非晶态NiCrFeSiB合金蚀孔萌生期间的电流波动

用电位慢扫描法研究了两种不同含Ｃｒ量的非晶态ＮｅＣｒＦｅＳｉＢ含金在氯化钠溶液中小孔腐蚀萌生期间的电流波动行为．电流波动与亚稳小孔的形成及再钝化过程有关，ＮａＣｌ浓度升高导致亚稳孔形核速度增大及生长速度加快，电极电位升高也使亚稳孔生长速度加快．含Ｃｒ量较低（７ｗｔ％）的合金与含Ｃｒ量较高（１３ｗｔ％）的合金相比，亚稳孔的形核速度和生长速度均较快，孔蚀破坏电位Ｅｂ较负，且随机性更大．亚稳孔的寿命分布大体上服从威布尔概率分布，低Ｃｒ合金正稳孔的电量分布较集中，未观察到较大的亚稳孔；而高Ｃｒ合金上亚稳孔的电荷量分布范围较大，可以出现少数较大的亚稳孔，表明低Ｃｒ合金上亚稳孔转变为稳定蚀孔所对应的临界尺寸较小．讨论了正稳孔的生长与稳定蚀孔形成之间的关系．

CURRENT FLUCTUATIONS DURING PIT INITIATION ON NiCrFeSiB AMORPHOUS ALLOYS

The current fluctuations during pit initiation of two NiCrFeSiB amorphous alloy with different Cr contents in neutral NaCl solutions were investigated using slow potential scanning method. Each curreat fiuctustion gives the information of formation and repassivtion of a single metastable pit. The increase of NaCl concentration in solution resulted in increases of nucleation and growth rates of these metedable pits. The growth rate of the pity was for accelerated by increased potential. AS compared with the alloy of higher Cr content, the nucleation and growth of methetable pits for the low Cr alloy were faster,and its pitting breakdown potential Eb was more cathodic and scattered in a wider potential range. On the average, Q values, the charge quantities calculated from peaks and duration of curreat fluctuation of metastable pits were smaller for the lower Cr alloy than those for the higher Cr alloy, suggesting a sxualler critical she for a metastable pit to grow into a stable one in the former case. The life time of metastable pits followed Weibull probability distribution. The relation between nucleation of metastable pits and growth of stable pits was discussed.