摘要
与绝大多数材料遵循基于位错攀移的指数蠕变机制不同,多晶冰遵循基于位错滑移的指数蠕变机制,这种机制引起了冰川学家极大的兴趣.以前人的研究为基础,综述了冰中质子无序及质子点缺陷的形成过程,质子点缺陷对位错滑移影响的微观机理,以及多晶冰蠕变的微观机制.研究表明:冰晶体中的氢原子(质子)无序使得位错在滑移过程中形成质子点缺陷(D、L、H3O+和OH-缺陷),从而降低了位错的滑移速率.质子点缺陷的形成需要氢原子(质子)跃迁,其激活能大于水分子自扩散所需的激活能.同时,多晶冰的蠕变激活能与质子跃迁的激活能相当,而大于水分子自扩散所需的激活能,因此多晶冰的蠕变控制机制是位错滑移,而不是位错攀移.
Unlike most materials, in which the dislocation climb is the controlling mechanism for exponent creep behavior, the controlling mechanism for exponent creep behavior of polycrystalline ice is dislocation glide. The mechanism attracts lots of interests from many glaciologists. This paper reviews the formation of the proton disorder and protonic point defects, the effect of the protonic point defects on dislocation glide, and the micro-mechanics of creep in polycrystalline ice. The results from previous studies indicated that the protonic point defects （D^-, L^-, H3O^＋ and OH^--defects） have been formed during dislocation glide due to the hydrogen （proton） disorder in ice crystals, which decreases the velocity of dislocation glide. The formation of protonic point defects need hydrogen （protons） jumping and its activation energy is higher than that for the self-diffusion of water molecules. Since the activation energy for creep is close to the activation energy for proton jumping and higher than that for the self-diffusion of water molecules, the rate-controlling mechanism for creep is dislocation glide instead of dislocation climb.
出处
《冰川冻土》
CSCD
北大核心
2007年第3期482-486,共5页
Journal of Glaciology and Geocryology
基金
美国国家自然科学基金(National Science Foundation)极地科学研究部项目(OPP011737)资助
关键词
蠕变
位错
质子无序
质子点缺陷
creep
dislocation
proton disorder
protonic point defects
