3-D Atom Probe Tomography and Secondary ion Mass Spectroscopy techniques for the microstructure and atomic scale investigation on the state of Boron in Steels

3차원 원자 침 분석기 (3-DAPT)와 이차이온 질량분석기 (SIMS)을 이용한 보론 첨가 강의 미세구조와 보론의 원자 단위 분석

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.