Understanding Intrinsic Ductility in Metallic Glasses

技术总结该奖项支持计算和理论研究以及教育，以促进对金属玻璃内在延展性的理解。材料失效的条件和方式是工程师和科学家最关心的问题。最近，人们在非晶态固体(包括金属玻璃和氧化物玻璃)中发现了泊松比与断裂能之间的经验关系。然而，对于接近平衡的弹性和远离平衡的破坏之间如此方便和有趣的关联，理论上几乎没有什么理解。PI将使用分子动力学模拟和电势调节相结合的方法来研究金属玻璃作为典型的非晶态固体的本征延展性。这种策略将能够通过规定原子相互作用来探索实验中无法获得的无定形固体。泊松比和断裂能都将从原子成键和堆积的角度进行研究。结构如何决定本征延展性的知识对于使金属玻璃甚至氧化物玻璃变得坚韧至关重要。本项目开发的计算平台可用于进行动态断裂和疲劳试验，以及研究薄膜、多孔材料和复合材料的断裂韧性。在这里获得的见解还将提供将泊松比与致密化、易碎性和玻璃化转变联系起来的其他经验关系的重要线索。PI将通过与伦斯勒理工学院合作的新视野：数学、工程、技术和科学项目，接触对科学和工程感兴趣的高中生。计划的活动包括为期半天的计算材料科学迷你讲座，并辅之以互动演示。PI还将通过继续开发开源可视化软件SimRePlay.NON-TECHIC SUMMARY来接触计算研究社区。该奖项支持计算和理论研究以及了解无定形固体材料如何失效的教育。智能手机的触摸屏由氧化物玻璃制成，在撞击时会破碎，而由金属原子组成的玻璃，即所谓的金属玻璃，可以像钢一样坚硬。PI将使用先进的计算机模拟技术来模拟各种非晶态固体的断裂。从原子水平的计算工作中获得的见解将有助于理解和预测无定形固体的失效模式，并为如何制造坚硬的玻璃提供重要线索。PI将通过与伦斯勒理工学院合作的新视野：数学、工程、技术和科学项目，接触对科学和工程感兴趣的高中生。计划的活动包括为期半天的计算材料科学迷你讲座，并辅之以互动演示。PI还将通过继续开发开源可视化软件SimRePlay来接触计算研究社区。

TECHNICAL SUMMARYThis award supports computational and theoretical research and education to advance understanding of the intrinsic ductility of metallic glasses. The conditions and manner in which materials fail are of fundamental concerns to both engineers and scientists. Recently an empirical relation has been found between the Poisson's ratio and the fracture energy in amorphous solids, including metallic glasses and oxide glasses. However, there is little theoretical understanding for such a convenient and intriguing correlation between near-equilibrium elasticity and far-from-equilibrium failure. The PI will use molecular dynamics simulation coupled with potential-tuning scheme to investigate the intrinsic ductility of metallic glasses, as a prototypical amorphous solid. Such strategy will enable the exploration of amorphous solids unavailable in experiments by prescribing atomic interactions. Both the Poisson's ratio and the fracture energy will be studied in terms of the atomic bonding and packing. The knowledge of how structure determines intrinsic ductility is crucial to toughening metallic glasses and even oxide glasses. The computational platform developed in this project can be used to conduct dynamic fracture and fatigue testings, and to study fracture toughness of thin films, porous materials and composite materials. Insights gained here will also provide important clues on other empirical relations linking the Poisson's ratio to densification, fragility and glass-transition.The PI will reach out to high school students interested in science and engineering through the New Visions: Math, Engineering, Technology & Science program in collaboration with Rensselaer Polytechnic Institute. Planned activities include half-day mini-lectures on computational materials science, complemented with interactive demonstrations. The PI will also reach out to the computational research community by continuing developing open-source visualization software SimRePlay.NON-TECHNICAL SUMMARYThis award supports computational and theoretical research and education to understand how amorphous solid materials fail. The touch screens of smart phones, made of oxide glasses, are brittle as they shatter upon impact, while glasses constituted with metal atoms, termed metallic glasses, can be as tough as steels. The PI will use advanced computer simulation techniques to model the fracture of various amorphous solids. The insights gained from computational work at the atomic level will help understand and predict the failure mode of amorphous solids, and provide important clues of how to make tough glasses.The PI will reach out to high school students interested in science and engineering through the New Visions: Math, Engineering, Technology & Science program in collaboration with Rensselaer Polytechnic Institute. Planned activities include half-day mini-lectures on computational materials science, complemented with interactive demonstrations. The PI will also reach out to the computational research community by continuing developing open-source visualization software SimRePlay.