites could be wedge-shaped rolled for 50 % reduction without obvious edge cracks. Basal <a> slip, prismatic <a> slip and pyramidal <c+a> slip detected by in-grain misorientation axes (IGMA) combined with Schmid factor (SF) analysis were abundantly activated during the whole rolling process. Different from the activation of all kinds of dislocation slips, many {10 1‾ 2} extension twins and few {101‾ 1}-{101‾ 2} secondary twins were activated with a reduction of 10 %. With increasing reduction from 30 % to 50 %, {101‾ 1}-{101‾ 2} secondary twins and {101‾ 1} compression twins started to play more important roles. Finally, the rolled deformed grains were elongated along rolling direction (RD) with abundant twins. During the whole rolling process, few recrystallized grains were found in the composites due to the effect of Gd addition. The {101‾ 2} extension twins whose c-axis oriented along normal direction (ND) should be attributed to the formation of basal texture, which was kept unchanged during the whole rolling process.

Gd Effect on Micro-Crystal Structure and Thermomagnetic Behavior of NiMnSn Magnetic Shape Memory Alloy

In this study, the rare earth Gadolinium (Gd) element was added to the NiMnSn alloy, which is an alternative to the NiMnGa alloy group, with the increasing popularity of magnetic shape memory alloys. Since rare earth elements have strategic importance for our country in recent years, Gd element has been preferred in this study. X-rays and SEM-EDX analysis were performed to determine the morphological properties of the crystal structure and microstructure of the alloys. Magnetic measurements of the alloys were made with the physical property measuring device and it was determined that the magnetization values decreased with the addition of Gd.

Evolution of bimodal-structure and achieving ultra-high yield strength in the as-extruded ZK70 alloy via Gd addition

Achieving ultra-high tensile yield strength over 400 MPa in RE modified Mg–Zn-based alloys using conventional thermomechanical processing is a challenging task. In this study, we successfully produced a Mg–7Zn–2Gd–0.5Zr (wt. %) alloy with exceptional strength through traditional hot-extrusion techniques. This alloy exhibits a tensile yield strength of 440 MPa and an acceptable ductility of 4.5%, surpassing a majority of previously reported Mg–Zn-RE-based alloys. Our findings demonstrate that the addition of Gd in Mg–Zn-based alloys effectively retards dynamic recrystallization (DRX) during extrusion, leading to the formation of a distinctive bimodal structure comprising approximately 13.8% coarse un-recrystallized (unDRXed) grains and about 86.2% fine DRXed grains. Furthermore, the alloying effect of Gd enhances particle density, including micron-sized particles and dynamic nano-precipitates. These dynamic precipitates play a crucial role in impeding dislocation movement during extrusion, thereby contributing to the formation of bimodal structure. Additionally, both nano-precipitates and segregation of Zn and Gd atoms towards grain boundaries facilitate the formation of fine DRXed grains through pinning effect. Consequently, the significantly increased tensile yield strength observed in our Gd-modified alloy can be attributed to multiple strengthening mechanisms: fine DRXed grains, strong texture exhibited by unDRXed grains, numerous dynamic precipitates, high-density residual dislocations, and co-segregation of solutes. However, the formation of bimodal structure worsens the yield asymmetry of the Gd-modified alloy due to its strong basal texture. These results provide a valuable insight for further development efforts aimed at achieving ultra-high-strength Mg–Zn-RE-based alloys.

Revealing the effect of Gd alloying on oxidation resistance and oxide film protection performance of AZ80 alloy

The high-temperature oxidation behaviors and oxide film characteristics as well as corrosion protection of AZ80 and AZ80–0.75Gd (wt%) alloys were investigated to research the effect of Gd addition on oxidation resistance and oxide film corrosion protection performance of AZ80 alloy. The results showed that with 0.75 wt% Gd alloying, Gd2O3 appeared in oxide film, which promoted densification of oxide film and translation of the superlinear rate law oxidation kinetics to approximate parabolic rate law oxidation kinetics of alloy. And after erosion of oxide film containing Gd2O3, the corrosion products were extensively nodulated, resulting in corrosion passivation and showing protection effect.

Microstructures and mechanical properties of a γ-TiAl alloy modified by Gd additions

The microstructural evolutions and room-temperature tensile properties of Ti-45Al-2.5Nb-1.5Mo-(0-0.2)Gd were investigated in details. Experimental result revealed that there were precipitated particles, involving Gd2TiO5 and GdAl3, distributing within the microstructure of the Gd-containing TiAl alloys, and the increase in the Gd addition resulted in the aggregation of Gd-containing particles, forming a network structure along grain boundary and colony boundary. The addition of Gd also had a significant refining effect on the average inter-lamellar spacing. The ultimate/yield strength and elongation increased first and then decreased with the content of Gd. Gd addition did not change the mixed fracture mode of crack propagation along and across the lamellae. In the plastic deformation process of Gd-containing sample, except for dislocation gliding, twinning-controlled deformation mode occurred, contributing to the improvement of mechanical properties. Moreover, dislocations could directly cut through the small-size Gd-containing particle, while some dislocations would continue to slip via bypassing the large-size Gd-containing particle.

