Atomic-scale insights into CMAS-induced grain boundary embrittlement in thermal barrier ceramics

IF 5.8 2区材料科学 Q1 MATERIALS SCIENCE, CERAMICS

Journal of The European Ceramic Society Pub Date : 2025-04-21 DOI:10.1016/j.jeurceramsoc.2025.117472

Yang Liu, Craig J. Williams, Ping Xiao, Ying Chen

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Abstract

We report a study on grain boundary (GB) embrittlement in yttria stabilised zirconia (YSZ) ceramics induced by calcia-magnesia-alumino-silicate (CMAS). Model ceramics composed of tetragonal YSZ grains and intergranular CMAS were fabricated through sintering of YSZ-CMAS powder mixtures with incremental CMAS additions up to 1 wt%. Microstructural characterisations reveal that, although glassy CMAS films are present at triple junctions and between YSZ grains, most GBs are free of glassy films but enriched with CMAS-derived impurities. As the CMAS content increases the fracture toughness drops significantly, and the fracture mode shifts increasingly towards intergranular. Fractographic analysis at the atomic scale shows that fractures occur within the cores of glass-free GBs, whereas in GBs containing glassy CMAS films, fractures occur at the CMAS/YSZ interface, where a 2 nm layer of monoclinic YSZ is present. The CMAS-induced grain boundary embrittlement is explained from the perspective of fracture energy, with contributions from GB energy, ionic bonding, oxygen vacancies and ionic size mismatch taken into consideration.

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cmas诱导的热障陶瓷晶界脆化的原子尺度研究

本文报道了由钙镁铝硅酸盐（CMAS）诱导的钇稳定氧化锆（YSZ）陶瓷的晶界脆化（GB）。通过YSZ-CMAS粉末混合物烧结制备了由四边形YSZ颗粒和晶间CMAS组成的模型陶瓷，CMAS添加量为1 wt%。微观结构表征表明，尽管玻璃状的CMAS膜存在于三结处和YSZ晶粒之间，但大多数GBs没有玻璃膜，但富含CMAS衍生的杂质。随着CMAS含量的增加，断裂韧性显著下降，断裂模式逐渐向晶间转变。在原子尺度上的断口分析表明，裂缝发生在不含玻璃的gb / s岩心内，而在含有玻璃状CMAS薄膜的gb / s岩心中，裂缝发生在CMAS/YSZ界面上，在那里存在一个2 nm的单斜YSZ层。从断裂能的角度解释cmas引起的晶界脆化，考虑了GB能、离子键、氧空位和离子尺寸失配的贡献。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of The European Ceramic Society 工程技术-材料科学：硅酸盐

CiteScore

10.70

自引率

12.30%

发文量

863

审稿时长

35 days

期刊介绍： The Journal of the European Ceramic Society publishes the results of original research and reviews relating to ceramic materials. Papers of either an experimental or theoretical character will be welcomed on a fully international basis. The emphasis is on novel generic science concerning the relationships between processing, microstructure and properties of polycrystalline ceramics consolidated at high temperature. Papers may relate to any of the conventional categories of ceramic: structural, functional, traditional or composite. The central objective is to sustain a high standard of research quality by means of appropriate reviewing procedures.