Microstructure, room-temperature mechanical properties, and oxidation resistance of Mo-12Si-8B-xTi (x = 10, 20, 30, 40, at.%) alloys fabricated via hot pressing sintering are investigated. 10Ti and 20Ti alloys comprise α-Mo + Mo₃Si + Mo₅SiB₂, whereas 30Ti and 40Ti alloys comprise α-Mo + Mo₅SiB₂ + Ti₅Si₃. CALPHAD thermodynamic modeling and EDS indicate a significant increase in Ti solubility in α-Mo and Mo₅SiB₂ phases with higher Ti content, reaching levels of 30–50%. EBSD analysis reveals evident grain coarsening, the average grain size improves from 1.43 to 2.97 μm. HRTEM characterization demonstrates α-Mo/Mo₅SiB₂ and α-Mo/Ti₅Si₃ interfaces are both incoherent. 10Ti alloy exhibits the highest flexural strength of 454 MPa and fracture toughness of 9.9 MPa‧m^1/2, while minor differences in fracture toughness are observed among 20–40Ti alloys. The combination of adequate α-Mo matrix, appropriate grain size, and brittle intermetallic phases collectively contribute to determining the strength and toughness. Simultaneous thermal analysis and cyclic oxidation show 40Ti alloy offers the best oxidation resistance at 800–1200 °C, because of the protective TiO₂‧SiO₂ layer generated through selective oxidation of Ti₅Si₃ and Ti/Si. Using Pilling-Bedworth ratio as the sole criterion to assess the oxidation resistance is inadequate, as temperature and phase constitution must be considered.

中文翻译：

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通过热压烧结制备的添加 Ti 的 Mo-Si-B 合金的微观结构、室温机械性能和抗氧化性


研究了通过热压烧结制备的 Mo-12Si-8B-x Ti （x = 10， 20， 30， 40， at.%） 合金的微观组织、室温机械性能和抗氧化性。10Ti 和 20Ti 合金包括 α-Mo_{+ Mo 3}Si + Mo₅SiB₂，而 30Ti 和 40Ti 合金包括 α-Mo_{+ Mo 5}SiB₂ + Ti₅Si₃。CALPHAD 热力学建模和 EDS 表明，Ti 在 Ti 含量较高的 α-Mo 和 Mo₅SiB₂ 相中溶解度显著增加，达到 30-50% 的水平。EBSD 分析显示明显的晶粒粗化，平均晶粒尺寸从 1.43 μm 提高到 2.97 μm。HRTEM 表征表明 α-Mo/Mo₅SiB₂ 和 α-Mo/Ti₅Si₃ 界面都是不相干的。10Ti 合金表现出最高的弯曲强度 454MPa 和 9.9MPa‧m^1/2，而 20-40Ti 合金之间的断裂韧性差异很小。足够的 α-Mo 基体、适当的晶粒尺寸和脆性金属间化合物相的组合共同有助于确定强度和韧性。同时进行热分析和循环氧化表明，40Ti 合金在 800-1200 °C 时具有最佳的抗氧化性，因为 Ti₅Si₃ 和 Ti/Si 选择性氧化会产生保护性 TiO₂‧SiO₂ 层。使用 Pilling-Bedworth 比作为评估抗氧化性的唯一标准是不够的，因为必须考虑温度和相组成。