为了研究三元碳化物固溶体材料的低温氧化行为,利用等温暴露氧化实验方法研究了(Zr _(1/3) Nb _(1/3) Ti _(1/3))C固溶体陶瓷在不同低温空气中的氧化行为。研究结果表明,在1073~1473 K温度范围内,(Zr _(1/3) Nb _(1/3) Ti _(1/3))C固溶...为了研究三元碳化物固溶体材料的低温氧化行为,利用等温暴露氧化实验方法研究了(Zr _(1/3) Nb _(1/3) Ti _(1/3))C固溶体陶瓷在不同低温空气中的氧化行为。研究结果表明,在1073~1473 K温度范围内,(Zr _(1/3) Nb _(1/3) Ti _(1/3))C固溶体陶瓷具有优良的低温抗氧化性能,其氧化动力学符合抛物线规律,氧化过程受氧气在氧化层中的扩散速率控制;随着氧化温度升高,该材料的氧化速率常数表现出先缓慢降低、再迅速增加、最后逐渐降低的趋势。上述结果可主要归因于该陶瓷在不同温度下形成的氧化层的物相组成及微观结构的演变,即该材料在1073~1173 K温度下的氧化产物主要是由简单的ZrO_(2)、Nb_(2) O_(5)和TiO_(2)相组成,而在1273~1473 K温度下的氧化产物主要是由复杂的ZrTiO_(4)、TiNb_(2) O 7和Nb_(2) Zr_(6) O_(17)相组成,且随着氧化温度的升高,氧化产物的表面微观结构经历了致密-多孔-致密的演变过程,截面微观结构经历了致密-分层-致密的演变过程。展开更多
High-entropy ceramics(HECs) are gaining significant interest due to their huge composition space, unique microstructure, and adjustable properties. Previously reported studies focus mainly on HECs with the multi-catio...High-entropy ceramics(HECs) are gaining significant interest due to their huge composition space, unique microstructure, and adjustable properties. Previously reported studies focus mainly on HECs with the multi-cationic structure, while HECs with more than one anion are rarely studied. Herein we reported a new class of HECs, namely highentropy alumino-silicides(Mo0.25Nb0.25Ta0.25V0.25)(Al0.5Si0.5)2(HEAS-1) with multi-cationic and-anionic structure. The formation possibility of HEAS-1 was first theoretically analyzed from the aspects of thermodynamics and lattice size difference based on the first-principles calculations and then the HEAS-1 were successfully synthesized by the solid-state reaction at 1573K. The as-synthesized HEAS-1 exhibited good single-crystal hexagonal structure of metal alumino-silicides and simultaneously possessed high compositional uniformity.This study not only enriches the categories of HECs but also will open up a new research field on HECs with multi-cationic and-anionic structure.展开更多
基金National Natural Science Foundation of China(51802100,51972116)。
文摘为了研究三元碳化物固溶体材料的低温氧化行为,利用等温暴露氧化实验方法研究了(Zr _(1/3) Nb _(1/3) Ti _(1/3))C固溶体陶瓷在不同低温空气中的氧化行为。研究结果表明,在1073~1473 K温度范围内,(Zr _(1/3) Nb _(1/3) Ti _(1/3))C固溶体陶瓷具有优良的低温抗氧化性能,其氧化动力学符合抛物线规律,氧化过程受氧气在氧化层中的扩散速率控制;随着氧化温度升高,该材料的氧化速率常数表现出先缓慢降低、再迅速增加、最后逐渐降低的趋势。上述结果可主要归因于该陶瓷在不同温度下形成的氧化层的物相组成及微观结构的演变,即该材料在1073~1173 K温度下的氧化产物主要是由简单的ZrO_(2)、Nb_(2) O_(5)和TiO_(2)相组成,而在1273~1473 K温度下的氧化产物主要是由复杂的ZrTiO_(4)、TiNb_(2) O 7和Nb_(2) Zr_(6) O_(17)相组成,且随着氧化温度的升高,氧化产物的表面微观结构经历了致密-多孔-致密的演变过程,截面微观结构经历了致密-分层-致密的演变过程。
基金supported by the National Key Research and Development Program of China (2017YFB0703200)Young Elite Scientists Sponsorship Program by China Association for Science and Technology (2017QNRC001)the National Natural Science Foundation of China (51802100 and 51972116)
文摘High-entropy ceramics(HECs) are gaining significant interest due to their huge composition space, unique microstructure, and adjustable properties. Previously reported studies focus mainly on HECs with the multi-cationic structure, while HECs with more than one anion are rarely studied. Herein we reported a new class of HECs, namely highentropy alumino-silicides(Mo0.25Nb0.25Ta0.25V0.25)(Al0.5Si0.5)2(HEAS-1) with multi-cationic and-anionic structure. The formation possibility of HEAS-1 was first theoretically analyzed from the aspects of thermodynamics and lattice size difference based on the first-principles calculations and then the HEAS-1 were successfully synthesized by the solid-state reaction at 1573K. The as-synthesized HEAS-1 exhibited good single-crystal hexagonal structure of metal alumino-silicides and simultaneously possessed high compositional uniformity.This study not only enriches the categories of HECs but also will open up a new research field on HECs with multi-cationic and-anionic structure.
