大块非晶形成体系的深过冷行为及原子短程序结构研究

Due to their excellent physical, chemical and mechanical properties, bulk Metallic glasses (BMGs) have attracted much attention in the past decade. However, the formation mechanism of BMGs has not been fully understood so far. In this project, under the financial support of NSFC, we hope to make a tiny contribution to this aspect through systematical study of the formation and atomic short-range structure of various bulk metallic glasses.In this project, we have systematically studied the formation, atomic short-range structure, thermal stability and rheology of different BMGs, such as Zr-based, Pd-based and Fe-based bulk metallic glasses. Thermal analyzer (DSC/DTA) was used to investigate the isothermal and isochroous kinetics of crystallization and quasicrystallization. Synchro-radiation small angle x-ray scattering was employed to study the changes of short-range structure of Zr-based BMG during structural relaxation and glass transition. To develop novel bulk metallic glasses, through multi-metalloids addition, we have successfully prepared Fe-based bulk metallic glasses with low purity of materials. The soft-magnetic properties of the Fe-based bulk metallic glass can be considerably enhanced via addition of a trace amount of Ni and proper heat treatments. Additionally, the rheology of Zr-base and Pd-based BMGs was analyzed by static extension measurements, and relationship between atomic diffusion coefficient and viscosity has been established in terms of Stoke-Einstein formulae. Apart from the experimental and theoretical studies on BMGs, we have set up a new equipment for preparation of BMGs, which combines suck casting and press-casting. Based on the researches for the project, we have published 8 papers (several others are under-preparation), and tutored 3 master students and 1 Ph.D student. In addition, we have established good cooperation with The Hong Kong Polytechnic University and The National University of Singapore.

本项目采用实验测试和理论计算相结合的方法深入研究大块非晶形成体系的深过冷行为和非晶形成机制。在实验上借助多种测试手段研究合金的非晶态及过冷液态的原子结构，原位探测合金熔体的过冷度并研究对其的影响因素。在理论上通过热力学函数的计算和分子动力学模拟揭示大块非晶形成体系具有强非晶形成能力的物理本质。