Papers by Author: Deok Soo Kim

Abstract: The aging behavior of sintered Al composites with various ceramic contents was investigated. 2xxx series blended powder was used as the starting powder. Ceramic contents were 0 wt.% and 5 wt.%. The blended powders were compacted at 250 MPa. The sintering process was performed at 620oC for 60 min in a N2 atmosphere. After sintering, each part was solution-treated at 518oC for 60 min and aged at 180oC. The Rockwell hardness value at the peak aging time increased with increased ceramic contents. However, the peak aging time at maximum hardness was reduced with increased ceramic contents. The changes in aging behavior may have been caused by the acceleration of diffusion due to the strain induced by differences in the thermal expansion coefficients of the matrix and the ceramic phases.

Abstract: The structural configurations of atom constituting materials are one of the fundamental factors in the study of physical properties of materials. Presented in this paper is a mathematical and computational methodology to efficiently classify a given atomic structure of an arbitrary material into groups of atoms in BCC, FCC, and HCP crystal structures. The approach is based on the angle distributions among neighboring atoms efficiently identified by a computational geometry technique called Voronoi diagram. In this paper, the presented mathematical theory was applied to analyze a multi-layer atomic structure in a geometric perspective so that a best condition for thin film growth can be found.