Pub Date : 2026-08-01Epub Date: 2026-02-09DOI: 10.1016/j.jeurceramsoc.2026.118224
Wei Ning , Xinxin Cao , Guifang Han , Egor Borisovich Kashkarov , Nahum Travitzky
This study explores the regulation of grain growth and sintering mechanism of self-toughening Si3N4 simply by controlling the amount of CaF2 added. CaF2 was transformed into CaO in-situ via its reaction with SiO2 on the surface of Si3N4. This simultaneously achieved three effects: inhibiting the secondary phase CaSiO3 generated easily by direct addition of CaO; in-situ generated CaO regulates the grain growth and densification of Si3N4 with high aspect ratio; formation of CaF2-CaO low viscosity liquid phase facilitates sintering and densification process. All these can be achieved by adjusting the amount of CaF2. The reaction mechanism of CaF2 as a novel sintering additive in Si3N4 ceramics was explored for the first time through thermodynamic theoretical calculation and phase diagram. This work provides a new combination method for the design and development of easy-to-control, efficient and cost-effective sintering additives for Si3N4 and other high temperature ceramics.
{"title":"Regulating grain growth and sintering mechanism of Si3N4 ceramics: Three effects achieved simultaneously by controlling the amount of CaF2 additive","authors":"Wei Ning , Xinxin Cao , Guifang Han , Egor Borisovich Kashkarov , Nahum Travitzky","doi":"10.1016/j.jeurceramsoc.2026.118224","DOIUrl":"10.1016/j.jeurceramsoc.2026.118224","url":null,"abstract":"<div><div>This study explores the regulation of grain growth and sintering mechanism of self-toughening Si<sub>3</sub>N<sub>4</sub> simply by controlling the amount of CaF<sub>2</sub> added. CaF<sub>2</sub> was transformed into CaO <em>in-situ</em> via its reaction with SiO<sub>2</sub> on the surface of Si<sub>3</sub>N<sub>4</sub>. This simultaneously achieved three effects: inhibiting the secondary phase CaSiO<sub>3</sub> generated easily by direct addition of CaO; <em>in-situ</em> generated CaO regulates the grain growth and densification of Si<sub>3</sub>N<sub>4</sub> with high aspect ratio; formation of CaF<sub>2</sub>-CaO low viscosity liquid phase facilitates sintering and densification process. All these can be achieved by adjusting the amount of CaF<sub>2</sub>. The reaction mechanism of CaF<sub>2</sub> as a novel sintering additive in Si<sub>3</sub>N<sub>4</sub> ceramics was explored for the first time through thermodynamic theoretical calculation and phase diagram. This work provides a new combination method for the design and development of easy-to-control, efficient and cost-effective sintering additives for Si<sub>3</sub>N<sub>4</sub> and other high temperature ceramics.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 9","pages":"Article 118224"},"PeriodicalIF":6.2,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191590","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 : 2026-08-01Epub Date: 2026-01-29DOI: 10.1016/j.jeurceramsoc.2026.118188
Youle Liu , Yufeng Zhang , Yucheng Zhang , Hongkun Li , Jianqiu Zhu , Ze Liu , Peng Du , Xiao Lin , Jian Qiang Wang , Linjuan Zhang
Protonic ceramic fuel cells (PCFCs) are promising energy conversion devices but often degrade due to Ni agglomeration at elevated temperatures. Here, we report an interface-engineering strategy by incorporating optimized ceria (CeO2, 7.5 wt%) into the Ni–BZCYYb anode functional layer via scalable tape casting. The CeO2-modified cell delivers a peak power density of 1.427 W cm−2 at 650 °C, a 10.19 % improvement over the reference. Under galvanostatic operation at 1 A cm−2, the voltage decay is only 2.87 % after 400 h, compared with 7.72 % for the reference. EIS and FIB-SEM quantification show suppressed Ni coarsening with a finer microstructure and higher TPB density. The results support a dual-stage contribution of CeO2 to stabilization during sintering and long-term operation, with atomistic insights further supported by reported DFT/KMC literature. This work presents a feasible industrial strategy to significantly enhance both performance and durability of proton-conducting ceramic cells through targeted interfacial modification.
