Pub Date : 2024-11-23DOI: 10.1016/j.jallcom.2024.177728
Yuchao Jin, Lixi Tian, Zhou Huang, Fang Wang
Mg-Al-Ca-based alloys are highly susceptible to electrochemical corrosion due to the micro-galvanic corrosion induced by the large potential gap between the cathodic second phase and the anodic α-Mg matrix. This study reports a new strategy of improving their corrosion resistance by enhancing the barrier effect of the cathodic phase skeleton based on a Mg-5Al-3Ca-xZn alloy. The results indicate that the supersaturation of Zn in the C36-(Mg,Al)2Ca phase skeleton, combined with the further formation of Ca2Mg6Zn3 through a peritectic reaction, significantly increases the potential difference between the second-phase skeleton and the matrix, however, the corrosion rate of the alloy in the 3.5 wt.% NaCl solution anomalously decreases accordingly. It suggests that the corrosion kinetics of this alloy are governed by the barrier effect of the continuous cathode phase skeleton, outweighing the micro-galvanic effect that dominates the corrosion process for most magnesium alloys. A new understanding of the barrier effect of the cathodic phase based on the local pH variation is proposed. This study offers a new perspective for the development of high-Ca magnesium alloys that exhibit superior electrochemical corrosion resistance.
{"title":"Improving the electrochemical corrosion resistance of a high-Ca heat-resistant magnesium alloy by enhancing the barrier effect of the cathodic phase skeleton","authors":"Yuchao Jin, Lixi Tian, Zhou Huang, Fang Wang","doi":"10.1016/j.jallcom.2024.177728","DOIUrl":"https://doi.org/10.1016/j.jallcom.2024.177728","url":null,"abstract":"Mg-Al-Ca-based alloys are highly susceptible to electrochemical corrosion due to the micro-galvanic corrosion induced by the large potential gap between the cathodic second phase and the anodic α-Mg matrix. This study reports a new strategy of improving their corrosion resistance by enhancing the barrier effect of the cathodic phase skeleton based on a Mg-5Al-3Ca-xZn alloy. The results indicate that the supersaturation of Zn in the C36-(Mg,Al)<sub>2</sub>Ca phase skeleton, combined with the further formation of Ca<sub>2</sub>Mg<sub>6</sub>Zn<sub>3</sub> through a peritectic reaction, significantly increases the potential difference between the second-phase skeleton and the matrix, however, the corrosion rate of the alloy in the 3.5<!-- --> <!-- -->wt.% NaCl solution anomalously decreases accordingly. It suggests that the corrosion kinetics of this alloy are governed by the barrier effect of the continuous cathode phase skeleton, outweighing the micro-galvanic effect that dominates the corrosion process for most magnesium alloys. A new understanding of the barrier effect of the cathodic phase based on the local pH variation is proposed. This study offers a new perspective for the development of high-Ca magnesium alloys that exhibit superior electrochemical corrosion resistance.","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"255 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142690950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Highly active and stable electrocatalysts are highly desired for the hydrogen evolution reaction (HER) in water electrolysis. In this study, a ruthenium-ruthenium phosphide heterojunction (Ru-Ru2P) anchored on phosphorus-doped graphene (PCSG) was fabricated via a mild molten salt template method. The graphene was synthesized from discarded coconut shells sourced from Hainan. We found that the heterojunction structure could accelerate electron transfer, while the graphene provided more exposed active sites, significantly enhancing the HER activity of the catalyst. The catalyst prepared at 800 °C with 30 mg of RuCl3 (Ru-Ru2P/2D-PCSG-800) exhibited low HER overpotentials of 31 mV in alkaline and 57 mV in acidic electrolytes at a current density of 10 mA cm-2, respectively, which were comparable to those of commercial 20% Pt/C catalyst (36 mV in alkaline and 40 mV in acidic electrolytes). Moreover, the catalyst demonstrated high stability with no significant change in current density after 125 hours of operation. Density functional theory calculations revealed that the Ru-Ru2P heterojunction could rearrange charge and modify the Ru d-band center, optimizing the adsorption energy of active ⁎H (|ΔG⁎H|) and breakage energy of ⁎H-OH bond (ΔGH2O).
