Mechanical Behavior of Ternary Metallic Glasses and Their Composites

Abstract

The vast demands for advanced materials have been putting tremendous pressure on materials scientists and engineers to discover and produce novel lighter and stiffer materials. This dissertation is devoted to the development and fundamental understanding of the strength and the structures within Aluminum ternary metallic glasses (MGs) and their composites, which have a low density and promising high strength. The dissertation focuses on the following content: The multi-objective optimization algorithm predicted the Al16.5Ni8Ce75.5 ternary metallic glass composition with an improved glass-forming ability (supercooled liquid region ∆����=29K), based on the provided dataset. Inoue Criteria can predict the Al46Ni10Ce44 metallic glass concentration with the highest supercooled liquid region ∆����=40K and best initial hardness 389(Hv). The highest hardness value, 853(Hv), was achieved when annealed Al46Ni10Ce44 at 573K for 30 mins. This value is significantly high compared to the published hardness of bulk MG systems, such as Zr-based, Pd-based and Mg-based metallic glasses, as well as conventional alloys such as stainless steel and super high strength steel. The relationship between the hardness of Al-Ni-Ce MGs and the annealing temperatures was investigated by high energy synchrotron X-ray diffraction (HEXRD) and Transmission Electron Microscopy (TEM). Obtained HEXRD and TEM results and microindentation values show that when the annealing temperature is close to the onset temperature of crystallization, the hardness reaches the highest value.