• 한국분말재료학회지
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• 제19권1호
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• pp.67-71
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• 2012

The present paper gives an overview about the Atom Probe Tomography technique and its application to powder materials. The preparation of needle-shaped Atom Probe specimens from a single powder particle using focused-ion-beam milling is described. Selected experimental data on mechanically alloyed (and sintered) powder materials are presented, giving insight into the atomic-scale elemental redistribution occurring under powder metallurgical processing.

• Applied Microscopy
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• 제46권3호
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• pp.127-133
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• 2016

Atom probe tomography is a time-of-flight mass spectrometry-based microanalysis technique based on the field evaporation of surface atoms of a tip-shaped specimen under an extremely high surface electric field. It enables three-dimensional characterization for deeper understanding of chemical nature in conductive materials at nanometer/atomic level, because of its high depth and spatial resolutions and ppm-level sensitivity. Indeed, the technique has been widely used to investigate the elemental partitioning in the complex microstructures, the segregation of solute atoms to the boundaries, interfaces, and dislocations as well as following of the evolution of precipitation staring from the early stage of cluster formation to the final stage of the equilibrium precipitates. The current review article aims at giving a comment to first atom probe users regarding the limitation of the techniques, providing a brief perspective on how we correctly interprets atom probe data for targeted applications.

• Applied Microscopy
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• 제41권2호
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• pp.89-98
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• 2011

Atom Probe Tomography는 원자 수준의 분해능으로 원소의 위치 및 조성 정보를 3차원으로 제공해 주는 분석 장비이다. APT의 우수한 성능에도 불구하고 반도체 등, 저전도성 물질 분석에는 그 동안 적용이 어려웠다. 그러나 특정 시료 내 위치의 시편을 가공할 수 있는 FIB 시편 제조법과 laser펄스를 이용한 전계증발법의 개발로 APT의 분석 영역이 반도체에서 절연체까지 크게 확대 되고 있다. 본 논문에서는 최근에 적용되기 시작한 MOS-FET, GaN LED, Si-Nanowire 등 전자소자에서의 APT분석 응용사례에 대하여 살펴보았다.

• Applied Microscopy
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• 제41권2호
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• pp.81-88
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• 2011

최근 나노 영역에서의 구조분석과 조성분석의 중요성이 증대되고 있으나, 기존의 분석장비들은 한계에 부딪히고 있다. 최근 개발된 APT는 nm 이하의 공간분해능과 수십 ppm수준의 detection limit으로 원소의 3차원분포와 조성정보를 제공해 주는 분석장비로서, 이러한 기존 분석의 한계를 극복할 수 있는 새로운 분석장비이다. 그러나 국내에는 아직 잘 알려지지 않아 활용이 미비한 실정이다. 따라서, 본 논문에서는 APT에 대한 이해를 돕기 위해 APT분석의 원리와 시편준비에 대해 소개하였다.

• Applied Microscopy
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• 제46권3호
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• pp.117-126
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• 2016

Atom probe tomography (APT) has been fast rising in prominence over the past decade as a key tool for nanoscale analytical characterization of a range of materials systems. APT provides three-dimensional mapping of the atom distribution in a small volume of solid material. The technique has evolved, with the incorporation of laser pulsing capabilities, and, combined with progress in specimen preparation, APT is now able to analyse a very range of materials, beyond metals and alloys that used to be its core applications. The present article aims to provide an overview of the technique, providing a brief historical perspective, discussing recent progress leading to the state-of-the-art, some perspectives on its evolution, with targeted examples of applications.

• Applied Microscopy
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• 제43권3호
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• pp.122-126
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• 2013

The heterogeneous nucleation of the ${\Theta}^{\prime}$ phase on nanoscale precipitates has been investigated using a combination of three-dimensional atom probe tomography and high-resolution transmission electron microscopy. Two types of ${\Theta}^{\prime}$ phases were observed, namely small (~2 nm thick) cylindrical precipitates and larger (~100 nm) globular precipitates and both appear to be heterogeneously nucleated on the nanoscale precipitates. The composition and crystal structure of precipitates were directly analyzed by combination of two advanced characterization techniques.