质子陶瓷燃料电池（pcfc）是一种很有前途的能量转换器件，但由于高温下镍的聚集，质子陶瓷燃料电池往往会退化。在这里，我们报告了一种界面工程策略，通过可扩展的带铸造将优化的铈（CeO2, 7.5 wt%）纳入Ni-BZCYYb阳极功能层。在650°C时，ceo2修饰电池的峰值功率密度为1.427 W cm−2，比参考电池提高10.19 %。在1 A cm−2的恒流操作下，400 h后电压衰减仅为2.87 %，而参考电压衰减为7.72 %。EIS和FIB-SEM量化表明，Ni粗化受到抑制，其微观结构更细，TPB密度更高。研究结果支持了CeO2在烧结和长期运行过程中对稳定的双阶段贡献，并得到了DFT/KMC文献的进一步支持。本研究提出了一种可行的工业策略，通过有针对性的界面修饰来显著提高质子导电陶瓷电池的性能和耐久性。
{"title":"Microstructural and electrochemical stabilization of protonic ceramic cells by ceria interface engineering","authors":"Youle Liu , Yufeng Zhang , Yucheng Zhang , Hongkun Li , Jianqiu Zhu , Ze Liu , Peng Du , Xiao Lin , Jian Qiang Wang , Linjuan Zhang","doi":"10.1016/j.jeurceramsoc.2026.118188","DOIUrl":"10.1016/j.jeurceramsoc.2026.118188","url":null,"abstract":"<div><div>Protonic ceramic fuel cells (PCFCs) are promising energy conversion devices but often degrade due to Ni agglomeration at elevated temperatures. Here, we report an interface-engineering strategy by incorporating optimized ceria (CeO<sub>2</sub>, 7.5 wt%) into the Ni–BZCYYb anode functional layer via scalable tape casting. The CeO2-modified cell delivers a peak power density of 1.427 W cm<sup>−2</sup> at 650 °C, a 10.19 % improvement over the reference. Under galvanostatic operation at 1 A cm<sup>−2</sup>, the voltage decay is only 2.87 % after 400 h, compared with 7.72 % for the reference. EIS and FIB-SEM quantification show suppressed Ni coarsening with a finer microstructure and higher TPB density. The results support a dual-stage contribution of CeO<sub>2</sub> to stabilization during sintering and long-term operation, with atomistic insights further supported by reported DFT/KMC literature. This work presents a feasible industrial strategy to significantly enhance both performance and durability of proton-conducting ceramic cells through targeted interfacial modification.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 9","pages":"Article 118188"},"PeriodicalIF":6.2,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191684","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 : 2026-08-01Epub Date: 2026-01-30DOI: 10.1016/j.ijrmhm.2026.107711
Tao He , Feng-lin Zhang , Wei-jian Yang , Xin zhou , Xiao-yi Pan , Yu-mei Zhou
Dry grinding of hard and brittle materials has received increasing attention due to the environmental issues associated with using coolants and the need for machine tooling under dry conditions. However, during dry grinding, the high grinding temperature may induce thermal deformation of traditional metal bonds and accelerate the wear of diamond tools. In the present study, a refractory high-entropy alloy (RHEA) was introduced into Fe alloy to serve as the metal bond of diamond tool in order to improve the dry grinding performance. First, RHEA powders (composed of WMoTaNbV) were prepared by discharge plasma ball milling (DPBM) as well as planetary milling (PM) for comparison. The effect of ball milling time on the microstructure of RHEA powder was examined. Then, RHEA/Fe alloy was prepared by hot-press sintering, and the microstructures, mechanical properties and wear resistance of sintered RHEA/Fe alloys with different contents of RHEA were investigated. Finally, a RHEA/Fe alloy bond diamond tool was prepared to evaluate the dry grinding performance on a silicon nitride ceramic. The results indicated that RHEA powder was successfully synthesized by DPBM milling for only 15 h, which was a much shorter duration compared to PM method. With increasing RHEA content in the range of 0-20 wt%, the relative density of RHEA/Fe alloys decreased, but the hardness, compressive strength, and wear resistance increased. Good bonding was achieved between 20wt.%RHEA/Fe alloy and diamond grits in the synthesized diamond tool at the sintering temperature of 1050 °C. During dry grinding of silicon nitride ceramic, the diamond tool based on 20wt.%RHEA/Fe bond exhibited a lower grinding force, higher grinding ratio, and reduced wear in comparison with commercial Fe alloy bond diamond tool, showing excellent potential for the dry grinding of ceramics.
