In this study, the multi-shell structured Mo-Si-B powder with LaO particles (MSB + L powder) was designed to obtain the ideal microstructure of sintered body, and the effects of the LaO addition on the microstructural and mechanical characteristics were investigated. Mo-Si-B powder (MSB powder) was prepared via mechano-chemical powder metallurgy methods, and MSB + L multi-shell powder was fabricated via chemical methods such as mixing and calcination processes. Using this powder, MSB + L alloys were prepared under cold isostatic pressing followed by pressureless sintering. Our unique powder's architecture allows us to fabricate the ideal microstructure of MSB + L alloys which consist of isolated intermetallic compound phases and uniformly dispersed LaO particles in continuous α-Mo matrix. This ideal microstructure contributes to the enhancement of fracture toughness of MSB + L alloys by changing fracture behavior, compared to MSB alloys without LaO particles. For example, intergranular fracture mode in MSB alloys changed to intragranular fracture mode in MSB + L alloys. In addition, the fracture toughness was enhanced around 26% in MSB with 0.3 wt% LaO particle at room temperature (17.0 MPa·m) while MSB alloys have around 13.50 MPa·m. The addition of LaO particles in MSB alloys highly affect the fracture behavior at room temperature through the grain refinement and oxide particle strengthening.

中文翻译：

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Mo-Si-B + La2O3 粉末的新颖设计，具有多壳结构，可实现理想的微观结构并增强机械性能

本研究设计了含有La2O颗粒的多壳结构Mo-Si-B粉末（MSB+L粉末）以获得理想的烧结体微观结构，并研究了La2O的添加对其微观结构和力学特性的影响。采用机械力化学粉末冶金方法制备Mo-Si-B粉末（MSB粉末），通过混合、煅烧等化学方法制备MSB+L多壳粉末。使用这种粉末，通过冷等静压和无压烧结制备了 MSB + L 合金。我们独特的粉末结构使我们能够制造出 MSB + L 合金的理想微观结构，该合金由孤立的金属间化合物相和连续 α-Mo 基体中均匀分散的 La2O 颗粒组成。与不含 La2O 颗粒的 MSB 合金相比，这种理想的微观结构有助于通过改变断裂行为来提高 MSB + L 合金的断裂韧性。例如，MSB合金中的晶间断裂模式变为MSB+L合金中的晶内断裂模式。此外，添加0.3 wt% La2O颗粒的MSB在室温下的断裂韧性提高了约26%（17.0 MPa·m），而MSB合金的断裂韧性约为13.50 MPa·m。MSB合金中添加的La2O颗粒通过晶粒细化和氧化物颗粒强化，极大地影响了室温下的断裂行为。