Atom Probe Tomography를 활용한 알루미늄 합금의 나노스케일 특성 분석 = Nanoscale Characterization of Aluminum Alloys Using Atom Probe Tomography

다국어 초록 (Multilingual Abstract)

This study investigates the analysis of solute clustering in Al-Mg-Si-Cu-Sn alloys using atom probe tomography (APT), focusing on the effects of region of interest (ROI) selection and user-defined parameters on data reconstruction and cluster identification algorithms. To minimize analysis errors, the following findings and recommendations are proposed: First, the presence of pole regions in the APT reconstruction significantly impacts cluster analysis results. Analyses excluding these pole regions from the outset (“Partial”) minimize compositional bias caused by Si-surface migration to the pole regions, easily visualized by iso-concentration surfaces, making this the recommended approach. Second, results from fixed sets of parameters for the maximum separation (MS) algorithm for cluster identification were compared with results obtained with parameters optimized for each dataset using comparator data from the random labelling process (RLP). Fixed parameters showed limitations in detecting clusters under varying conditions, while the parameters set by RLP more accurately reflected the atomic distribution. Dmax variability due to randomization affected cluster detection, with overly small Dmax splitting clusters and overly large Dmax misidentifying matrix regions as clusters, emphasizing the need for careful parameter selection. Lastly, spatial normalization was applied to determine the inclusion of Cu and Sn within clusters with sufficient statistical significance. Results showed that Cu is incorporated into clusters, while Sn is excluded. The normalization method is essential for reliable APT analysis, ensuring accurate interpretation of cluster formation and alloying element effects.

목차 (Table of Contents)

• 1. 서론 1
• 2. 이론적 배경 3
• 2.1 Atom Probe Tomograghy, APT 3
• 2.2 kth Nearest Neighbor Distribution, kNND 7
• 2.3 Random Labelling Process, RLP 9
• 2.4 APT에서 매개변수 설정의 중요성 12
• 2.5 Al-Mg-Si-Cu-Sn 합금 14
• 3. 실험방법 15
• 3.1 클러스터 분석을 위한 ROI 선택 방법 15
• 3.2 시편 준비 18
• 3.3 APT 비교 분석을 위한 실험 방법 19
• 4. 실험 결과 및 고찰 22
• 4.1 ROI 설정에 따른 클러스터링 특성 분석 22
• 4.2 사용자 정의 매개변수에 따른 클러스터 분석 28
• 4.3 kNND 분포에서 랜덤데이터 셋이 Dmax 설정에 미치는 영향 37
• 4.4 Dmax가 클러스터 분석에 미치는 영향 44
• 4.5 합금 첨가 원소에 따른 클러스터 분석 52
• 5. 결론 59
• 참고문헌 61