{"title":"Preparation of RHEA/Fe alloy bond diamond tools for dry grinding of silicon nitride","authors":"Tao He , Feng-lin Zhang , Wei-jian Yang , Xin zhou , Xiao-yi Pan , Yu-mei Zhou","doi":"10.1016/j.ijrmhm.2026.107711","DOIUrl":"10.1016/j.ijrmhm.2026.107711","url":null,"abstract":"<div><div>Dry grinding of hard and brittle materials has received increasing attention due to the environmental issues associated with using coolants and the need for machine tooling under dry conditions. However, during dry grinding, the high grinding temperature may induce thermal deformation of traditional metal bonds and accelerate the wear of diamond tools. In the present study, a refractory high-entropy alloy (RHEA) was introduced into Fe alloy to serve as the metal bond of diamond tool in order to improve the dry grinding performance. First, RHEA powders (composed of WMoTaNbV) were prepared by discharge plasma ball milling (DPBM) as well as planetary milling (PM) for comparison. The effect of ball milling time on the microstructure of RHEA powder was examined. Then, RHEA/Fe alloy was prepared by hot-press sintering, and the microstructures, mechanical properties and wear resistance of sintered RHEA/Fe alloys with different contents of RHEA were investigated. Finally, a RHEA/Fe alloy bond diamond tool was prepared to evaluate the dry grinding performance on a silicon nitride ceramic. The results indicated that RHEA powder was successfully synthesized by DPBM milling for only 15 h, which was a much shorter duration compared to PM method. With increasing RHEA content in the range of 0-20 wt%, the relative density of RHEA/Fe alloys decreased, but the hardness, compressive strength, and wear resistance increased. Good bonding was achieved between 20wt.%RHEA/Fe alloy and diamond grits in the synthesized diamond tool at the sintering temperature of 1050 °C. During dry grinding of silicon nitride ceramic, the diamond tool based on 20wt.%RHEA/Fe bond exhibited a lower grinding force, higher grinding ratio, and reduced wear in comparison with commercial Fe alloy bond diamond tool, showing excellent potential for the dry grinding of ceramics.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"138 ","pages":"Article 107711"},"PeriodicalIF":4.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146089225","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 : 2026-08-01Epub Date: 2026-01-26DOI: 10.1016/j.ijrmhm.2026.107689
Lizhi Xu , Mingyang Wang , Xuan Zhou , Zhanxuan Wang , Jun He , Yongkang Zhou , Zhengkun Li , Zhonghua Du
Tungsten fiber-reinforced bulk metallic glass composites (BMGCs) are high-strength, high-density materials with exceptional penetration capabilities, post-target fragmentation, and energy-release damage effects, making them highly valuable in defense applications. This study investigates a Zr-based BMGC (composition: Zr40.08Ti13.30Cu11.84Ni0.07Nb24.7) with a density of 12 g/cm3. Quasi-static/dynamic compression tests and ballistic experiments were conducted to systematically analyze its mechanical properties under varying strain rates and post-penetration fragmentation and damage effects. Results indicate that BMGCs exhibit high strength (ultimate strength of 1656 MPa) and plastic deformation under quasi-static loading, while dynamic loading induces brittle fracture and strain-rate softening (strength reduced to ∼1120 MPa at 1508 s−1). Ballistic tests reveal that BMGCs form a fragmented cloud after penetrating steel targets. Within the velocity range of 864–1407 m/s, the post-target damage mode transitions from shear plugging to tensile-dominated “petal” failure. The post-target damage area initially increases and decreases with velocity, peaking at 1325 m/s. Fragment size analysis shows that higher velocities increase the proportion of small fragments and their dispersion area, reducing the kinetic energy density per unit area and diminishing damage efficiency.
{"title":"Experimental investigation on rear-side fragmentation and damage of steel targets penetrated by tungsten fiber-reinforced bulk metallic glass composites","authors":"Lizhi Xu , Mingyang Wang , Xuan Zhou , Zhanxuan Wang , Jun He , Yongkang Zhou , Zhengkun Li , Zhonghua Du","doi":"10.1016/j.ijrmhm.2026.107689","DOIUrl":"10.1016/j.ijrmhm.2026.107689","url":null,"abstract":"<div><div>Tungsten fiber-reinforced bulk metallic glass composites (BMGCs) are high-strength, high-density materials with exceptional penetration capabilities, post-target fragmentation, and energy-release damage effects, making them highly valuable in defense applications. This study investigates a Zr-based BMGC (composition: Zr<sub>40.08</sub>Ti<sub>13.30</sub>Cu<sub>11.84</sub>Ni<sub>0.07</sub>Nb<sub>24.7</sub>) with a density of 12 g/cm<sup>3</sup>. Quasi-static/dynamic compression tests and ballistic experiments were conducted to systematically analyze its mechanical properties under varying strain rates and post-penetration fragmentation and damage effects. Results indicate that BMGCs exhibit high strength (ultimate strength of 1656 MPa) and plastic deformation under quasi-static loading, while dynamic loading induces brittle fracture and strain-rate softening (strength reduced to ∼1120 MPa at 1508 s<sup>−1</sup>). Ballistic tests reveal that BMGCs form a fragmented cloud after penetrating steel targets. Within the velocity range of 864–1407 m/s, the post-target damage mode transitions from shear plugging to tensile-dominated “petal” failure. The post-target damage area initially increases and decreases with velocity, peaking at 1325 m/s. Fragment size analysis shows that higher velocities increase the proportion of small fragments and their dispersion area, reducing the kinetic energy density per unit area and diminishing damage efficiency.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"138 ","pages":"Article 107689"},"PeriodicalIF":4.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146047860","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 : 2026-08-01Epub Date: 2026-01-23DOI: 10.1016/j.ijrmhm.2026.107683
