非晶态结构对锆镍金属玻璃点蚀行为影响的研究

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	非晶态结构对锆镍金属玻璃点蚀行为影响的研究
	王冬朋
学位类型	硕士
导师	王建强
	2012
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	材料学
关键词	金属玻璃非晶态结构单晶点蚀钝化膜 Glass Amorphous Structures Single Crystal Pitting Corrosion Passive Films
摘要	"自从发现非晶态合金具有较高的耐腐蚀能力以来，金属玻璃的腐蚀行为就引起了人们的广泛关注。非晶态结构与合金腐蚀行为关联性研究是理解金属玻璃腐蚀机制的一个基本课题，然而人们对此的认识却非常有限，这已成为全面理解金属玻璃腐蚀机理的严重障碍。为了探索这种结构因素的影响，人们在不同的合金体系里做了大量探索。其中最主要的研究方法是将金属玻璃进行退火晶化处理，比较晶化前后合金腐蚀行为的差异，总结结构因素的作用。但是由于退火会产生晶界、位错、相界等晶体缺陷，而且晶化过程往往会伴随着成分再分布，使得在研究结构作用的同时，通常掺杂着上述因素的影响，难以独立地分离出结构因素的作用。这也使得在不同的体系里得到的结果并不相同。课题选取了既能形成非晶、又能形成单晶的Zr2Ni金属玻璃体系。在成分和结构均匀的条件下，排除了上述因素的影响，独立分离出了结构因素的作用。通过对比所选体系电化学腐蚀行为及钝化膜成分的差异，分析了非晶态结构对合金腐蚀行为的具体影响，并对其中的可能机制进行了探讨。研究结果如下：（1）使用真空光学悬浮熔炼和熔体激冷设备分别制备出单晶态和非晶态Zr2Ni合金样品。动电位极化曲线测试结果显示，与单晶Zr2Ni合金相比，非晶态合金在0.1 M NaCl溶液中自腐蚀电流密度、钝化电流密度较低，表现出较低的腐蚀速度。电化学阻抗谱和Mott-Schottky曲线测试结果显示，非晶态合金表面钝化膜的化学稳定性更高，电荷传递电阻更大，钝化膜中载流子浓度（缺陷程度）较低。恒电位极化曲线结果说明非晶态结构改变了钝化膜的生长机制，使得其表面生成的钝化膜组织更为致密，防护性能更好。（2）非晶态结构通过影响钝化膜的成分改变合金的腐蚀行为。运用XPS技术对不同状态Zr2Ni合金的钝化膜的成分及深度分布进行了测试分析。结果显示，与单晶Zr2Ni合金相比，非晶态合金钝化膜中组织致密的ZrO2含量较高，而组织疏松、耐蚀性较差的NiO含量较低。"
其他摘要	"Since the discovery of the extremely high corrosion resistance of the amorphous alloy, the corrosion behaviour of metallic glasses has caused widespread concern over the world. The relationship between amorphous structure and corrosion behaviour of alloys is a fundamental problem to understand the corrosion mechanism of metallic glasses. However, we have very limited knowledge of this field, and it has long been an obstacle to mechanistic understanding of metallic glasses corrosion behaviour. To solve this long-term puzzling problem, varies reaserches in different alloy systems have been investigated extensively by comparing the corrosion behaviour between amorphous alloys and their crystallised counterparts after heat treatment. It is noted that for most of multi-component metallic glasses, there exist the compositional redistribution and the precipitation of various phases during the crystallisation, as well as some other crystal defects. The differences of the kind, size, and distribution of those crystal defects could cause different effects on the corrosion behaviour. So it is difficult to change the structure independent of composition in most metallic glass systems and there are controversial results in different alloys. In this thesis, a Zr2Ni metallic glass was selected as a model system to understand the above mentioned problem. The equilibrium state of the single crystal also has a componential and structural homogeneity without grain boundaries and second phase particles. So the Zr2Ni alloy is an ideal system to reveal the structural effects on corrosion separating from the chemical composition factor. The effect of amorphous structure on corrosion behaviour and the possible mechanism were analysised by comparing electrochemical properties and composition of passive films for different kinds of samples. The main results are summarized as follows: (1) The single crystal and amorphous alloy samples were prepared separately using an optical floating-zone furnace and melt-spuning. The corrosion behaviour was studied in 0.1 M NaCl solution. It was found that the single crystal Zr2Ni alloy has a lower corrosion resistance with a higher corrosion rate than its amorphous counterpart. The electrochemical measurement demonstrated that passive films formed on the amorphous alloy are more compact and less defective, as well as higher chemical stability than the single crystal counterpart since the growth mechanism of the passive films are different. (2) The effect of the amorphous structure is closely related to the formation of the passive films. The states and distribution of the alloying elements in the passive films were analysised using XPS. It revealed that in contrast with the single crystal Zr2Ni alloy, passive films of the amorphous alloy have a higher corrosion resistance since it contained more ZrO2 and less NiO content."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64533
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	王冬朋. 非晶态结构对锆镍金属玻璃点蚀行为影响的研究[D]. 北京. 中国科学院金属研究所,2012.