"Mechanical Property Improvement in Metallic Materials via Introduction of Thick Grain Boundaries" 

Lloyd Abramic, MSE PhD Candidate 

Advisor: Professor Xinghang Zhang

ABSTRACT

Metallic materials, specifically thin films and coatings, are essential components of modern technologies such as microelectronics, corrosion and wear-resistant coatings, solar cells, and batteries. The constant drive to downsize these devices necessitates smaller films with equal or superior mechanical properties. Grain boundary engineering has proven to be one method of improving these properties, specifically tailoring the thickness of the boundaries. The classical definition of grain boundaries in polycrystalline materials regards them as near-two-dimensional phases 1-2 atomic layers thick that may also be considered as complexions between grains. In contrast, thick grain boundaries (TGBs) are defined as phases between grains with thicknesses from 1-10 nm. The addition of these interfacial features has proven to enhance the mechanical properties and thermal stabilities of metallic materials compared to their counterparts without TGBs. This report discusses the different types of TGBs in metallic materials and their respective mechanisms for mechanical property enhancement. The introduction of TGB-like structures into sputtered multilayer metallic coatings and their strengthening properties will subsequently be discussed.