2원계 Fe-Cr 및 Fe-Ni합금에서 고속 셀의 형성거동 연구 = Formation of High Velocity Cells in Fe-Cr and Fe-Ni Alloys

다국어 초록 (Multilingual Abstract)

During directional solidification of alloys, transitions from a planar to cell to dendrites generally occur as the velocity is increased. The reverse transition from dendrites to cell also occurs when the velocity is increased further. The high velocity transition is generally observed in rapid solidification techniques. In this study, experiments have been carried out in Fe-Cr and Fe-Ni in which the freezing range is very narrow so that the high transition occurs at relatively low velocities, 50~100㎛/sec, by bridgman-type directional solidification. We observed that dendrite formation can be suppressed so that the interface of solid/liquid changes continuously from low velocity to high velocity cell. It was also interesting to find that the cell spacing was continuous with growth velocity from the low and high velocity cells. The interface temperature analysis by using the cellular growth model. Interface temperature increases with velocity for the low velocity cell whereas is decreases with velocity for the high velocity cell.

목차 (Table of Contents)

• 1장. 서론 = 1
• 2장. 이론적 배경 = 3
• 2.1 합금이 고/액 계면형상의 변화 = 3
• 2.2 일방향 응고 = 5
• 3장. 실험방법 = 7
• 3.1 시편준비 = 7
• 3.2 일방향 응고 실험 = 7
• 3.3 온도 구배 측정 = 11
• 3.4 미세조직관찰 = 11
• 4장. 실험결과 = 13
• 4.1 평형 상태도 예측 = 13
• 4.2 고/액 계면의 형상 = 15
• 4.3 1차 수지상 간격 = 19
• 5장. 고찰 = 21
• 5.1 고속 셀 현상 = 21
• 5.2 고/액 공존구간이 Vcr, Va 에 미치는 영향 = 28
• 5.3 저속셀과 고속셀의 수지상 간격 = 30
• 5.4 고/액 계면온도 = 33
• 6장. 결론 = 39
• 7장. 참고문헌 = 40
• Abstract = 41
• Appendix = 42