优异的高温抗氧化性能是高熵二硼化物（HEBs）作为热结构材料使用的重要前提。
近日，华南理工大学褚衍辉教授和庄磊副教授等人在Science China Materials发表研究论文，通过对(Zr, Ta, Cr, W)B2体系进行组分筛选，成功开发了具有优异抗氧化性能的HEBs材料。
本文要点
1) 首先通过超快超高温烧结技术制备了21种HEBs-xTM（x = 0–25 mol%, TM = Zr、Ta、Cr和W）试样，随后对所制备HEBs试样的抗氧化性能进行了测试表征。2) 相比于其他试样，HEB-5Cr样品在1673 K温度下表现出最佳的抗氧化性能；在随后的1473–1773 K等温氧化过程中，其氧化行为被证实遵循抛物线规律，说明其具有优异的抗氧化性能。3) 优异的性能主要归因于多组元协同效应，即高离子场强的Ta5+和W4+可以通过平衡电荷促进[BO4]四面体之间4B–O–4B键的形成，稳定B2O3玻璃的三维骨架结构，提高B2O3玻璃层的粘度；而高熔点的ZrO2和Cr2O3复杂氧化物则可以溶解到B2O3玻璃中，增加其玻璃态转变温度，也可以提高B2O3玻璃层的粘度。Figure 1. Microstructures and elemental distributions of the as-fabricated HEB-15Zr and HEB-5Cr samples. (a) BSE image of the HEB-15Zr sample. (b) Corresponding EDS mappings of (a). (c) BSE image of the HEB-5Cr sample. (d) Corresponding EDS mappings of (c).Figure 2. Oxidation testing results of the as-fabricated HEB samples. (a) Oxidation depths of all the HEB samples after isothermal oxidation at 1673 K for 30 min. (b) Oxidation weight changes of the HEB-5Cr samples at 1473–1773 K. (c) The plots of (ΔW/A)2 vs. oxidation time of the HEB-5Cr samples at 1473–1773 K. (d) The Arrhenius plot of the parabolic rate constants of the HEB-5Cr samples.Figure 3. SEM-EDS analyses of the oxidation surfaces and cross-sections of the as-fabricated HEB-0Ta, HEB-5Cr, and HEB-10Cr samples after oxidation at 1673 K for 30 min. Oxidation surfaces of the (a) HEB-0Ta, (b) HEB-5Cr, and (c) HEB-10Cr samples. Oxidation cross-sections of the (d) HEB-0Ta, (e) HEB-5Cr, and (f) HEB-10Cr samples. (g) Corresponding EDS compositional mappings of (e). (h) BSE image of the enlarged area of (e) and corresponding EDS mappings.Figure 4. Schematic of potential oxidation resistance mechanism of HEB-5Cr samples. (a)Initial stage. (b) Middle stage. (c) Structural enlargement of the formed B2O3 in (b). (d) Late stage. (e) Structural enlargement of the formed TMOs-B2O3 in (d). (f) Last stage.Zhongyu Tang, Zihao Wen, Lei Zhuang, Hulei Yu, Yanhui Chu. Enhanced oxidation resistance of high-entropy diborides by multi-component synergistic effects. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-3045-4
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