水电解中的氢进化反应（HER）需要高活性和高稳定性的电催化剂。本研究采用温和的熔盐模板法，在掺磷石墨烯（PCSG）上锚定了钌-磷化钌异质结（Ru-Ru2P）。石墨烯由海南废弃的椰子壳合成。我们发现，异质结结构可以加速电子转移，而石墨烯则提供了更多暴露的活性位点，从而显著提高了催化剂的 HER 活性。用 30 毫克 RuCl3 在 800 °C 下制备的催化剂（Ru-Ru2P/2D-PCSG-800）在 10 mA cm-2 的电流密度下，在碱性电解质中和酸性电解质中分别表现出 31 mV 和 57 mV 的低 HER 过电位，与商业 20% Pt/C 催化剂（在碱性电解质中和酸性电解质中分别为 36 mV 和 40 mV）相当。此外，该催化剂具有很高的稳定性，在运行 125 小时后电流密度没有发生显著变化。密度泛函理论计算表明，Ru-Ru2P 异质结可以重排电荷并改变 Ru d 带中心，优化活性⁎H 的吸附能（|ΔG⁎H|）和⁎H-OH 键的断裂能（ΔGH2O）。
{"title":"Anchoring Ru-Ru2P heterojunction on P-doped graphene for enhanced HER performances of water electrolysis","authors":"Longyang Liu, Zichen Wang, Xueyan Zhang, Lijie Luo, Yongjun Chen","doi":"10.1016/j.jallcom.2024.177725","DOIUrl":"https://doi.org/10.1016/j.jallcom.2024.177725","url":null,"abstract":"Highly active and stable electrocatalysts are highly desired for the hydrogen evolution reaction (HER) in water electrolysis. In this study, a ruthenium-ruthenium phosphide heterojunction (Ru-Ru<sub>2</sub>P) anchored on phosphorus-doped graphene (PCSG) was fabricated via a mild molten salt template method. The graphene was synthesized from discarded coconut shells sourced from Hainan. We found that the heterojunction structure could accelerate electron transfer, while the graphene provided more exposed active sites, significantly enhancing the HER activity of the catalyst. The catalyst prepared at 800 °C with 30<!-- --> <!-- -->mg of RuCl<sub>3</sub> (Ru-Ru<sub>2</sub>P/2D-PCSG-800) exhibited low HER overpotentials of 31<!-- --> <!-- -->mV in alkaline and 57<!-- --> <!-- -->mV in acidic electrolytes at a current density of 10<!-- --> <!-- -->mA<!-- --> <!-- -->cm<sup>-2</sup>, respectively, which were comparable to those of commercial 20% Pt/C catalyst (36<!-- --> <!-- -->mV in alkaline and 40<!-- --> <!-- -->mV in acidic electrolytes). Moreover, the catalyst demonstrated high stability with no significant change in current density after 125<!-- --> <!-- -->hours of operation. Density functional theory calculations revealed that the Ru-Ru<sub>2</sub>P heterojunction could rearrange charge and modify the Ru <em>d</em>-band center, optimizing the adsorption energy of active ⁎H (|ΔG<sub>⁎H</sub>|) and breakage energy of ⁎H-OH bond (ΔG<sub>H2O</sub>).","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"15 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142690953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-23DOI: 10.1016/j.jallcom.2024.177732
P. Mahesh, S.S. Satheesh Kumar, I. Balasundar, C. Vanitha
Medium alloyed nickel-based superalloy DMR SN 742 is widely used as high-pressure compressor (HPC) and turbine (HPT) rotors in various aeroengines. Establishing innovative processing schemes is essential to improve the workability of this difficult-to-deform material. A combination of heterogenization and high temperature deformation has been employed in this study to address this issue. Heterogenization is intended to coarsen the gamma prime (γ′) phase present in the material while the deformation is intended to refine the size of gamma matrix. A combination of the aforementioned processes is expected to assist in producing fine grained equiaxed duplex microstructure comprising of gamma prime (γ′) and gamma (γ) that exhibits better workability. In order to identify and establish suitable heterogenization scheme for DMR SN 742, sub-solvus and super-solvus heterogenization was carried out by imposing a controlled cooling rate of 10 oC/hr after high temperature exposure. Detailed microstructural evaluation carried out on material subjected to heterogenization revealed multimodal distribution of γ′ precipitate within the parent gamma matrix. The coarsening of γ′ precipitates was observed to be significantly higher for super-solvus heterogenization when compared to sub-solvus heterogenization. Further, the high temperature deformation behaviour of sub and super solvus heterogenized material was investigated by carrying out isothermal hot compression test at 1000 oC with a constant true strain rate of 10-3 and 10-1/s. Heterogenized material were found to exhibit better workability when compared to the as-received material. Further, super solvus heterogenized material exhibited a relatively less flow stress, higher flow softening and higher discontinuous dynamic recrystallized grain fraction. A combination of super solvus heterogenization followed by deformation at 1000 oC with a strain rate of 10-1/sec can be used to coarsen the γ′ precipitate (primary: 1.2± 0.4 μm, secondary: 0.66 ± 0.19μm) and refine the size of gamma matrix (1-1.5μm) nickel based superalloy DMR SN 742.