Ziyi Zhao , Jin Du , Guosheng Su , Peirong Zhang , Binxun Li , Yujing Sun , Chonghai Xu
Cemented carbide is a typical difficult-to-machine material used in machine tool components. The grinding process is an effective method for achieving the desired shape and dimensional accuracy of cemented carbide parts. The deformation mechanisms and damage behavior of the ground surface depend on the grinding parameters. In this study, WC–Al₀.₅CoCrFeNi high-entropy cemented carbide (WC-HEA) was fabricated via vacuum gas-pressure composite sintering. Grinding experiments were conducted to analyze the phase composition, microstructure, deformation mechanisms, and damage behavior of the ground surface. A refined surface layer composed of both amorphous and nanocrystalline phases formed on the machined surface. The dominant damage behavior of WC grains within the refinement layer was fracture and microcracking. The severity of brittle damage and binder-phase deformation on the ground surface increased with grinding depth and feed rate. Under a high grinding strain rate, grain pull-out, brittle fragmentation, and cracking were reduced. Therefore, the surface exhibited lower roughness and fewer brittle damage defects. In addition, elevated strain rates promoted a deformation mechanism in the Al0.5CoCrFeNi binder phase, characterized by twinning and solid-state amorphization. This plastic deformation mechanism suppresses phase transformation defects. The findings of this study clarify the deformation mechanisms and damage behavior of WC-HEA under various grinding parameters, providing a theoretical basis for the efficient and high-quality processing of WC-HEA.
{"title":"Surface deformation and damage evolution mechanism in grinding of WC-Al0.5CoCrFeNi high-entropy cemented carbide","authors":"Ziyi Zhao , Jin Du , Guosheng Su , Peirong Zhang , Binxun Li , Yujing Sun , Chonghai Xu","doi":"10.1016/j.ijrmhm.2026.107683","DOIUrl":"10.1016/j.ijrmhm.2026.107683","url":null,"abstract":"<div><div>Cemented carbide is a typical difficult-to-machine material used in machine tool components. The grinding process is an effective method for achieving the desired shape and dimensional accuracy of cemented carbide parts. The deformation mechanisms and damage behavior of the ground surface depend on the grinding parameters. In this study, WC–Al₀.₅CoCrFeNi high-entropy cemented carbide (WC-HEA) was fabricated via vacuum gas-pressure composite sintering. Grinding experiments were conducted to analyze the phase composition, microstructure, deformation mechanisms, and damage behavior of the ground surface. A refined surface layer composed of both amorphous and nanocrystalline phases formed on the machined surface. The dominant damage behavior of WC grains within the refinement layer was fracture and microcracking. The severity of brittle damage and binder-phase deformation on the ground surface increased with grinding depth and feed rate. Under a high grinding strain rate, grain pull-out, brittle fragmentation, and cracking were reduced. Therefore, the surface exhibited lower roughness and fewer brittle damage defects. In addition, elevated strain rates promoted a deformation mechanism in the Al<sub>0.5</sub>CoCrFeNi binder phase, characterized by twinning and solid-state amorphization. This plastic deformation mechanism suppresses phase transformation defects. The findings of this study clarify the deformation mechanisms and damage behavior of WC-HEA under various grinding parameters, providing a theoretical basis for the efficient and high-quality processing of WC-HEA.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"138 ","pages":"Article 107683"},"PeriodicalIF":4.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146032910","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 microstructural evolution of wrought Tantalum - 2.5 wt% Tungsten (Ta-2.5W) alloys during thermomechanical processing is critical for optimizing their mechanical reliability in demanding applications such as aerospace, chemical processing, and nuclear technology. Despite the widespread use of Ta-W alloys, a comprehensive understanding of how rolling reduction, annealing temperature, and elemental inhomogeneity interact to determine recrystallization behavior and grain refinement remains incomplete. In this study, we systematically investigate the effects of cold rolling and subsequent annealing on the microstructure of Ta-2.5W, with particular attention to grain orientation, stored energy, and elemental banding. Our results demonstrate that higher rolling reduction rates lower the onset and completion temperatures for recrystallization, resulting in finer and more homogeneous grain structures. Electron backscatter diffraction (EBSD) analysis reveals that grains with a 〈111〉 parallel to the plate normal possess higher stored energy and nucleate recrystallization more readily than grains with a 〈001〉 parallel to the plate normal. Elemental mapping shows that tungsten inhomogeneity leads to localized bands of accelerated recrystallization and hardness variation. These findings provide new insights into the mechanisms of microstructure refinement in Ta-2.5W alloys, offering guidance for tailoring processing routes to achieve superior performance in demanding engineering environments.
