摘要
纯 Ni在透射电镜(TEM)中原位拉伸时,裂纹尖端首先发射大量位错,平衡时形成无位错区,微裂纹在裂纹顶端连续形核或在无位错区中不连续形核,并且形核后将钝化成孔洞或缺口.利用特殊的恒位移加载台,可在TEM中原位研究充氢前后恒位移试样裂尖位错组态的变化.结果表明,氢能促进位错的发射、增殖和运动 和未充氢纯Ni相比,充氢试样在更低的外应力下位错就会发射和运动,当氢促进的位错发射和运动到临界条件时就会使氢致裂纹形核、扩展,导致低应力脆断.
In situ tensile test in TEM showed that a dislocation-free zone (DFZ) formed ahead of a loaded crack tip when dislocation emission and motion reached equilibrium under keeping constant displacement, and a microcrack initiated after the dislocation emission and motion developed to a certain condition through increasing load. A constant deflection device designed for use within TEM was used to investigate the change in dislocation configuration ahead of a loaded crack tip before and after hydrogen-charging and crack initiation during charging under constant displacement. The results showed that hydrogen could enhance dislocation emission, multiplication and motion. A hydrogen-induced crack would initiate during charging under constant displacement when the hydrogen-enhanced dislocation emission and motion developed to a critical condition.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2001年第9期911-916,共6页
Acta Metallurgica Sinica
基金
国家重大基础研究规划项目 G19990650
国家自然科学基金项目 50071010资助
关键词
氢致开裂
透射电镜
位错发射
位错运动
镍
nickel
hydrogen-induced cracking
TEM
dislocation emission and motion