{"title":"Effect of Heterogenization on the Microstructure Evolution and High Temperature Deformation Behaviour of a Nickel base Superalloy","authors":"P. Mahesh, S.S. Satheesh Kumar, I. Balasundar, C. Vanitha","doi":"10.1016/j.jallcom.2024.177732","DOIUrl":"https://doi.org/10.1016/j.jallcom.2024.177732","url":null,"abstract":"Medium alloyed nickel-based superalloy DMR SN 742 is widely used as high-pressure compressor (HPC) and turbine (HPT) rotors in various aeroengines. Establishing innovative processing schemes is essential to improve the workability of this difficult-to-deform material. A combination of heterogenization and high temperature deformation has been employed in this study to address this issue. Heterogenization is intended to coarsen the gamma prime (γ′) phase present in the material while the deformation is intended to refine the size of gamma matrix. A combination of the aforementioned processes is expected to assist in producing fine grained equiaxed duplex microstructure comprising of gamma prime (γ′) and gamma (γ) that exhibits better workability. In order to identify and establish suitable heterogenization scheme for DMR SN 742, sub-solvus and super-solvus heterogenization was carried out by imposing a controlled cooling rate of 10<!-- --> <sup>o</sup>C/hr after high temperature exposure. Detailed microstructural evaluation carried out on material subjected to heterogenization revealed multimodal distribution of γ′ precipitate within the parent gamma matrix. The coarsening of γ′ precipitates was observed to be significantly higher for super-solvus heterogenization when compared to sub-solvus heterogenization. Further, the high temperature deformation behaviour of sub and super solvus heterogenized material was investigated by carrying out isothermal hot compression test at 1000<!-- --> <sup>o</sup>C with a constant true strain rate of 10<sup>-3</sup> and 10<sup>-1</sup>/s. Heterogenized material were found to exhibit better workability when compared to the as-received material. Further, super solvus heterogenized material exhibited a relatively less flow stress, higher flow softening and higher discontinuous dynamic recrystallized grain fraction. A combination of super solvus heterogenization followed by deformation at 1000<!-- --> <sup>o</sup>C with a strain rate of 10<sup>-1</sup>/sec can be used to coarsen the γ′ precipitate (primary: 1.2± 0.4 μm, secondary: 0.66 ± 0.19μm) and refine the size of gamma matrix (1-1.5μm) nickel based superalloy DMR SN 742.","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"20 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142690954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The medium-entropy alloy Hf20Nb10Ti35Zr35 has a ductile BCC structure in the as-solution-treated state and could be age-hardening with fine precipitates. In this study, the thermal stress produced by thermal cycling was found to accelerate the precipitation of the α" and the evolution of ω → α phase of Hf20Nb10Ti35Zr35. The α''-martensite phase of Hf20Nb10Ti35Zr35 tended to grow in the (001)β plane, with the misorientation angle being concentrated around 52° after 10 thermal cycles. Moreover, the misorientation angle tended to have a bimodal distribution after 50 thermal cycles. Nanomechanical testing was performed to measure the strain rate sensitivity (SRS) at room temperature. The result shows that SRS of Hf20Nb10Ti35Zr35 changed from a small positive value of 0.09247 to a small negative one of either -0.02125 or -0.0445.This was mainly attributable to the decrease in the volume of the β phase or the increase of the α" + α composite phase. This demonstrates that thermal cycling treatment of the present alloy could induce more precipitation of second phase for hardening and enhance uniform deformation behavior.