{"title":"Influence of rolling reduction and annealing on recrystallization and grain structure in Ta-2.5W alloys","authors":"P.D. Paradise, R.P. Sankaran, M. Koelle, J.R. Boro, J.T. McKeown, T.Y. Han, S.R. Qiu","doi":"10.1016/j.ijrmhm.2026.107708","DOIUrl":"10.1016/j.ijrmhm.2026.107708","url":null,"abstract":"<div><div>The microstructural evolution of wrought Tantalum - 2.5 wt% Tungsten (Ta-2.5W) alloys during thermomechanical processing is critical for optimizing their mechanical reliability in demanding applications such as aerospace, chemical processing, and nuclear technology. Despite the widespread use of Ta-W alloys, a comprehensive understanding of how rolling reduction, annealing temperature, and elemental inhomogeneity interact to determine recrystallization behavior and grain refinement remains incomplete. In this study, we systematically investigate the effects of cold rolling and subsequent annealing on the microstructure of Ta-2.5W, with particular attention to grain orientation, stored energy, and elemental banding. Our results demonstrate that higher rolling reduction rates lower the onset and completion temperatures for recrystallization, resulting in finer and more homogeneous grain structures. Electron backscatter diffraction (EBSD) analysis reveals that grains with a 〈111〉 parallel to the plate normal possess higher stored energy and nucleate recrystallization more readily than grains with a 〈001〉 parallel to the plate normal. Elemental mapping shows that tungsten inhomogeneity leads to localized bands of accelerated recrystallization and hardness variation. These findings provide new insights into the mechanisms of microstructure refinement in Ta-2.5W alloys, offering guidance for tailoring processing routes to achieve superior performance in demanding engineering environments.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"138 ","pages":"Article 107708"},"PeriodicalIF":4.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146071503","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 : 2026-08-01Epub Date: 2026-02-09DOI: 10.1016/j.ijrmhm.2026.107728
Shuang Lin , Shun-Li Shang , Allison M. Beese , Zi-Kui Liu
In the present work, the density functional theory (DFT) in the generalized-gradient approximation developed by Perdew, Burke, and Ernzerhof (PBE) + U method, i.e., PBE + U, was employed to predict temperature-dependent thermodynamic properties of the rutile-type oxides CrNbO4 and CrTaO4 as well as the binary oxides Cr2O3, Nb2O5, and Ta2O5 via the quasiharmonic phonon approach (QHA). Calculated thermodynamic properties of the binary oxides were benchmarked with experimental data, showing high accuracy except for the negative thermal expansion (NTE) of Nb2O5, attributed to its polymorphic complexity. By combining the formation energy predicted by DFT with the existing SGTE Substances Database (SSUB5), the CrNbO4 and CrTaO4 are found to be thermodynamic stable up to 1706 K and 1926 K and decompose into Cr2O3 and Nb2O5 or Ta2O5 at those temperatures, respectively. The temperature dependence of linear thermal expansion coefficients for CrNbO4 and CrTaO4 are predicted, and their mean values from 500 K to 2000 K are found to be 6.0 × 10−6/K and 5.04 × 10−6/K, respectively, in agreement with experimental observations in the literature. The gas-phase species and their vapor pressure are calculated, indicating that the formation of CrTaO4 and CrNbO4 reduces chromium volatilization, which is critically important to design enhanced refractory high entropy alloys (RHEAs) with enhanced oxidation resistance.