• Applied Microscopy
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• 제46권1호
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• pp.14-19
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• 2016

Currently, focused ion beams (FIB) are widely used for specimen preparation in atom probe tomography (APT), which is a three-dimensional and atomic-scale compositional analysis tool. Specimen preparation, in which a specific region of interest is identified and a sharp needle shape created, is the first step towards successful APT analysis. The FIB technique is a powerful tool for site-specific specimen preparation because it provides a lift-out technique and a controllable manipulation function. In this paper, we demonstrate a general procedure containing the crucial points of FIB-based specimen preparation. We introduce aluminum holders with moveable pin and an axial rotation manipulator for specimen handling, which are useful for flipping and rotating the specimen to present the backside and the perpendicular direction. We also describe specimen preparation methods for nanowires and nanopowders, using a pick-up method and an embedding method by epoxy resin, respectively.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.91-94
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• 2008

Newly developed Atom Probe Tomography (APT) technique can provide the highest available spatial resolution, 3D tomography imaging and quantitative chemical analysis in a sub-nm scale. As a complementary technique to APT, Nano-secondary ion Mass Spectroscopy (SIMS) also provides the boron distribution in micro-scale. Therefore, the exact behavior of boron at either grain boundary or grain interior in steels can be investigated by the combination of APT and SIMS techniques from the sub-nanometer scale to the micrometer scale. The results obtained by both APT and SIMS revealed that the boron atoms were mainly segregated to the grain boundaries rather than to the grain interior in the steels containing 50ppm and 100ppm boron. It also found that carbon atoms were segregated at the boron enriched regions, which were thought to be retained austenite phase due to the chemical composition of carbon atoms.

• 한국재료학회지
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• 제23권3호
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• pp.190-193
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• 2013

Spatial distributions of alloying elements of an Fe-based amorphous ribbon with a nominal composition of $Fe_{75}C_{11}Si_2B_8Cr_4$ were analyzed through the atom probe tomography method. The amorphous ribbon was prepared through the melt spinning method. The macroscopic amorphous natures were confirmed using an X-ray diffractometer (XRD) and a differential scanning calorimeter (DSC). Atom Probe (Cameca LEAP 3000X HR) analyses were carried out in pulsed voltage mode at a specimen base temperature of about 60 K, a pulse to base voltage ratio of 15 %, and a pulse frequency of 200 kHz. The target detection rate was set to 5 ions per 1000 pulses. Based on a statistical analyses of the data obtained from the volume of $59{\times}59{\times}33nm^3$, homogeneous distributions of alloying elements in nano-scales were concluded. Even with high carbon and strong carbide forming element contents, nano-scale segregation zones of alloying elements were not detected within the Fe-based amorphous ribbon. However, the existence of small sub-nanometer scale clusters due to short range ordering cannot be completely excluded.

• Nuclear Engineering and Technology
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• 제44권6호
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• pp.673-682
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• 2012

Three dimensional atom probe tomography (3D APT) is applied to characterize the dissimilar metal joint which was welded between the Ni-based alloy, Alloy 690 and the low alloy steel, A533 Gr. B, with Alloy 152 filler metal. While there is some difficulty in preparing the specimen for the analysis, the 3D APT has a truly quantitative analytical capability to characterize nanometer scale particles in metallic materials, thus its application to the microstructural analysis in multi-component metallic materials provides critical information on the mechanism of nanoscale microstructural evolution. In this study, the procedure for 3D APT specimen preparation was established, and those for dissimilar metal weld interface were prepared near the fusion boundary by a focused ion beam. The result of the analysis in this study showed the precipitation of chromium carbides near the fusion boundary between A533 Gr. B and Alloy 152.