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SCIE SCOPUS
Containerless Processing of the Undercooled Metallic Melts - Overview
Yong Jin KIM
UCI I410-ECN-0102-2009-580-007110240

Brief overview of current containerless electrostatic levitation processing technique and research progress of the area of bulk metallic glass formation is introduced. Undercooling behavior during solidification of the bulk metallic glass forming Zr412Ti13.8Cu12.5Ni10.0Be22.5 alloy has been studied using the containerless electrostatic levitation processing technique. The melt is successfully undercooled to the glass transition temperature forming the amorphous phase with the proper thermal treatment. Differential scanning calorimetry (DSC) is used to determine the Gibbs free energy difference between the crystal and the undercooled liquid. The results indicate that the Gibbs free energy difference between the metastable undercooled liquid and the crystalline solid of the Zr412Ti13.8Cu12.5Ni10.0Be22.5 alloy is relatively small compared to that of conventional metallic glass forming binary alloys even for large undercoolings. The hemispherical total emissivity of undercooled liquid is measured in the whole region of undercooled liquid state. Due to the combining effects of excellent thermal stability of the undercooled liquid in the Zr412Ti13.8Cu12.5Ni10.0Be22.5 alloy with unique experimental technique of the containerless electrostatic levitation processing, it is possible to construct the complete time-temperature-transformation (TTT) diagram. The measured TTT diagram exhibiting the expected "C" shape can not be satisfactorily explained by the existing models due to the complex crystallization mechanisms.

[자료제공 : 네이버학술정보]
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