金属间化合物Fe_2B在液态锌中的腐蚀机制  

Corrosion Mechanism of Intermetallic Compound Fe_2B in Liquid Zinc

作　　者：杜安[1] 马瑞娜[1] 温鸣[1] 范永哲[1] 曹晓明[1] 

机构地区：[1]河北工业大学材料科学与工程学院,天津300130

出　　处：《天津大学学报》2010年第7期633-638,共6页Journal of Tianjin University(Science and Technology)

基　　金：国家自然科学基金资助项目(50871037);河北省自然科学基金资助项目(E200600081)

摘　　要：利用扫描电镜、电子探针以及X射线研究了Fe2B的微观组织及被液态锌腐蚀后的界面形貌及化学组成,并运用固体与分子经验电子理论(EET)建立了Fe2B的价电子结构,对腐蚀过程中的反应扩散机制进行了合理的分析.结果表明:Fe2B在液态锌中的腐蚀机制以反应扩散为主;首先液态Zn原子扩散到Fe2B固体表面,然后沿能量较高的晶界进入Fe2B基体;Zn原子在Fe2B晶格中有限固溶,引起了Fe2B晶格畸变,同时在热应力作用下,Fe2B基体产生大量裂纹,液态锌沿着裂纹扩展方向渗入;当晶格畸变达到极限时,Fe原子周围的化学键全部断裂,Fe成为"自由"原子;"自由"的Fe原子与周围的Zn原子发生反应,生成Fe-Zn化合物;化合物从基体上剥落下来,漂移到液态锌中;Fe原子成为"自由"原子需要的能量越高,材料的耐腐蚀性能越好.The micro-structure of intermetallic compound Fe2B and its cross-section morphology and chemical com- position after corrosion in liquid zinc were investigated with scanning electron microscopy （SEM）, electron micro- probe analyzer and X-ray diffraction. The valence electron structure of Fe2B was studied based on empirical electron theory （EET）, and the mechanism of diffusion and reaction in the corrosion process was analyzed. Results show that the corrosion process of Fe2B alloy in liquid zinc is mainly composed by diffusion and reaction. Firstly the liquid zinc atoms diffused onto the surface of Fe2B and then entered solid matrix of Fe2B along the grain boundary with higher energy. With limited dissolution of Zn atoms in Fe2B lattice, which led to lattice distortion of Fe2B, and the effect of heat stress, many cracks appeared on the solid matrix of Fe2B and liquid zinc flowed into the matrix along the cracks. When solid dissolution of Zn atoms in Fe2B lattice was saturated, lattice distortion reached the limit and all bonds were broken around Fe atoms, which were then ＂free＂. After reaction of ＂free＂ Fe atoms with the sur- rounding Zn atoms, Fe-Zn compounds were produced, which then dropped from Fe2B matrix and moved into liquid zinc. The greater the energy needed for Fe atoms to become ＂free＂ atoms, the better the corrosion resistance per- formance of alloys.

关 键 词：腐蚀 Fe2B 金属间化合物 液态锌 键能 

分 类 号：TG174[金属学及工艺—金属表面处理]