大块金属玻璃微观结构演变的原位同步辐射研究

For the deformation behavior of bulk metallic glass (BMG), more attention has been paid to the plastic flow behavior after yielding, the establishment of the yield criterion and the fracture process. The elastic stage of structural changes, however, directly affects the elastic energy, yield strength and plastic strain of BMGs. Therefore, it is an urgent scientific issues to understand the structural changes of amorphous phase with the evolution of the elastic strain, as well as the origin of plasticity and strength of BMGs. In this project, different elastic modulus and fracture toughness such as Zr-based, Mg-based and NiNb metallic glasses have been selected in this investigations. The high energy X-ray synchrotron radiation has been chosen to observe the in-situ evolution of the atomic structure from elastic deformation until fracture. The association among the internal states of the material, the structure and mechanical properties of BMGs will be discussed. Furthermore, the key factors which affect the mechanical properties of BMGs would be summarized. Our study might be helpful to understand the whole evolution process from elastic deformation until the final fracture.

对于大块金属玻璃（BMG）变形行为的研究，人们往往更关注于屈服后的塑性流变行为、屈服准则的建立和断裂过程。然而弹性阶段的结构变化直接影响着大块金属玻璃的弹性能、屈服强度和塑性应变能力。因此，了解非晶相结构随弹性应变的演化规律，是理解大块金属玻璃塑性和强度起源所急需解决的科学问题。本项目选取不同弹性模量和断裂韧性的Zr基、Mg基和NiNb大块金属玻璃等作为研究对象，通过高能同步辐射X射线原位（in-situ）观察大块金属玻璃弹性变形直至断裂过程中的原子结构的演化，深入分析材料的内部状态与材料结构和力学性能的关联。分析提出影响大块金属玻璃力学性能的主要因素。相关研究对于深入理解大块金属玻璃从弹性变形直至断裂整个演变过程可能起到很重要的作用。

对于大块金属玻璃（BMG）变形行为的研究，人们往往更关注于屈服后的塑性流变行为、屈服准则的建立和断裂过程。然而弹性阶段的结构变化直接影响着大块金属玻璃的弹性能、屈服强度和塑性应变能力。因此，了解非晶相结构随弹性应变的演化规律，是理解大块金属玻璃塑性和强度起源所急需解决的科学问题。本项目主要以Zr41.25Ti13.75Ni10Cu12.5Be22.5为模型材料，利用高能X射线同步辐射研究了当温度降低到低温时大块金属玻璃（BMG）原子级别结构的演变。发现BMG的强度和原子结构演变密切相关，在较低温度下，协同移动区内的原子激活能是影响屈服强度的主要因素。在此基础上，探索了多孔非晶合金及功能-结构一体化复合材料的制备及性能表征。研究结果可能会提供BMG在原子尺度结构演变的基础理解，还可能成为BMG原子结构的变化与宏观断裂强度之间的桥梁。