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针对纳晶金属材料的氢脆问题,该文提出一个新的理论模型。在该模型的理论框架内,认为堆积在距裂纹尖端最近晶界上的氢原子会阻止位错从裂纹尖端的发射,从而抑制裂纹的钝化,同时促进纳晶金属材料的脆性断裂。该文在有氢和无氢两种条件下,对纳晶镍的临界应力强度因子与晶粒尺寸之间的相互关系进行了对比。结果表明:由于氢原子的脆化作用,纳晶镍的临界应力强度因子下降30%之多,这种氢致纳晶金属材料脆化的现象随其晶粒尺寸的变小而愈加显著。
Aiming at the hydrogen embrittlement problem of nanocrystalline metal, a new theoretical model is proposed. In the theoretical framework of this model, it is considered that the hydrogen atoms deposited on the grain boundary nearest to the crack tip will prevent the dislocation from emitting from the crack tip, thus inhibiting the passivation of the crack and promoting the brittle fracture of the nanocrystalline metal material. In this paper, the relationship between the critical stress intensity factor of nanocrystalline nickel and the grain size is compared under hydrogen and hydrogen-free conditions. The results show that due to the embrittlement of hydrogen atoms, the critical stress intensity factor of nanocrystalline nickel decreases by as much as 30%. The embrittlement of hydrogen induced nanocrystalline metallic materials becomes more and more pronounced with the decrease of grain size.