具有优异高温强度和抗氧化性能的钼硅硼合金是下一代高温合金的最佳候选材料之一，但其低的室温断裂韧性导致的可加工性能差严重制约了实际应用推广。本申请拟在双尺度分布氧化镧掺杂钼硅硼合金材料体系基础上，设计和制备具有“粗晶/细晶双尺度连续分布的钼基体上均匀分布有细晶金属间化合物，且占绝大多数的纳米氧化镧颗粒在晶内均匀分布，少量的亚微米氧化镧颗粒分布在晶界或相界上”微观组织特征的钼硅硼合金，通过对微观组织的定量表征，以及室温/高温力学性能与抗氧化性能的测试，系统研究不同温度下合金微观组织变化对合金变形行为与抗氧化性能的影响规律，建立微观组织与性能之间的联系，揭示合金中双尺度钼晶粒与双尺度氧化镧颗粒的单独和耦合强韧化机制，阐明微观结构参数及其耦合作用所影响的强韧化微观机理。研究结果将确定钼硅硼合金强韧化的最佳微观组织特征参数，并为通过微观组织的优化设计以改善钼硅硼合金的综合性能提供实验数据和理论基础。

The Mo-Si-B alloy, having excellent high temperature strength and oxidation resistance property, is most potential candidate for the next generation of high-temperature alloy materials. However, the low fracture toughness and concomitantly insufficient workability at room temperature seriously restrict the practical applications of the alloy. This project is focused on the design and preparation of a new Mo-Si-B alloy with bimodal grains (coarse and fine grains) and dual lanthanum oxide particle distribution. The microstructure characteristic of the alloy is fine-grained intermetallic distributed on coarse/fine-grained molybdenum substrate, meanwhile a great number of nano-sized lanthanum oxide particles are homogeneously distributed in the grain interior, while a small amount of submicron lanthanum oxide particles locate at the grain boundaries or phase boundaries. The microstructures will be comprehensively and quantitatively characterized, and the mechanical properties at room temperature and high temperatures as well as the oxidation resistance property of the alloy will be measured. Relationships between the microstructure and mechanical properties will be developed and strengthening/toughening model will be proposed to reveal the individual and coupled strengthening and toughening mechanism of the multiple microstructures. Optimization of the microstructure will be achieved in this project to reach the best strength/toughness combination in the Mo-Si-B alloy, which will be helpful for the alloy design and microstructural tailoring to improve the properties of the advanced Mo-Si-B alloys.