{"title":"Microstructure evolution and strain rate sensitivity of ductile Hf20Nb10Ti35Zr35 medium-entropy alloy after thermal cycling","authors":"Shing-Hoa Wang, Chia-Heng Liu, Jien-Wei Yeh, Tzu-Ching Tsao, Chia-Lin Li, Horng-Yi Chang, Jer-Ren Yang, Chun-Hway Hsueh, Liu-Wen Chang, Xue-Qian Zheng, Yuan-Tzu Lee, Ya-Ching Yang","doi":"10.1016/j.jallcom.2024.177726","DOIUrl":"https://doi.org/10.1016/j.jallcom.2024.177726","url":null,"abstract":"The medium-entropy alloy Hf<sub>20</sub>Nb<sub>10</sub>Ti<sub>35</sub>Zr<sub>35</sub> has a ductile BCC structure in the as-solution-treated state and could be age-hardening with fine precipitates. In this study, the thermal stress produced by thermal cycling was found to accelerate the precipitation of the <em>α\"</em> and the evolution of <em>ω</em> → <em>α</em> phase of Hf<sub>20</sub>Nb<sub>10</sub>Ti<sub>35</sub>Zr<sub>35</sub>. The <em>α</em>''-martensite phase of Hf<sub>20</sub>Nb<sub>10</sub>Ti<sub>35</sub>Zr<sub>35</sub> tended to grow in the (001)<sub><em>β</em></sub> plane, with the misorientation angle being concentrated around 52° after 10 thermal cycles. Moreover, the misorientation angle tended to have a bimodal distribution after 50 thermal cycles. Nanomechanical testing was performed to measure the strain rate sensitivity (SRS) at room temperature. The result shows that SRS of Hf<sub>20</sub>Nb<sub>10</sub>Ti<sub>35</sub>Zr<sub>35</sub> changed from a small positive value of 0.09247 to a small negative one of either -0.02125 or -0.0445.This was mainly attributable to the decrease in the volume of the <em>β</em> phase or the increase of the <em>α\"</em> + <em>α</em> composite phase. This demonstrates that thermal cycling treatment of the present alloy could induce more precipitation of second phase for hardening and enhance uniform deformation behavior.","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"8 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142690949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ductile participation with small lattice misfit against matrix has been a long-sought-after character in toughening alloys, and recently multicomponent intermetallic nanoparticle L12 phase was explored by compositional modification in FeCoNi-based alloys and reported its benefits on strength and ductility through 780 °C for 4 h aging treatment. However, the L12 (A3B: Ni3Al) evolution in (FeCoNi)86-Al7Ti7 at a wide range of aging temperatures still lacks of comprehensive investigations. Herein, a series of aging temperatures (580 °C, 650 °C, 690 °C, 720 °C, 780 °C, and 820 °C) were carried out based on the synchrotron in-situ variable temperature XRD of the alloy. Results showed that both the composition and morphology of the L12 phase are dramatically dependent on the aging temperatures. Specifically, with aging temperature increased from 580 °C to 820 °C, A sites preferentially incorporated by more Co and Fe gradually turn into B sites partially substituted by Fe and Ti in the L12 phase, together with its morphology transforming from spherical to cuboidal. Meanwhile, the hierarchical microstructure induced by the precipitates of the tiny L12 phase at the aging temperature of 780 °C compensated the size departure of the primary L12 phase against the critical size to enhance the strength by enhancing its dislocation storage capacity. These hierarchical L12 phases strengthen the strong pair-coupling mechanism, ultimately illustrating its excellent strength-ductility balance aging at 780 °C against other aging temperatures.
与基体晶格错位小的韧性参与一直是增韧合金所追求的特性，最近通过成分改性在铁钴镍基合金中探索了多组分金属间纳米粒子 L12 相，并报道了其在 780 °C 4 小时时效处理中对强度和延展性的益处。然而，对于（FeCoNi）86-Al7Ti7 中的 L12（A3B：Ni3Al）在较宽的时效温度范围内的演化仍缺乏全面的研究。本文基于同步加速器原位变温 XRD 对合金进行了一系列老化温度（580 ℃、650 ℃、690 ℃、720 ℃、780 ℃ 和 820 ℃）的研究。结果表明，L12 相的成分和形态都与时效温度有很大关系。具体来说，随着时效温度从 580 ℃ 升高到 820 ℃，L12 相中由更多 Co 和铁优先结合的 A 位点逐渐转变为由铁和钛部分替代的 B 位点，其形态也从球形转变为立方体。同时，在 780 ℃ 的老化温度下，微小 L12 相的析出物所诱导的分层微观结构补偿了原生 L12 相的尺寸偏离临界尺寸的情况，从而通过提高其位错存储能力来增强强度。这些分层的 L12 相强化了强对偶机制，最终说明了在 780 °C 老化温度下与其他老化温度相比，该材料具有出色的强度-电导率平衡能力。
{"title":"Evolution of Ductile L12 Phase in (FeCoNi)86-Al7Ti7 High-Entropy Alloy Aging at Various Temperatures and Its Strengthening Mechanism","authors":"Chenlei Shen, Feng Jiang, Chenyu Xu, Mingqin Xu, Lisha Liu, Zhenni Zhou, Fangyuan Zhu, Jiaojiao Yi","doi":"10.1016/j.jallcom.2024.177729","DOIUrl":"https://doi.org/10.1016/j.jallcom.2024.177729","url":null,"abstract":"Ductile participation with small lattice misfit against matrix has been a long-sought-after character in toughening alloys, and recently multicomponent intermetallic nanoparticle L1<sub>2</sub> phase was explored by compositional modification in FeCoNi-based alloys and reported its benefits on strength and ductility through 780 °C for 4<!-- --> <!