EAGER: Constitutive Relations in Amorphous Metals

这个早期概念探索性研究基金（EAGER）项目的研究目标是阐明非晶金属的基本机制和本构关系。非晶玻璃或金属玻璃是一种没有长程平动有序的结构无序固体。这种拓扑无序导致了这类材料的一些最显著的机械性能。在过去的十年中，人们进行了大量的研究和开发，以获取其性能，特别是力学性能，从而产生了几种本构关系。然而，这些关系既存在概念上的困难，又缺乏关键的实验支持。具体而言，本文将对两种本构模型进行检验：一种是基于德鲁克-普拉格准则和过渡状态理论的本构模型；第二种是关于可塑性的新理论，是基于自由能的方法。规划了有限元和原子建模两种方法。本研究的最终目标是建立非晶态固体的应力、应变、应变速率、温度与各种物理、结构性能和成分变化之间的本构关系，这是迄今为止尚未存在有效本构模型的材料力学的剩余前沿之一。这项工作不仅将帮助科学界更接近金属玻璃的物理合理和有效的本构模型，而且还将使该领域进一步向拓扑无序固体的变形公式迈进一步。因此，这一努力有望促进固体力学领域的进步。相关的教育计划将与拟议的工作协同结合。

The research objective of this EArly-concept Grant for Exploratory Research (EAGER) project is to elucidate the fundamental mechanisms and constitutive relations in amorphous metals. Amorphous or metallic glass is a structurally disordered solid without the long-range translational order. This topological disorder leads to some of the most remarkable mechanical properties for this class of materials. In the past decade, extensive research and development have been done to harvest the properties, especially the mechanical properties, which led to several constitutive relations. However, these relations suffer from both conceptual difficulties and lack of critical experimental support. In particular, two constitutive models are going to be tested: one is based on Drucker-Prager criterion and transition state theory; and the second, a new theory for plasticity, is the free energy-based approach. Both FEM and atomistic modeling are planned. The ultimate goal of this research is to establish the constitutive relations among stress, strain, strain rate, temperature, and various physical, structural properties and compositional changes for amorphous solids, which is one of the remaining frontiers in mechanics of materials where no working constitutive model exists to date. This exercise will not only help the scientific community to get closer to more physically justified and working constitutive models for metallic glasses, but will also bring the field a step further toward formulation of deformation in topologically disordered solids in general. Thus this effort is expected to contribute to advancements in the area of mechanics of solids. Associated educational plans will be synergistically integrated with the proposed work.