CERN (European Council for Nuclear Research), CH-1211, Geneva 23, Switzerland.
Multi-Beam Laboratory for Engineering Microscopy, Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, United Kingdom.
Sci Rep. 2018 Jan 25;8(1):1574. doi: 10.1038/s41598-018-19900-2.
Strain is a crucial measure of materials deformation for evaluating and predicting the mechanical response, strength, and fracture. The spatial resolution attainable by the modern real and reciprocal space techniques continues to improve, alongside the ability to carry out atomistic simulations. This is offering new insights into the very concept of strain. In crystalline materials, the presence of well-defined, stable atomic planes allows defining strain as the relative change in the interplanar spacing. However, the presence of disorder, e.g. locally around defects such as dislocation cores, and particularly the pervasive atomic disorder in amorphous materials challenge existing paradigms: disorder prevents a reference configuration being defined, and allows strain to be accommodated in a different manner to crystalline materials. As an illustration, using experimental pair distribution function analysis in combination with Molecular Dynamic (MD) simulations, we highlight the importance of bond angle change vs bond stretching for strain accommodation in amorphous systems.
应变是评估和预测材料力学响应、强度和断裂的关键度量。现代实空间和倒易空间技术的空间分辨率不断提高，同时也具备了进行原子模拟的能力。这为应变的概念提供了新的见解。在晶体材料中，存在着明确、稳定的原子面，因此可以将应变定义为层间距的相对变化。然而，无序的存在，例如局部缺陷（如位错核心）周围，以及非晶材料中普遍存在的原子无序，挑战了现有范式：无序阻止了参考构型的定义，并以与晶体材料不同的方式来适应应变。例如，我们使用实验的配分函数分析结合分子动力学（MD）模拟，强调了在非晶体系中，键角变化与键拉伸对于应变适应的重要性。
