Collaborative Research: Elucidating the Mechanics of Shear Delocalization in Metallic Glass Matrix Composites

金属玻璃基复合材料是一类新型材料，它将高强度非晶金属与延展性结晶内含物结合在一起。通过将这两种成分结合起来，旨在克服金属玻璃固有的脆性。这些材料具有同时达到高强度和高延展性的巨大潜力。尽管如此，金属玻璃基复合材料性能机制的确切性质仍然未知。要充分利用金属玻璃基复合材料，需要充分了解这些机制。这项研究结合了实验和计算模型来研究这些材料的独特变形行为。它的目标是构建新的变形机制图，这是工程师常用来描述材料属性的工具。了解这些机制将定义控制金属玻璃基复合材料机械性能的新方法。 这将改变结构金属的经典应用空间，并开辟现代冶金研究的令人兴奋的新领域。主要研究人员将为代表性不足的大学生提供研究和学习机会。这些学生将被激励实现个人潜力，同时培养批判性思维技能、学术创造力和对工程的热情。此类活动将在集成计算材料工程方法的背景下进行。这项研究的目的是对与金属玻璃基复合材料中剪切带成核和传播相关的竞争速率以及这些力学对应变离域和延展性的影响有一个新的基本理解。指导性假设是，结晶相引起的延展性是由于剪切带传播速率的限制而产生的，这反过来又促进了许多剪切带的成核，从而有效地使塑性应变积累过程离域。为了检验这一假设，这个多方面的研究计划将独特的中尺度剪切转变区动力学模拟与仪器化压痕技术相结合，以检查导致离域的速率竞争以及出现的任何自然长度尺度。通过将速率和机械长度尺度与微观结构变量相关联，将构建新的变形机制图，以阐明离域机制并制定新的设计方法，以实现金属玻璃基复合材料中可调节的机械性能。

Metallic glass matrix composites are a new class of materials that combine high-strength, non-crystalline metals with ductile crystalline inclusions. By combining these two components one aims to overcome the inherent brittleness of metallic glasses. These materials have a tremendous potential to reach both high strength and and high ductility at the same time. Still, the exact nature of the mechanisms responsible for the properties of metallic glass matrix composites remains unknown. A full knowledge of these mechanisms is needed to fully use metallic glass matrix composites. This research combines experiments and computational modeling to study the unique deformation behavior of these materials. It has the goal to build new deformation mechanism maps, a tool commonly used by engineers to depict material properties. Knowledge of these mechanisms will define new methods to control the mechanical properties of metallic glass matrix composites. This will result in the ability to transform the classical application space of structural metals and open up exciting new areas of research in modern metallurgy. The principle investigators will offer research and learning opportunities for underrepresented college students. These students will be motivated to achieve their individual potential while fostering the development of critical thinking skills, academic creativity, and a passion for engineering. Such activities will be in the context of the Integrated Computational Materials Engineering approach.The objective of this research is to develop a new fundamental understanding of competing rates associated with shear band nucleation and propagation in metallic glass matrix composites and the implications of these mechanics for strain delocalization and ductility. The guiding hypothesis is that the ductility induced by the crystalline phase results from the limitation of shear band propagation rates, which in turn promotes the nucleation of many shear bands that effectively delocalizes the process of plastic strain accumulation. To test the hypothesis, this multifaceted research program combines unique mesoscale shear transformation zone dynamics simulations with instrumented indentation techniques for examining the competition of rates leading to delocalization as well as any natural length scales that emerge. By correlating rates and mechanical length scales to microstructural variables, new deformation mechanism maps will be constructed to elucidate the mechanics of delocalization and formulate new design methodologies for enabling tunable mechanical properties in metallic glass matrix composites.