报告地点：动力与机械学院报告厅

报告时间：11月23日（周五）上午9：30

邀请人：万亮特聘副研究员

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报告摘要：

Hydrogen in steel is associated with a catastrophic failure mode, known as hydrogen embrittlement. This phenomenon is abrupt and is initiated at the atomic level. Although the exact mechanisms of this phenomenon are still subject to debate [1], some mitigation strategies are available, including minimizing hydrogen ingress with surface coatings, or controlling hydrogen diffusion within via the introduction of microstructural ‘traps’, e.g. second phase precipitates [2]. It is believed that the incorporation of fine, well-distributed traps can reduce the mobility of detrimental hydrogen solute and its penetration toward the susceptible region hence can mitigate the macroscale embrittlement. However, as hydrogen is difficult to examine at fine scale, the experimental evidence is lacking for further optimisation of the microstructural design. Herein we show how atom probe tomography (APT) combined with electrochemical charging can yield hydrogen-trapping data in association with fine V-Mo-Nb carbide traps in a ferritic matrix at the atomic scale [3].It is found that the hydrogen signal is spatially correlated to the locations of the carbide shown by vanadium signal. This correlation verifies the predicted hydrogen trapping phenomenon. More importantly, the accumulative analysis from all the hydrogen distributions in the carbides indicates that the hydrogen is trapped at the inside of the carbide, which provides insight to alloy engineers for the future design of hydrogen resistant microstructure.

[1] I.M. Robertson,et al.,Metall Mater Trans B,46a, 2323-2341 (2015).

[2] H. Bhadeshia,ISIJ International,56, 24-36 (2016).

[3] Y.-S. Chenet al.,Science,355,2323-2341 (2017).

报告人简介：

Dr. Yi-Sheng (Eason) Chen（陈翊�N博士）

Dr. Yi-Sheng Chen graduated with a BSc degree in Materials Science in 2007 and a MSc degree in Materials Science in 2009, both from National Tsing Hua University in Taiwan. After finishing his master study in ceramic powder processing for electronic capacitor application with Prof. Jau-Ho Jean, Eason worked in consulting business for many years before going back to pursue his research career in Academia Sinica Taiwan with Prof. Ing-Shouh Hwang in 2013. He learned the fundamental of field emission science there and then moved on to his doctoral research at University of Oxford with Prof. Michael Moody in 2014. He is now a Sydney Research Fellow in both Australian Centre for Microscopy and Microanalysis (ACMM) and School of Aerospace, Mechanical and Mechatronic Engineering (AMME) of the University of Sydney with Prof. Julie Cairney.