高速钢中W-Mo-Cr-V-Ti等合金元素形成硬质相的微观机制及性能调控

Iron and steel industry were developed quickly in last the century, which is a symbol for the modern industry. The super steel plan or new iron materials are coming to front. However, the fundamental properties like physical, chemistry, mechanical, thermodynamics, etc. of reinforcement are lacked in traditional research. In addition, the mechanisms of the effects and properties of steel by reinforcement are unknown in the current world. Owing to these reasons, the progress of iron and steel is similar to stop in discovery new materials. In this research, the common alloying elements included W, Mo, Cr, V and Ti, etc. in high-speed steel will be studied as an example. The mechanism of alloying would be explored by experiments and calculations. We will apply the XRD, SEM, TEM and simulation to characterize the structures and properties of reinforcements. The stability, thermodynamics, mechanical and thermal properties of carbides will be discussed deeply in our research. Then, the new rules among these properties with the compounds are going to be discovered by first principles. Hence, we would know the reasons which affect the properties in electron-atom level. Moreover, we could design the new iron and steel by the theory in this research.

新型钢铁材料工业在20世纪高速发展，成为各国工业化的重要标志，超级钢研究计划或新一代钢铁材料研究备受关注，然而多元硬质相的基本物理化学力学性质难以获得，导致在整个世界范围内对钢铁中第二相形成的机理和性质缺乏全面深入的了解，从基础研究方面限制了新型钢铁材料的开发与研究。本项目以高强高韧高速钢中常见添加合金元素为例，深入探讨W-Mo-Cr-V-Ti等合金元素形成硬质相的机制，结合计算模拟及微结构表征技术，对其中硬质相的性质进行研究，包括稳定性、热力学、力学及物理化学性质等，结合第一原理计算从电子-原子层次上探索各类硬质相的形成机制、结构及力学性质规律，总结其电子结构和化学键合对力学行为影响的科学本质，通过深入了解硬质相的性质来调控硬质相的选择、工艺等，从而为新一代高速钢的设计和研究提供理论基础与支撑，具有重要的理论意义和工程应用价值。

高速钢中的硬质相对钢铁材料的整体性能起到重要影响。然而由于硬质相尺寸小、化学组成复杂，导致多元硬质相的基本物理化学力学性质难以获得。基础数据的缺失限制了新型高速钢材料的开发与研究。本项目以常用的高速钢为例，采用电子探针微区分析仪和纳米压痕技术表征了硬质相的化学组成和力学性质，结合第一性原理计算从电子-原子层次上计算获得各类硬质相的形成机制、结构、化学键特征及力学性质，总结W-Mo-Cr-V-Ti 等合金元素形成硬质相的电子结构和化学键合对力学性质的影响规律。克服了钢铁中硬质相尺寸小、化学组成复杂从而难以测试其组成和性质的难题。其中部分多元合金化硬质相的力学、热学性质在国际上为首次得到。结果表明，通过纳米压痕测试获得M6C的杨氏模量为300 GPa，硬度为20 GPa，M2C相中h-W2C脆性相对较大，Mo或W的掺杂能改善M7C3型硬质相的韧性，MC型硬质相的硬度高于M2C和M23C6型，其中h-WC和V8C7的硬度值最大。通过对钢铁中硬质相形成机理和性质的全面深入了解，为硬质相的选择提供思路，为目前高速钢的性能提升、新型高速钢的设计提供理论基础与支撑，具有重要的理论意义和工程应用价值。