-- -->h aging treatment. However, the L1<sub>2</sub> (A<sub>3</sub>B: Ni<sub>3</sub>Al) evolution in (FeCoNi)<sub>86</sub>-Al<sub>7</sub>Ti<sub>7</sub> at a wide range of aging temperatures still lacks of comprehensive investigations. Herein, a series of aging temperatures (580 °C, 650 °C, 690 °C, 720 °C, 780 °C, and 820 °C) were carried out based on the synchrotron in-situ variable temperature XRD of the alloy. Results showed that both the composition and morphology of the L1<sub>2</sub> phase are dramatically dependent on the aging temperatures. Specifically, with aging temperature increased from 580 °C to 820 °C, A sites preferentially incorporated by more Co and Fe gradually turn into B sites partially substituted by Fe and Ti in the L1<sub>2</sub> phase, together with its morphology transforming from spherical to cuboidal. Meanwhile, the hierarchical microstructure induced by the precipitates of the tiny L1<sub>2</sub> phase at the aging temperature of 780 °C compensated the size departure of the primary L1<sub>2</sub> phase against the critical size to enhance the strength by enhancing its dislocation storage capacity. These hierarchical L1<sub>2</sub> phases strengthen the strong pair-coupling mechanism, ultimately illustrating its excellent strength-ductility balance aging at 780 °C against other aging temperatures.","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"13 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142690948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-23DOI: 10.1016/j.jallcom.2024.177727
Shuo Ma, Panmei Liu, Liming Yu, Yuan Huang, Zumin Wang
The structural order significantly influences the oxidation resistance of alloys, but its effect on oxidation behaviors in humid environments remains underexplored. Herein, a comprehensive investigation of the effect of structural order on the wet oxidation of alloys was conducted using amorphous and crystalline Zr-Cu-Al alloys as model systems. The amorphous Zr-Cu-Al alloy exhibits stronger resistance to wet oxidation than its crystalline counterpart, which can be ascribed to the higher activation barriers associated with dense and disordered atomic structures of amorphous (Zr, Al)-oxide and substrate. An amorphous Cu-rich structure is observed in the amorphous alloy, whereas internal oxidation occurs in the crystalline alloy with a resulting multilayered Cu-rich structure (i.e. intermetallic compounds). This study highlights the critical role of structural order in oxidation resistance, providing new insights into the design strategies of alloys served in humid environments.
{"title":"Comparative study of wet oxidation in amorphous and crystalline Zr-Cu-Al: The effect of structural order","authors":"Shuo Ma, Panmei Liu, Liming Yu, Yuan Huang, Zumin Wang","doi":"10.1016/j.jallcom.2024.177727","DOIUrl":"https://doi.org/10.1016/j.jallcom.2024.177727","url":null,"abstract":"The structural order significantly influences the oxidation resistance of alloys, but its effect on oxidation behaviors in humid environments remains underexplored. Herein, a comprehensive investigation of the effect of structural order on the wet oxidation of alloys was conducted using amorphous and crystalline Zr-Cu-Al alloys as model systems. The amorphous Zr-Cu-Al alloy exhibits stronger resistance to wet oxidation than its crystalline counterpart, which can be ascribed to the higher activation barriers associated with dense and disordered atomic structures of amorphous (Zr, Al)-oxide and substrate. An amorphous Cu-rich structure is observed in the amorphous alloy, whereas internal oxidation occurs in the crystalline alloy with a resulting multilayered Cu-rich structure (i.e. intermetallic compounds). This study highlights the critical role of structural order in oxidation resistance, providing new insights into the design strategies of alloys served in humid environments.","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"59 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142690952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-23DOI: 10.1016/j.jallcom.2024.177733
Panzhen Li, Zhe Huang, Jin Yang, Chenhe Zhang, Siwei Tang, Yunzhu Ma, Wensheng Liu
As an important interconnecting material for solar cells, photovoltaic silver paste is in high demand. The silver powder, used as the conductive phase, greatly influences the conductivity of the paste. In this study, microfluidic technology was employed to achieve rapid and uniform mixing at the molecular level and the influence of microfluidic process conditions and reaction rates on silver powder morphology was investigated. Particularly, microfluidic technology can prevent the heterogeneous nucleation on wall of container. Using a 1.5 mol/L ascorbic acid concentration, spherical silver powder measuring 0.70–0.80 μm was produced through the convection reaction of two microflows at a 10 mL/min flow rate. This silver powder exhibited better shape regularization compared to that produced by macromixing. When mixed with micron flake silver powder in a 1:1 mass ratio and sintered at 150℃ for 45 min, the microfluidically prepared silver powder achieved a resistivity of 2.72 × 10−5 Ω.cm. This work introduces a new approach for preparing submicron silver powder, which has important applications in the solar cell silver paste field.
