纳米La2O3掺杂及强场诱导Mo2NiB2金属陶瓷的组织演变和多尺度作用机理研究

Mo2NiB2金属陶瓷具有良好的室温加工性能和优异的高温综合力学性能，有望开辟高温结构材料的应用新前景，但其高温烧结过程易导致晶粒长大，从而降低材料室温断裂韧性与高温强度。基于纳米La2O3的细晶韧化、颗粒的裂纹桥接与偏转可提高金属陶瓷的室温断裂韧性，其颗粒钉扎作用和提高再结晶温度效果可提高材料的高温强度，以及强磁场诱导Mo2NiB2金属陶瓷细化晶粒的设想，研究纳米La2O3掺杂Mo2NiB2金属陶瓷及强磁场诱导组织演变、细化晶粒技术，通过对纳米La2O3掺杂Mo2NiB2金属陶瓷的力学性能测试及各相的尺度和体积分数等微观组织变化的表征，研究纳米La2O3掺杂与强磁场诱导所引起的微观组织演变、晶粒多尺度分布及其对性能的影响规律，阐明Mo2NiB2金属陶瓷中微观组织演变、颗粒/晶粒多尺度分布所影响的强韧化和抗氧化效果的微观机理，为发展细晶高强韧Mo2NiB2金属陶瓷提供新的思路和理论基础。

Mo2NiB2 metal ceramic has attracted great attention due to its processing properties at room temperature and high temperature mechanical properties. However, the bottleneck problem of grain growth caused during the high temperature sintering process can reduce the fracture toughness and high temperature strength of the material. Based on some assumptions that, fine grain toughening, crack bridging and deflection of nano La2O3 particles can improve the fracture toughness, particle pinning and elevated recrystallization temperature can heighten the high temperature strength, and Mo2NiB2 metal ceramic grains can be refined with strong magnetic field oscillating. The preparation technology of Mo2NiB2 metal ceramics doped with nano La2O3 particles, and the microstructure evolution, grain refinement technique by high magnetic field oscillation are revealed. Furthermore, the characterization of microstructure such as the size and volume fraction of each phase in Mo2NiB2 metal ceramics are investigated, so as to realize the microstructure evolution, grain multi-scale distribution and the influencing rule on the properties of the cermet with nano La2O3 doping and assisted grain refinement technique by strong magnetic field. This research will study the micromechanism of toughening and antioxidation caused by microstructure evolution and multiscale distribution of particles or grains, which can provide a new idea and theoretical basis for the development of fine grain, high strength and toughness of Mo2NiB2 cermet.