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

金属玻璃基复合材料是一种新型材料，它结合了高强度、非结晶金属和延展性结晶夹杂物。通过结合这两种成分，人们的目标是克服金属玻璃固有的脆性。这些材料在同时达到高强度和高延展性方面具有巨大的潜力。然而，导致金属玻璃基复合材料性能的机制的确切性质仍然未知。充分了解这些机制是充分利用金属玻璃基复合材料的必要条件。本研究将实验与计算模型相结合，研究这些材料独特的变形行为。它的目标是建立新的变形机制图，这是工程师常用的描述材料特性的工具。这些机制的知识将定义新的方法来控制金属玻璃基复合材料的机械性能。这将有能力改变结构金属的经典应用空间，并在现代冶金中开辟令人兴奋的新研究领域。主要调查人员将为代表性不足的大学生提供研究和学习机会。这些学生将被激励去实现他们的个人潜力，同时培养批判性思维技能、学术创造力和对工程的热情。这些活动将在综合计算材料工程方法的背景下进行。本研究的目的是对金属玻璃基复合材料中与剪切带形核和扩展相关的竞争速率以及这些力学对应变离域和延性的影响有一个新的基本认识。指导假设是，由晶相引起的延性是由于剪切带传播速率的限制，这反过来又促进了许多剪切带的形核，从而有效地使塑性应变积累过程脱域。为了验证这一假设，这个多方面的研究项目将独特的中尺度剪切转变区动力学模拟与仪器压痕技术相结合，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的可调机械性能。

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.