{"title":"Container-Free Microfluidic Chemical Reduction for Synthesizing Ultrafine Silver Powder and Fabricating Silver Paste","authors":"Panzhen Li, Zhe Huang, Jin Yang, Chenhe Zhang, Siwei Tang, Yunzhu Ma, Wensheng Liu","doi":"10.1016/j.jallcom.2024.177733","DOIUrl":"https://doi.org/10.1016/j.jallcom.2024.177733","url":null,"abstract":"As an important interconnecting material for solar cells, photovoltaic silver paste is in high demand. The silver powder, used as the conductive phase, greatly influences the conductivity of the paste. In this study, microfluidic technology was employed to achieve rapid and uniform mixing at the molecular level and the influence of microfluidic process conditions and reaction rates on silver powder morphology was investigated. Particularly, microfluidic technology can prevent the heterogeneous nucleation on wall of container. Using a 1.5<!-- --> <!-- -->mol/L ascorbic acid concentration, spherical silver powder measuring 0.70–0.80 μm was produced through the convection reaction of two microflows at a 10<!-- --> <!-- -->mL/min flow rate. This silver powder exhibited better shape regularization compared to that produced by macromixing. When mixed with micron flake silver powder in a 1:1 mass ratio and sintered at 150℃ for 45<!-- --> <!-- -->min, the microfluidically prepared silver powder achieved a resistivity of 2.72 × 10<sup>−5</sup> Ω.cm. This work introduces a new approach for preparing submicron silver powder, which has important applications in the solar cell silver paste field.","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"24 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142690951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-22DOI: 10.1016/j.jallcom.2024.177719
Chao Ma, Teng Su, Zhuohang Li, Bei Ren, Ziqian Meng, Bo Li, Ruixin Hao, Yang Miao, Feng Gao
Development of microwave dielectric ceramics with a high dielectric constant, high quality factor, and low temperature coefficient of resonant frequency is of great importance for achieving miniaturization, low loss, and high stability in microwave devices. Research on low dielectric constant microwave dielectric ceramics has made certain progress, but the development of new systems of high dielectric constant microwave dielectric ceramics with excellent overall performance is still in the exploratory stage. Herein, approaches of high-entropy strategy and small radius ions doping were combined to achieve high microwave dielectric properties. It is demonstrated that a high-entropy ceramic with a perovskite structure doped with Al3+ ion, denoted as (Ba0.25Ca0.25Sr0.25La0.25)Ti1-xAlxO3 (abbreviated as HESOs, 0<x≤0.25), was successfully synthesized. At x=0.1 and 1500 oC, HESO exhibited optimized comprehensive dielectric performance, characterized by εr = 89.25, Q×f = 3304 GHz, and τf = +361 ppm/oC. Besides, as the aluminum ion content increases, there is a reduction in grain size accompanied by an elevation in oxygen vacancy content, resulting in increase of Q×f, with a peak value reaching 4136 GHz. This study presents a valuable exploration aimed at designing high-entropy perovskite ceramics with excellent dielectric properties.
{"title":"Preparation of (Ba0.25Ca0.25Sr0.25La0.25)Ti1-xAlxO3 High-Entropy Perovskite Ceramics for enhanced Microwave Dielectric Performance","authors":"Chao Ma, Teng Su, Zhuohang Li, Bei Ren, Ziqian Meng, Bo Li, Ruixin Hao, Yang Miao, Feng Gao","doi":"10.1016/j.jallcom.2024.177719","DOIUrl":"https://doi.org/10.1016/j.jallcom.2024.177719","url":null,"abstract":"Development of microwave dielectric ceramics with a high dielectric constant, high quality factor, and low temperature coefficient of resonant frequency is of great importance for achieving miniaturization, low loss, and high stability in microwave devices. Research on low dielectric constant microwave dielectric ceramics has made certain progress, but the development of new systems of high dielectric constant microwave dielectric ceramics with excellent overall performance is still in the exploratory stage. Herein, approaches of high-entropy strategy and small radius ions doping were combined to achieve high microwave dielectric properties. It is demonstrated that a high-entropy ceramic with a perovskite structure doped with Al<sup>3+</sup> ion, denoted as (Ba<sub>0.25</sub>Ca<sub>0.25</sub>Sr<sub>0.25</sub>La<sub>0.25</sub>)Ti<sub>1-x</sub>Al<sub>x</sub>O<sub>3</sub> (abbreviated as HESOs, 0<<em>x</em>≤0.25), was successfully synthesized. At <em>x</em>=0.1 and 1500<!