非晶态固体的结构可以决定性能吗?  

DOES STRUCTURE DETERMINE PROPERTY IN AMORPHOUS SOLIDS?

作　　者：王云江 魏丹 韩懂 杨杰 蒋敏强[1,2] 戴兰宏 Wang Yunjiang;Wei Dan;Han Dong;Yang Jie;Jiang Mingqiang;Dai Lanhong(State Key Laboratory of Nonlinear Mechanics,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China;School of Engineering Science,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院力学研究所非线性力学国家重点实验室,北京100190 [2]中国科学院大学工程科学学院,北京100049

出　　处：《力学学报》2020年第2期303-317,共15页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金(11672299,11972345,11790292);国家重点研发计划(2017YFB0702003,2017YFB0701502);中国科学院青年创新促进会(2017025)资助项目。

摘　　要：晶态固体的力学性能与塑性变形主要由结构缺陷,比如位错的运动决定.而在非晶态固体中结构如何决定性能,仍然是固体力学、材料学和凝聚态物理学共同关心但尚未解决的核心问题之一.传统材料学研究的经典范式为"结构决定性能".遵循这一信条,已经有大量的实验表征与理论、模拟研究,尝试将非晶态固体的某种结构特征与性能建立一一对应关系.但是,科学界对于非晶固体结构-性能关系成立与否,以及背后隐藏的规律知之甚少.本文针对非晶态固体的变形机制以及其微结构特征,基于分子动力学模拟,定量评估短程简单结构与中长程复杂结构在决定非晶态固体动力学性能方面的效用.通过海量抽样每种具体玻璃结构的激活能(标识激发难易程度),尝试将结构参数与激活能建立定量关系,从而揭示出非晶态固体结构-性能关系的隐藏主控因素为结构的空间关联,受限比几何结构本身更关键.只有某种结构在空间上呈现亚纳米级的空间关联长度,这种完备结构才有可能有效地决定非晶态固体的力学性能,而短程简单结构则无效.进一步,给出了评价非晶态固体结构预测性能有效性的普适定量方法,为建立广义无序物质的结构-性能关系提供了筛选准则.The mechanical properties and plastic deformation mechanisms of crystalline solids are mainly determined by their structural defects, e.g., the motion of the versatile dislocations. However, how structures determine properties in non-crystalline solids remains as a major unsolved issue in both solid mechanics, materials sciences, as well as condensed matter physics. Structure determines property is the traditional paradigm of materials science. Following this rule, there are vast experimental characterizations, theoretical studies, and computer simulations appeared in the literature, trying to establish a one-to-one correspondence between a specific structural feature with a unique dynamic property in the general amorphous solids. However, up to date, people gain very little understanding of the structure-property relationships in amorphous solids, not to mention whether there exists any hidden rule behind the structure-property relationships. For this purpose, we focus on the unique features of deformations mechanisms in amorphous solids as well as their microstructure characteristics. Thorough proper samplings of the activation energies of the excitation of these structural parameters by an advanced molecular dynamics technique, we are trying to quantitatively assess the validity of simple short-range structures and medium-to long-range structures in determination of their properties. This is done by examination of the possible correlation between parameters of structures with their activation energies, which implies the level of difficulty in activation of the events. By this we find that the hidden governing rule of structure-property relationship in amorphous solids involves a critical role of spatial autocorrelation length of the specific structural parameter. Constraint is more relevant than geometry itself. If only one structural descriptor presents spatial autocorrelation length up to sub nanometer level, it might effectively predict the mechanical property of amorphous solids;otherwise, the short-range

关 键 词：非晶态固体 结构-性能关系 激活能 玻璃结构 

分 类 号：O344.4[理学—固体力学]