Papers by Author: Ha Guk Jeong

Abstract: Mg alloy sheets exhibit the yield strength of 280 MPa and elongation of 18 % by rolling at 423 K. Elongation of Mg alloy sheets was improved up to 35 % when the sample was annealed at 673 K for 10 min. From the observation of microstructure, recrystallization and grain growth have happened during annealing processes. The intensity of 0002 pole figure increases slightly as a function of annealing temperature.

Abstract: In this study, Al/Cu composite was produced by hydrostatic extrusion process at 523 K. Mechanical and electrical properties of Al/Cu composite were investigated during isothermal aging. Microstructure observation and composition analysis of the interface was carried out scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. Three kinds of intermetallic composites are observed and they have increased in size as a function of annealing process. Their growth brings about the decrease in the hardness Al/Cu composite.

Abstract: MgZn4.3Y0.7 alloy powders were prepared using an industrial scale gas atomizer, followed by warm extrusion. The powders were almost spherical in shape. The microstructure of powders as atomized and bars as extruded was examined as a function of initial powder size distribution using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscope (EDS) and X-ray Diffractometer (XRD). The grain sizes were decreased with extruding as well as decreasing the initial powder sizes. Both the ultimate strength and elongation were enhanced as the initial powder sizes were decreased.