-- --> <sup>o</sup>C, HESO exhibited optimized comprehensive dielectric performance, characterized by <em>ε</em><sub><em>r</em></sub> = 89.25, <em>Q</em>×<em>f</em> = 3304<!-- --> <!-- -->GHz, and <em>τ</em><sub><em>f</em></sub> = +361 ppm<sub>/</sub><sup>o</sup>C. Besides, as the aluminum ion content increases, there is a reduction in grain size accompanied by an elevation in oxygen vacancy content, resulting in increase of <em>Q</em>×<em>f</em>, with a peak value reaching 4136<!-- --> <!-- -->GHz. This study presents a valuable exploration aimed at designing high-entropy perovskite ceramics with excellent dielectric properties.","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"310 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142684679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-22DOI: 10.1016/j.jallcom.2024.177709
Hongyuan Song, Yijia Pang, Linjie Dong, Kun Dong, Haorong Wu, Liangwei Chen, Bin Liu, Zhenhua Ge, Lan Yu
Transition metal oxides are considered ideal electrocatalyst materials due to their low cost and high intrinsic activity. Among them, SrCoO3-δ has received increasing attention due to its multi-phase structure and tunable electronic properties, though its OER reaction kinetics and catalysis stability are unsatisfactory. Herein, based on a simple one-step solid-state reaction method, we use a small amount of rare earth Y ions (10%) to transform H-SCO2.52 from a hexagonal structure to a stable cubic perovskite Sr0.9Y0.1CoO3−δ. While broadening the atomic ratio of Co and Fe in the B-site under the cubic perovskite Sr0.9Y0.1Co1-xFexO3−δ (x = 0~1), the relationship between the B-site electronic state, oxygen vacancies, and OER performance has been explored. Sr0.9Y0.1Co0.2Fe0.8O3−δ with a high concentration of oxygen vacancies, exhibits the lowest overpotential of 277 mV and maintains stability at 10 mA cm-2 for 88 hours. The valence states of Fe and Co atoms in SYC0.2F0.8 O are optimized (Fe2+~50.81%, Co2+~19.39%), and the oxygen evolution activity is enhanced by electrochemical reconfiguration to form high-valence Fe and Co ions. Selective leaching of Sr ions via electrochemical surface reconstruction activates FeOOH and CoOOH amorphous layer active sites on the catalyst surface, significantly enhancing reaction kinetics.
过渡金属氧化物因其低成本和高内在活性而被认为是理想的电催化剂材料。其中，SrCoO3-δ因其多相结构和可调的电子特性受到越来越多的关注，但其OER反应动力学和催化稳定性并不理想。在此，我们基于简单的一步固态反应方法，利用少量稀土 Y 离子（10%）将 H-SCO2.52 从六方结构转变为稳定的立方包晶 Sr0.9Y0.1CoO3-δ。在拓宽立方包晶 Sr0.9Y0.1Co1-xFexO3-δ（x = 0~1）B 位中 Co 和 Fe 原子比例的同时，还探讨了 B 位电子状态、氧空位和 OER 性能之间的关系。氧空位浓度较高的 Sr0.9Y0.1Co0.2Fe0.8O3-δ 显示出 277 mV 的最低过电位，并能在 10 mA cm-2 下保持稳定 88 小时。SYC0.2F0.8 O 中铁原子和钴原子的价态得到优化（Fe2+~50.81%，Co2+~19.39%），通过电化学重构形成高价态的铁离子和钴离子，提高了氧进化活性。通过电化学表面重构选择性浸出 Sr 离子激活了催化剂表面的 FeOOH 和 CoOOH 非晶层活性位点，显著提高了反应动力学。
{"title":"High stability cubic perovskite Sr0.9Y0.1Co1-xFexO3-δ oxygen evolution by phase control and electrochemical reconstruction","authors":"Hongyuan Song, Yijia Pang, Linjie Dong, Kun Dong, Haorong Wu, Liangwei Chen, Bin Liu, Zhenhua Ge, Lan Yu","doi":"10.1016/j.jallcom.2024.177709","DOIUrl":"https://doi.org/10.1016/j.jallcom.2024.177709","url":null,"abstract":"Transition metal oxides are considered ideal electrocatalyst materials due to their low cost and high intrinsic activity. Among them, SrCoO<sub>3-<em>δ</em></sub> has received increasing attention due to its multi-phase structure and tunable electronic properties, though its OER reaction kinetics and catalysis stability are unsatisfactory. Herein, based on a simple one-step solid-state reaction method, we use a small amount of rare earth Y ions (10%) to transform H-SCO<sub>2.52</sub> from a hexagonal structure to a stable cubic perovskite Sr<sub>0.9</sub>Y<sub>0.1</sub>CoO<sub>3−<em>δ</em></sub>. While broadening the atomic ratio of Co and Fe in the B-site under the cubic perovskite Sr<sub>0.9</sub>Y<sub>0.1</sub>Co<sub>1-<em>x</em></sub>Fe<sub><em>x</em></sub>O<sub>3−<em>δ</em></sub> (<em>x</em> = 0~1), the relationship between the B-site electronic state, oxygen vacancies, and OER performance has been explored. Sr<sub>0.9</sub>Y<sub>0.1</sub>Co<sub>0.2</sub>Fe<sub>0.8</sub>O<sub>3−<em>δ</em></sub> with a high concentration of oxygen vacancies, exhibits the lowest overpotential of 277<!