本文利用Perdew， Burke, and Ernzerhof （PBE） + U方法中的密度泛函理论（DFT），即PBE + U，通过准谐波声子方法（QHA）预测了金红石型氧化物CrNbO4和CrTaO4以及二元氧化物Cr2O3， Nb2O5和Ta2O5的温度依赖热力学性质。计算得到的二元氧化物的热力学性质与实验数据进行了基准比对，除Nb2O5的负热膨胀（NTE）外，其精度较高，这是由于其多晶性的复杂性。将DFT预测的形成能与现有的SGTE物质数据库（SSUB5）相结合，发现CrNbO4和CrTaO4在1706 K和1926 K温度下是热力学稳定的，并分别分解为Cr2O3和Nb2O5或Ta2O5。对CrNbO4和CrTaO4的线性热膨胀系数的温度依赖性进行了预测，在500 K ~ 2000 K范围内，其平均值分别为6.0 × 10−6/K和5.04 × 10−6/K，与文献中的实验观测结果一致。结果表明，CrTaO4和CrNbO4的形成减少了铬的挥发，这对设计具有增强抗氧化性的增强型耐火高熵合金（RHEAs）至关重要。
{"title":"Temperature-dependent thermodynamic properties of CrNbO4 and CrTaO4 by first-principles calculations","authors":"Shuang Lin , Shun-Li Shang , Allison M. Beese , Zi-Kui Liu","doi":"10.1016/j.ijrmhm.2026.107728","DOIUrl":"10.1016/j.ijrmhm.2026.107728","url":null,"abstract":"<div><div>In the present work, the density functional theory (DFT) in the generalized-gradient approximation developed by Perdew, Burke, and Ernzerhof (PBE) + U method, i.e., PBE + U, was employed to predict temperature-dependent thermodynamic properties of the rutile-type oxides CrNbO<sub>4</sub> and CrTaO<sub>4</sub> as well as the binary oxides Cr<sub>2</sub>O<sub>3</sub>, Nb<sub>2</sub>O<sub>5</sub>, and Ta<sub>2</sub>O<sub>5</sub> via the quasiharmonic phonon approach (QHA). Calculated thermodynamic properties of the binary oxides were benchmarked with experimental data, showing high accuracy except for the negative thermal expansion (NTE) of Nb<sub>2</sub>O<sub>5</sub>, attributed to its polymorphic complexity. By combining the formation energy predicted by DFT with the existing SGTE Substances Database (SSUB5), the CrNbO<sub>4</sub> and CrTaO<sub>4</sub> are found to be thermodynamic stable up to 1706 K and 1926 K and decompose into Cr<sub>2</sub>O<sub>3</sub> and Nb<sub>2</sub>O<sub>5</sub> or Ta<sub>2</sub>O<sub>5</sub> at those temperatures, respectively. The temperature dependence of linear thermal expansion coefficients for CrNbO<sub>4</sub> and CrTaO<sub>4</sub> are predicted, and their mean values from 500 K to 2000 K are found to be 6.0 × 10<sup>−6</sup>/K and 5.04 × 10<sup>−6</sup>/K, respectively, in agreement with experimental observations in the literature. The gas-phase species and their vapor pressure are calculated, indicating that the formation of CrTaO<sub>4</sub> and CrNbO<sub>4</sub> reduces chromium volatilization, which is critically important to design enhanced refractory high entropy alloys (RHEAs) with enhanced oxidation resistance.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"138 ","pages":"Article 107728"},"PeriodicalIF":4.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146732","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 : 2026-08-01Epub Date: 2026-02-12DOI: 10.1016/j.jeurceramsoc.2026.118234
Jincheng Lin , Jiawei Bai , Sujun Liu , Lili Xing , Decai Ma , Xiujie He , Dongbai Sun , Tiesong Lin , Peng He , Weiqi Yang
The performance degradation caused by amorphization of crystals under irradiation is a critical challenge for glass-sealing joints applied in nuclear components. In this work, the behavior of phase separation of the Li2O-modified YAS glass was firstly used to join SiC ceramics. It’s found that the addition of Li2O promotes the separation of nanosized spherical quartz glass from the base glass above the softening temperature. Benefited from the “rigid-plastic” nanostructure, the glass with nanophase separation exhibit better indentation fracture toughness (1.1 MPa·m1/2) than the original glass (0.8 MPa·m1/2). The nanophase separation glass was successfully fabricated in the SiC brazing seam by pre-oxidizing proper thickness of SiO2 layer on SiC as well as applying a fast-cooling process, and the joint shear strength reached 129.8 ± 16.4 MPa, 44 % higher than the traditional joint with the same brazing glass. The possible toughing and formation mechanism of nanophase separation glass was discussed.