The effect of Gd on the microstructure and electrochemical properties of Mg-Ni-based alloys

The Mg-Ni-based alloys have been extensively investigated as negative electrode materials in Nickel-Metal Hydride (Ni-MH) batteries. In this work, two Mg-Ni-based samples (Mg71Ni29 and Mg72.6Ni25.3Gd1.1) were prepared by means of melting. The X-ray diffraction (XRD), scanning electron microscope (SEM), galvanostatic charging/ discharging and other electrochemical measurements were used for the investigation. The results show that the Mg71Ni29 and Mg72.6Ni25.3Gd1.1 alloys include the characteristic peaks of Mg2Ni and the less strong characteristic peaks of Mg and MgNi2 phases. The diffraction peak of the major phase Mg2Ni of the Mg72.6Ni25.3Gd1.1 alloy is shifted to a small angle and its unit cell volume increases. With the addition of Gd, the alloy electrodes exhibits better cycling stability. After 50 charge/ discharge cycles, the capacity retention rate of the alloy electrode increase from 16% (Mg71Ni29) to 22% (Mg72.6Ni25.3Gd1.1). However, the maximum discharge capacity of the alloy electrode decrease from 134.3 mAh/g (Mg71Ni29) to 91.9 mAh/g (Mg72.6Ni25.3Gd1.1). The Mg72.6Ni25.3Gd1.1 alloy possess lower limiting current density IL and exhibit relatively high corrosion resistance against the alkaline solution. After Gd doping, the charge transfer capacity of the Mg72.6Ni25.3Gd1.1 alloy surface is increased.

Effects of the Simultaneous Addition of Gd and Mn on the Microstructures and Mechanical Properties of Mg-Bi Alloys

Effects of the Simultaneous Addition of Gd and Mn on the Microstructures and Mechanical Properties of Mg-Bi Alloys

Effect of rare-earth element Gd addition on microstructure of TNM-based TiAl alloys

The effects of gadolinium (Gd) on the microstructures of Ti-43.5Al-4Nb-1Mo-0.1B-XGd (X = 0, 0.03, 0.06, 0.1 at.%) alloys were systematically studied. The results show that all microstructures of casting alloys are nearly lamellar, nevertheless, the precipitations of Gd2O3 are formed by the combination of Gd atoms with O atoms, playing a role of heterogeneous nuclei refining both lamellar colonies and the lamellar spacing. However, the phase transition pathways of all alloys were L → L + β →β→ α + β → α + β/B2 + γ → α2 + B2 + γ. After heat treatment, the microstructures were nearly lamellar, but the lamellar spacing was refined by Gd2O3.

Influence of gadolinium content on magnetic property and oxidation mechanism of Fe-B-Nb-Gd metallic glass

In this work, we use the rapid solidification technique to prepare five kinds of metallic glasses with different Gd content, and investigate in depth the influences of Gd content on the amorphous formation capability, thermal stability, and magnetic properties of (Fe&lt;sub&gt;73&lt;/sub&gt;B&lt;sub&gt;22&lt;/sub&gt;Nb&lt;sub&gt;5&lt;/sub&gt;)&lt;sub&gt;100–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Gd&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; (&lt;i&gt;x&lt;/i&gt; = 0, 0.5, 1.0, 1.5, 2.0) alloys. By comparing the microstructural morphology and solute distribution of oxidation products before adding Gd and those after adding Gd, the amorphous oxidation mechanism is analyzed systematically. With the addition of Gd, the atomic size difference of the alloys exceeds 13%, and the configuration entropy increases from 7.27 kJ/(mol·K) to 9.44 kJ/(mol·K). The glass-forming ability of the alloy is significantly improved. The increase of Gd content can increase the glass transition temperature of the alloy to 864 K, and the undercooled liquid region can reach 73 K, significantly enhancing the thermal stability of the metallic glasses. The Gd limits the local anisotropy of the alloy and reduces the density of quasi-dislocation dipole defects. This can effectively reduce the pinning sites that hinder the rotation of magnetic domain walls, thereby improving the soft magnetic property. By comparing with the metallic glasses without Gd, only 2% (atomic percentage) Gd can reduce the coercivity by 8%. Moreover, the Gd makes the metallic glasses more sensitive to temperature variation in the oxidation process, and the temperature of the maximum oxidation rate is reduced by 15 K. However, their antioxidant performance does not deteriorate. The Gd atoms are influenced by binding energy and migrate to the surface, forming Gd-rich oxides. They fill surface defects and occupy a large part of the top space, leading to the structure becoming more compact near the surface. This structure reduces the channels for oxygen atoms to diffuse through the microstructure interface, which helps to improve antioxidant capability. This work provides a new approach for designing high performance Fe-based metallic glasses.

