工业原料制备高强韧非晶钢的成分调控、相变及变形机制研究

非晶钢具有超高强度，但加载时表现为室温脆性和应变软化，且目前报道的增韧方法效果有限，严重制约了其作为高性能结构材料的应用。本课题选择价格低廉、同时具有形状记忆效应和非晶形成能力的Fe-Mn-Si合金体系，通过成分优化使非晶基体上原位析出单一γ奥氏体相，在应力诱导下产生γ→ε马氏体相变对非晶基体增强增韧，且这种新型室温无磁非晶复合结构钢的屈强比低、屈服强度可控；在此基础上探索由工业原料在低真空度下制备合金，通过添加混合稀土元素对亲氧除杂的协同作用，进一步优化组织并降低成本。本课题将分析成分调控对残余奥氏体相稳定性和合金非晶形成能力的影响，揭示层错机制对马氏体相转变过程的作用规律，研究非晶基体剪切带的间歇性运动行为和分形特征，并由承载时的加工硬化行为分析不同变形阶段起主导作用的强韧化机理，揭示TRIP效应对非晶基体的韧塑化机制，为发展新型的高性能非晶钢提供新的思路和理论参考。

Amorphous steels exhibit ultra high strength but room-temperature brittleness and strain-softening behavior as loading. The reported toughening methods had very limited results, and restricted the application of amorphous steels as high-performance structural material. This project designs to study the cheap Fe-Mn-Si alloy system with shape memory effect and glass forming ability. And the amorphous matrix can be strengthened and toughened by deformation induced γ→ε martensitic transformation, which is transformed from the in-situ formed single supercooled austenitic phase during solidification by optimizing composition. This new type of room-temperature non-magnetic amorphous matrix composites structural steel exhibits controllable yield strength and low yield ratio. Besides, this project designs to prepare the amorphous steels from industrial raw materials at low vacuum. And the synergistic effect of the mixed rare earth elements addtion on oxygen and impurity removal will be studied, to further optimize the microstructure and reduce the costs. This project will study the effects of component control on the stability of residual austenite and the glass forming ability of the composites. And the interaction rules of stacking fault mechanism on the process of martensite transformation will be revealed. The intermittent motion behavior and fractal characteristics of the shear bands of amorphous matrix will be described. Moreover, the work-hardening behavior as loading will be analized to study the dominant strengthening and toughening mechanism at different deformation stage. Thus, the toughing mechanism of TRIP effect on the amorphous matrix will be elucidated. This project will provide new ideas and theoretical reference for the development of new high performance structural amorphous steel.