{"title":"Joining of SiC by Li2O-Y2O3-Al2O3-SiO2 glass with nanosized glassy phase separation","authors":"Jincheng Lin , Jiawei Bai , Sujun Liu , Lili Xing , Decai Ma , Xiujie He , Dongbai Sun , Tiesong Lin , Peng He , Weiqi Yang","doi":"10.1016/j.jeurceramsoc.2026.118234","DOIUrl":"10.1016/j.jeurceramsoc.2026.118234","url":null,"abstract":"<div><div>The performance degradation caused by amorphization of crystals under irradiation is a critical challenge for glass-sealing joints applied in nuclear components. In this work, the behavior of phase separation of the Li<sub>2</sub>O-modified YAS glass was firstly used to join SiC ceramics. It’s found that the addition of Li<sub>2</sub>O promotes the separation of nanosized spherical quartz glass from the base glass above the softening temperature. Benefited from the “rigid-plastic” nanostructure, the glass with nanophase separation exhibit better indentation fracture toughness (1.1 MPa·m<sup>1/2</sup>) than the original glass (0.8 MPa·m<sup>1/2</sup>). The nanophase separation glass was successfully fabricated in the SiC brazing seam by pre-oxidizing proper thickness of SiO<sub>2</sub> layer on SiC as well as applying a fast-cooling process, and the joint shear strength reached 129.8 ± 16.4 MPa, 44 % higher than the traditional joint with the same brazing glass. The possible toughing and formation mechanism of nanophase separation glass was discussed.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 9","pages":"Article 118234"},"PeriodicalIF":6.2,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191525","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 : 2026-08-01Epub Date: 2026-02-04DOI: 10.1016/j.jeurceramsoc.2026.118212
Xinyu Wang , Ruipeng Wang , Jianli Jiang , Haining Meng , Haigang Hou , Jian Yang , Guiwu Liu , Guanjun Qiao
PbTe-based thermoelectric materials are promising for mid-temperature waste heat recovery, yet n-type PbTe underperforms its p-type counterpart. Herein, high-performance n-type PbTe is achieved through I/Ge co-doping and in-situ composite engineering with Sb2Te3 prepared by melting combined spark plasma sintering. Sb2Te3 alloying introduce in-situ formed Sb/Sb2Te3 precipitates. Furthermore, iodine doping optimizes the carrier concentration to ∼3.4 × 1019 cm–3, boosting the room-temperature electrical conductivity to ∼1404 S cm−1 and yielding a high power factor of ∼17.4 μW cm−1 K−2 for the PbTe-Sb2Te3 sample. Meanwhile, lattice thermal conductivity is synergistically suppressed to ∼0.37 W m–1 K–1 at 673 K through Ge-induced point defects/off-center anharmonicity and Sb/Sb2Te3 precipitates. This synergistic strategy results in a peak ZT of ∼1.30 at 823 K and a high average ZT of ∼0.91 at 323–823 K. This work demonstrates that synergistic I/Ge co-doping and composite precipitation effectively enhance thermoelectric performance in n-type PbTe.
基于PbTe的热电材料有望用于中温废热回收，但n型PbTe的性能不如p型。本文通过I/Ge共掺杂和原位复合工程，以熔融组合火花等离子烧结法制备Sb2Te3，实现了高性能n型PbTe。Sb2Te3合金引入原位形成的Sb/Sb2Te3相。此外，碘掺杂将载流子浓度优化到~ 3.4 × 1019 cm - 3，将PbTe-Sb2Te3样品的室温电导率提高到~ 1404 S cm - 1，并产生了~ 17.4 μW cm - 1 K - 2的高功率因数。同时，通过锗诱导的点缺陷/偏心不谐性和Sb/Sb2Te3析出，晶格热导率协同抑制到~ 0.37 W m-1 K - 1（673 K）。这种协同策略导致在823 K处ZT峰值为~ 1.30，在323-823 K处ZT峰值为~ 0.91。本工作证明了协同I/Ge共掺杂和复合沉淀有效地提高了n型PbTe的热电性能。
{"title":"Synergistic enhancement of thermoelectric performance in n-type Sb2Te3 alloyed PbTe via I/Ge co-doping","authors":"Xinyu Wang , Ruipeng Wang , Jianli Jiang , Haining Meng , Haigang Hou , Jian Yang , Guiwu Liu , Guanjun Qiao","doi":"10.1016/j.jeurceramsoc.2026.118212","DOIUrl":"10.1016/j.jeurceramsoc.2026.118212","url":null,"abstract":"<div><div>PbTe-based thermoelectric materials are promising for mid-temperature waste heat recovery, yet n-type PbTe underperforms its p-type counterpart. Herein, high-performance n-type PbTe is achieved through I/Ge co-doping and in-situ composite engineering with Sb<sub>2</sub>Te<sub>3</sub> prepared by melting combined spark plasma sintering. Sb<sub>2</sub>Te<sub>3</sub> alloying introduce in-situ formed Sb/Sb<sub>2</sub>Te<sub>3</sub> precipitates. Furthermore, iodine doping optimizes the carrier concentration to ∼3.4 × 10<sup>19</sup> cm<sup>–3</sup>, boosting the room-temperature electrical conductivity to ∼1404 S cm<sup>−1</sup> and yielding a high power factor of ∼17.4 μW cm<sup>−1</sup> K<sup>−2</sup> for the PbTe-Sb<sub>2</sub>Te<sub>3</sub> sample. Meanwhile, lattice thermal conductivity is synergistically suppressed to ∼0.37 W m<sup>–1</sup> K<sup>–1</sup> at 673 K through Ge-induced point defects/off-center anharmonicity and Sb/Sb<sub>2</sub>Te<sub>3</sub> precipitates. This synergistic strategy results in a peak ZT of ∼1.30 at 823 K and a high average ZT of ∼0.91 at 323–823 K. This work demonstrates that synergistic I/Ge co-doping and composite precipitation effectively enhance thermoelectric performance in n-type PbTe.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 9","pages":"Article 118212"},"PeriodicalIF":6.2,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191688","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 : 2026-08-01Epub Date: 2026-02-03DOI: 10.1016/j.ijrmhm.2026.107717
