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几十年来,人们对金属的氢致损伤问题的研究主要集中于金属的宏观力学性能和半微观性能。本文用正电子湮没技术研究氢对金属中小到原子尺度的微观结构的影响。 选用纯度99.99％的铁样品八对,经840℃、1.5小时真空退火后电解充氢,充氢电流密度分别为0、2、4、8、16、32、64、256(mA/cm~2),放置19小时后在室温下测量各样品的正电子寿命谱,实验结果用Positronfit程序进行三寿命分量的自由拟合,结果发现,所有充氢样品的平均正电子寿命τ_M和第二寿命成份的相对强度I_2都大于未充氢样品,并且随着充氢电流密度的增大而增大,说明铁中的氢可以引起微观缺陷浓度的显著增大。根据第二寿命成份的寿命值I_2(230～270ps),可以推知新增加的缺陷主要是各种空位,位错和微孔洞。
For decades, the study of hydrogen-induced damage to metals has focused mainly on the macroscopic and semi-microscopic properties of metals. In this paper, the positron annihilation technique was used to study the effect of hydrogen on the microstructure of metal from small to atomic scale. Eight pairs of iron samples with purity of 99.99% were selected. After vacuum annealing at 840 ℃ for 1.5 hours, the samples were electrolyzed and charged with hydrogen. The current density of hydrogen charging was 0, 2, 4, 8, 16, 32, 64, 256 ). After 19 hours of storage, the positron lifetime spectrum of each sample was measured at room temperature. The results of the experiment were used to perform free fitting of the three-life components by the Positronfit program. As a result, it was found that the average positron lifetime τ_M and the second lifetime component The relative intensities of I_2 and I_2 are both larger than that of non-hydrogenated samples, and increase with the increase of hydrogen charging current density, indicating that hydrogen in iron can cause a significant increase in the concentration of micro-defects. According to the life of the second life component I_2 (230 ~ 270ps), it can be deduced that the newly added defects are mainly various vacancies, dislocations and micropores.