Characterization of Various Stainless Steels Containing Gadolinium as Thermal Neutron Absorbing and Shielding Materials

Developing next-generation thermal-neutron-shielding and -absorbing materials for the safe storage and transportation of spent nuclear fuel is a topic of active research in academia. Gadolinium (Gd) boasts superior neutron absorption capacity compared with other nuclei. Consequently, it has garnered significant attention as a potential replacement for boron in spent nuclear fuel (SNF) applications. In this study, the austenitic stainless steels 304 and 316 and the duplex stainless steel 5A were reinforced with 2 wt.% of gadolinium to explore their thermal-neutron-absorbing efficiency. Their properties were then compared with commercial-grade borated stainless steel, as per ASTM standard A887. After the inclusion of Gd, both the yield strength and ultimate tensile strength of the alloys slightly increased, which was attributed to the evenly distributed Gd intermetallics within the matrix. However, the elongation rate was reduced. The Charpy impact absorption energy also decreased. The influence of the Gd intermetallic was further explored by examining the fractography. While the corrosion resistance of the alloy slightly diminished after the addition of Gd, its neutron absorption capacity demonstrated superior performance, especially when the Gd content was equivalent to that of boron. Although most properties of the experimental alloy deteriorated after the Gd addition, they still outperformed commercial borated stainless steel, suggesting that this alloy might be a promising candidate for SNF applications.

Tailoring the degradation rate of magnesium-lithium alloy with alloying elements of gadolinium and nickel

To explore lightweight degradable materials that are more suitable for fracturing ball, Mg-8Li-4Gd-xNi (x = 0, 0.5, 1, 1.5 wt%) alloys for fracturing ball in petroleum extraction were prepared by vacuum induction melting. The features and formation of long-period stacking ordered (LPSO) doped with gadolinium (Gd) and nickel (Ni) were characterized. And the relationship between the degradation rate of alloys and the structure of LPSO in duplex Mg-Li alloys is investigated. The results show that network 24 R LPSO phase and punctate GdNi3 phase are formed with the addition of Gd and Ni. With the increase of Ni content, the shape of LPSO changes from intermittent network to continuous network and turns into an intermittent network again. The Mg-8Li-4Gd-1.5Ni alloy shows a significant increment in weight loss rate compared with the Mg-8Li-4Gd alloy by 75 times. Atomic force microscope (AFM) results show that the addition of Ni increases the potential difference between the second phase and the β-Li phase from 220 mV to 504 mV. It is difficult for forming LPSO due to higher fault energy when the atomic ratio of Gd to Ni is lower than 4:3, which promotes the LPSO to intermittent network. LPSO and GdNi3 provide higher potentials as cathodes in corrosion, forming a loose and porous corrosion product layer in the alloy. With the increase of Ni content, micro-galvanic corrosion effect is increased which results in a significantly higher corrosion rate of the alloy.

Effect of ultralow Dy and Gd contents on surface crystallization and domain wall motion of FeCuSiBNbMo alloys

Surface crystallization of Fe-based melt-spun ribbons with high saturation induction leads to the formation of coarse grains after nanocrystallization, which results in a deterioration of the soft magnetic properties. Herein, doping with an ultralow concentration (0.1 at.%) of RE (RE = Dy and Gd) inhibits the surface crystallization of melt-spun FeCuSiBNbMo samples using industrial-grade Nb–Fe raw materials. This inhibition of surface crystallization promotes the formation of uniform and ultrafine nanograins after optimal annealing. Furthermore, the movement of domain wall is significantly affected by the presence of large grains (∼600 nm) in the free surface, which exerts a strong pinning effect on the domain wall motion. This pinning effect can be attributed to the higher magnetic anisotropy energy of the free surface compared to that of the nanocrystal region. The low coercivity observed in the samples with 0.1 at.% Dy and Gd addition is ascribed to the presence of dense and ultrafine nanocrystals, low effective magnetic anisotropy, and a weak pinning effect. This work provides insights into the relationship between surface crystallization, coercivity, domain wall motion, and magnetic anisotropy energy in Fe-based nanocrystalline ribbons.