Yu He , Xun Shen , Yifan Yan , Shuju Liang , Shuguang Cao , Jingyuan He , Jiangxia Liu , Chong Peng , Changjian Geng , Lingwei Kong , Kangkang Wen , Rui Li
Nanocrystalline (NC) tungsten (W) alloys with high thermal stability are needed for their use as plasma-facing materials in fusion reactors. In this work, the thermal stability of W alloys is optimized by yttrium (Y) doping, and the theoretical calculation and experimental verification are carried out. The link between the normalized grain boundary energy and the Y content (1–10 at.%) and the microstructural evolution were systematically investigated. Theoretical modeling showed an optimum Y doping range of 3–5 at.%, which thermodynamically stabilizes the nanostructure by lowering the grain boundary energy to below zero. WY alloys were synthesized experimentally by high-energy ball milling and high-pressure consolidation. W3Y and W5Y alloys showed excellent thermal stability, with sub-30 nm NC grain size after annealing at 1300 °C for 1 h, and W5Y alloy showed a Vickers hardness of 17.8 GPa, showing only 12.3% decrease compared to the as-sintered state. In contrast, the specific grain boundary energy was increased by excessive Y doping (e.g., 10 at.%), which reduced thermodynamic stability and made the material kinetically pinned by Y2O3 nanoparticles, which were found to be inadequate at higher temperatures. The results show that the synergistic effect of thermodynamic stabilization by Y segregation and kinetic stabilization by oxide pinning is responsible for the improved performance. This work offers a fundamental approach for the design of high-performance, nanoscale tungsten-based materials for extreme environments in fusion energy and other advanced nuclear systems.
{"title":"Enhancing the thermal stability of nanocrystalline tungsten alloys through optimized yttrium doping","authors":"Yu He , Xun Shen , Yifan Yan , Shuju Liang , Shuguang Cao , Jingyuan He , Jiangxia Liu , Chong Peng , Changjian Geng , Lingwei Kong , Kangkang Wen , Rui Li","doi":"10.1016/j.ijrmhm.2026.107717","DOIUrl":"10.1016/j.ijrmhm.2026.107717","url":null,"abstract":"<div><div>Nanocrystalline (NC) tungsten (W) alloys with high thermal stability are needed for their use as plasma-facing materials in fusion reactors. In this work, the thermal stability of W alloys is optimized by yttrium (Y) doping, and the theoretical calculation and experimental verification are carried out. The link between the normalized grain boundary energy and the Y content (1–10 at.%) and the microstructural evolution were systematically investigated. Theoretical modeling showed an optimum Y doping range of 3–5 at.%, which thermodynamically stabilizes the nanostructure by lowering the grain boundary energy to below zero. W<img>Y alloys were synthesized experimentally by high-energy ball milling and high-pressure consolidation. W<img>3Y and W<img>5Y alloys showed excellent thermal stability, with sub-30 nm NC grain size after annealing at 1300 °C for 1 h, and W<img>5Y alloy showed a Vickers hardness of 17.8 GPa, showing only 12.3% decrease compared to the as-sintered state. In contrast, the specific grain boundary energy was increased by excessive Y doping (e.g., 10 at.%), which reduced thermodynamic stability and made the material kinetically pinned by Y<sub>2</sub>O<sub>3</sub> nanoparticles, which were found to be inadequate at higher temperatures. The results show that the synergistic effect of thermodynamic stabilization by Y segregation and kinetic stabilization by oxide pinning is responsible for the improved performance. This work offers a fundamental approach for the design of high-performance, nanoscale tungsten-based materials for extreme environments in fusion energy and other advanced nuclear systems.</div></div>","PeriodicalId":14216,"journal":{"name":"International Journal of Refractory Metals & Hard Materials","volume":"138 ","pages":"Article 107717"},"PeriodicalIF":4.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146110059","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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