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pISSN : 1598-706X / eISSN : 2288-8381


한국주조공학회지 (23권5호 276-285)

In Situ Observation of Solidification Behavior in Undercooled Pd4oCu3oN11oP20 Alloy Melts during Linear Cooling

연속냉각 중 과냉 된 Pd4oCu3oN11oP20 합금 용탕의 실시간 응고거동 관찰

Ji-Hun Kim

Yonsei University


In the undercooled melt of Pd4oCu3oNi IOPZO alloy, the solidification behavior including nucleation and growth of crystals at the micrometer level has been observed in-situ by use of a confocal scanning laser microscope combined with an infrared image furnace. The Pd4oCu3oNi1oP20 alloy specimens were cooled from the liquid state to glass transition temperature, 575 K, at various cooling late under a helium gas flow. According to the cooling rate, the morphologies of the solidification front are changed among various types, irregular jog like front, columnar dendritic front, cellular grain, star like shape jog and fine grain, etc. The velocities of the solid-liquid interface are measured to be lo‘5~lo'3 m/s which are at least two orders higher than the theoretical crystal growth rates. Combining the morphologies observed in terms of cooling rates and their solidification behaviors, we conclude that phase separation takes place in the undercooled molten Pd4oCu3oNi1oP20 alloy. The continuous cooling transfor- mation (CCT) diagram was constructed from solidification onset time at various linear cooling conditions with different rate. The CCT diagram suggests that the critical cooling rate for glassy solidification is about 1.5 K/s, which is in agreement with the previous calorimetric findings.


Metallic glass, Undercooled solidification behavior, In-situ observation, Continuous cooling transformation (CCT)