Investigating scandium-alloyed NbSi systems: Microstructure, oxidation behavior, and fracture toughness

IF 4.8 2区材料科学 Q1 MATERIALS SCIENCE, CHARACTERIZATION & TESTING Materials Characterization Pub Date : 2024-09-23 DOI:10.1016/j.matchar.2024.114409

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Abstract

In order to synchronize the oxidation resistance and room temperature fracture toughness of NbSi based alloys to meet the development needs, the effects of Sc addition on microstructure evolution, oxidation resistance and mechanical performance of Nb-16Si-20Ti-1.5Zr-1C-1B-xSc (x = 0, 0.1, 0.3, 0.5, 0.8) alloys are studied systematically. All compositions of the alloys are composed of two phases, Nbss and γ-(Nb,X)₅Si₃, X-ray diffraction and electron microscopy reveal that Sc addition refines γ-(Nb,X)₅Si₃ phases and promotes a transition from primary to lamellar eutectic structures, enhancing oxidation resistance. Sc₂O₃ formation at phase boundaries impedes oxygen diffusion, forming continuous oxide barriers (TiO₂ and SiO₂), thereby improving oxidation resistance. Mechanical testing shows an increase in fracture toughness with Sc doping, attributed to enhanced crack deflection and energy absorption within the Nbss phase. These results are important for the simultaneous improvement of room-temperature fracture toughness and high-temperature oxidation resistance as well as the mechanism of action of the rare earth element Sc, and for the further development of NbSi based superalloys to meet practical needs.

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研究钪合金化铌硅体系：微观结构、氧化行为和断裂韧性

为了使 NbSi 基合金的抗氧化性和室温断裂韧性同步发展，系统研究了添加 Sc 对 Nb-16Si-20Ti-1.5Zr-1C-1B-xSc (x = 0, 0.1, 0.3, 0.5, 0.8) 合金的微观结构演变、抗氧化性和力学性能的影响。X 射线衍射和电子显微镜显示，Sc 的加入细化了 γ-(Nb,X)5Si3 相，并促进了从原生结构到片状共晶结构的转变，从而增强了抗氧化性。在相界形成的 Sc2O3 会阻碍氧气扩散，形成连续的氧化物屏障（TiO2 和 SiO2），从而提高抗氧化性。机械测试表明，掺杂 Sc 后断裂韧性增加，这归因于 Nbss 相内裂纹偏转和能量吸收的增强。这些结果对于同时提高室温断裂韧性和高温抗氧化性以及稀土元素 Sc 的作用机理，以及进一步开发 NbSi 基超耐热合金以满足实际需求具有重要意义。

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来源期刊

Materials Characterization 工程技术-材料科学：表征与测试

CiteScore

7.60

自引率

8.50%

发文量

746

审稿时长

36 days

期刊介绍： Materials Characterization features original articles and state-of-the-art reviews on theoretical and practical aspects of the structure and behaviour of materials. The Journal focuses on all characterization techniques, including all forms of microscopy (light, electron, acoustic, etc.,) and analysis (especially microanalysis and surface analytical techniques). Developments in both this wide range of techniques and their application to the quantification of the microstructure of materials are essential facets of the Journal. The Journal provides the Materials Scientist/Engineer with up-to-date information on many types of materials with an underlying theme of explaining the behavior of materials using novel approaches. Materials covered by the journal include: Metals & Alloys Ceramics Nanomaterials Biomedical materials Optical materials Composites Natural Materials.