探索非晶态合金塑性流动的结构起源

Amorphous allows, as advanced structural materials, show widely potential applications in the fields of defense and aerospace projects. Amorphous alloys possess long-range disordered atomic structures, without traditional crystalline defects such as dislocations and grain boundaries. Thus, the classical plasticity theory based on dislocation and twinning poses a big challenge to describe the plastic behavior of these materials.Up to now,however, little is known on the structural origin and physical mechanism for plastic flow of amorphous alloys.Therefore,the purpose of this research is to (1) characterize the structural heterogeneity related to plastic flow, (2) probe the dynamics of micro-structure evolved in plastic flow, (3) develop the structure-involved constitutive theory with clear physical meaning, (4) and finally reveal the underlying mechanism for plastic flow, by using a combination of experiments, numerical simulations and theoretical analysis. The present research is very useful for not only enriching the classical plasticity mechanics, but also improving further engineering exploitation of amorphous alloys.

非晶态合金作为先进结构材料已经在国防、空天等领域显示出广阔的应用前景。非晶态合金内部原子排列长程无序，没有位错、晶界等传统意义上的晶体缺陷，因此，基于位错、孪生等机制的经典塑性理论在描述这类材料的塑性行为时遇到了极大的挑战。目前，人们对非晶态合金材料塑性流动的微结构起源与物理机制的认知还十分缺乏。为此，本项目拟以实验研究、数值模拟和理论分析相结合，系统深入地研究与塑性流动密切相关的材料结构非均匀性；捕捉和表征塑性流动过程中材料微结构的演化动力学行为；最后发展以微结构信息为内变量具有明确物理含义的非晶态合金塑性本构理论，揭示这类原子无序材料的塑性流动机理。本项目的研究将丰富和发展塑性力学的经典理论，为推进非晶态合金材料的工程应用提供有益的参考价值。

非晶态合金作为先进结构材料已经在国防、空天等领域显示出广阔的应用前景。非晶态合金内部原子排列长程无序，没有位错、晶界等传统意义上的晶体缺陷，因此，基于位错、孪生等机制的经典塑性理论在描述这类材料的塑性行为时遇到了极大的挑战。为此，本项目以实验研究、数值模拟和理论分析相结合，系统深入地研究了非晶合金从原子尺度到纳米尺度的非均匀结构，及其在弹塑性变形过程中的演化规律；非晶塑性流动的应变率、温度和剪胀效应；发展了原子尺度自由体积与纳米尺度剪切转变相互作用的非晶塑性本构模型。此外，还发现了非晶断裂过程中裂尖塑性流动的Kelvin-Helmholtz动力学失稳，以及基于非晶塑性流动的爆炸焊接技术。本项目的研究将丰富和发展塑性力学的经典理论，为推进非晶态合金材料的工程应用提供有益的参考价值。