-- --> <!-- -->mV and maintains stability at 10<!-- --> <!-- -->mA<!-- --> <!-- -->cm<sup>-2</sup> for 88<!-- --> <!-- -->hours. The valence states of Fe and Co atoms in SYC0.2F0.8<!-- --> <!-- -->O are optimized (Fe<sup>2+</sup>~50.81%, Co<sup>2+</sup>~19.39%), and the oxygen evolution activity is enhanced by electrochemical reconfiguration to form high-valence Fe and Co ions. Selective leaching of Sr ions via electrochemical surface reconstruction activates FeOOH and CoOOH amorphous layer active sites on the catalyst surface, significantly enhancing reaction kinetics.","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"18 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142684686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The TiO2 doped CaNb2O6 ceramics were successfully prepared by solid state reaction in this work. The XRD and Rietveld refinement results of the CaNb2-xTixO6 (0≤x≤0.025) showed that Ti4+ entered the Nb5+ lattice site and replaced a part of Nb5+, forming a substitutional solid solution. The XPS results of the CaNb2-xTixO6 ceramics explained that Ti4+ entered the Nb5+ lattice position and caused the formation of oxygen vacancies. Dipoles caused by oxygen vacancies limited the long-range transition of electrons, resulting in electron pinning effect. The SEM results displayed that with the addition of Ti4+, the structure of CaNb2-xTixO6 ceramics densified rapidly. The dielectric constant (εr), resonant frequency (τf) and quality factor (Q×f) values were related to density, bond valence, anharmonic motion between atoms and crystallinity, respectively, which provided a theoretical basis for further regulating microwave dielectric properties. When the doping amount of Ti4+ increased from 0.005 to 0.02, the τf value increased from -62ppm/°C to -22ppm/°C. The CaNb2-xTixO6 ceramics with x=0.02 sintered at 1425 °C for 4 h had excellent microwave dielectric properties: εr = 15.76, Q×f =30397 GHz, τf =-22 ppm/°C.
{"title":"Effect of TiO2 doping on microstructure and microwave dielectric properties of CaNb2O6 ceramics","authors":"Zehui Lin, Yuanming Lai, Menghong Li, Jiaqi He, Mingwei Li, Ju Zhou, Shiqi Li, Wenhan Qi, Jiao Han, Yiming Zeng","doi":"10.1016/j.jallcom.2024.177717","DOIUrl":"https://doi.org/10.1016/j.jallcom.2024.177717","url":null,"abstract":"The TiO<sub>2</sub> doped CaNb<sub>2</sub>O<sub>6</sub> ceramics were successfully prepared by solid state reaction in this work. The XRD and Rietveld refinement results of the CaNb<sub>2-x</sub>Ti<sub>x</sub>O<sub>6</sub> (0≤x≤0.025) showed that Ti<sup>4+</sup> entered the Nb<sup>5+</sup> lattice site and replaced a part of Nb<sup>5+</sup>, forming a substitutional solid solution. The XPS results of the CaNb<sub>2-x</sub>Ti<sub>x</sub>O<sub>6</sub> ceramics explained that Ti<sup>4+</sup> entered the Nb<sup>5+</sup> lattice position and caused the formation of oxygen vacancies. Dipoles caused by oxygen vacancies limited the long-range transition of electrons, resulting in electron pinning effect. The SEM results displayed that with the addition of Ti<sup>4+</sup>, the structure of CaNb<sub>2-x</sub>Ti<sub>x</sub>O<sub>6</sub> ceramics densified rapidly. The dielectric constant (ε<sub>r</sub>), resonant frequency (τ<sub>f</sub>) and quality factor (Q×f) values were related to density, bond valence, anharmonic motion between atoms and crystallinity, respectively, which provided a theoretical basis for further regulating microwave dielectric properties. When the doping amount of Ti<sup>4+</sup> increased from 0.005 to 0.02, the τ<sub>f</sub> value increased from -62ppm/°C to -22ppm/°C. The CaNb<sub>2-x</sub>Ti<sub>x</sub>O<sub>6</sub> ceramics with x=0.02 sintered at 1425 °C for 4<!-- --> <!-- -->h had excellent microwave dielectric properties: ε<sub>r</sub> = 15.76, Q×f =30397<!-- --> <!-- -->GHz, τ<sub>f</sub> =-22 ppm/°C.","PeriodicalId":344,"journal":{"name":"Journal of Alloys and Compounds","volume":"4 1","pages":""},"PeriodicalIF":6.2,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142684682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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