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.
