Date of Award
6-1-2016
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Mechanical Engineering
First Advisor
Robert Marks
Second Advisor
Robert Marks
Abstract
In recent years, nano-materials have been a popular direction of research in the field of materials science. Nanocrystalline aluminum has been of particular intrest among the nano-materials. This thesis describes the results of three-dimensional molecular dynamics simulations that have been performed to study grain growth in nanocrystalline FCC aluminum. This project built the models by using the Voronoi geometry method to study the grain growth mechanism, grain boundary structure and the effects of temperature and grain size on the crystal structure and grain growth by Energy Analysis, Radial Distribution Function (RDF) analysis, and investigating changes in Centro symmetric parameters.
The results show that nanocrystalline grains are organized and have low energy, whereas grain boundaries consist of distorted regions. The grain growth is controlled by curvature driven grain boundary migration. By analyzing the effect of the temperature and grain size on grain growth, the rate of grain growth increases with increasing temperature. The grain boundary mobility increases with increasing grain size. Grain boundary mobility refers to how easily grain boundaries move, and the grain growth rate is the product of mobility and a driving force term, the later which is inversely proportional to grain size. When the sizes of grains are approximately equal, the curvature direction of initial grain boundary will determine grain growing or shrinking. Grain boundary migration always occurs toward the center of curvature.
Recommended Citation
Yin, Jielong, "Molecular Dynamics Study on the Grain Growth in Nanocrystalline Aluminum" (2016). Mechanical Engineering Master's Theses. 4.
https://scholarcommons.scu.edu/mech_mstr/4