【作者】 罗群； 李谦； 张捷宇； 李麟； 周国治；

【Author】 Luo Qun;Li Qian;Zhang Jieyu;Li Lin;Zhou Guozhi;State Key Laboratory of Advanced Special Steels,Shanghai University;Institute of Genomic Material,Shanghai University;

【机构】 上海大学省部共建高品质特殊钢冶金与制备国家重点实验室； 上海大学材料基因工程研究院；

【摘要】 为了探究Ti添加导致热浸镀55wt.%Al-Zn-Si镀层锌花减小的机理,本文通过实验对比观察55wt.%Al-Zn-Si和55wt.%Al-Zn-Si-Ti镀层合金层的形貌和各物相的成分。为了减少杂质元素如V、Ce的影响和便于析出相的检测,本文利用高纯的原料锭配制了55wt.%Al-Zn-1.6Si-1Fe-0.7Ti合金,研究Fe和Ti过饱和后的析出相种类。SEM和EDS的结果表明,55wt.%Al-Zn-Si-Ti镀层中通常可以检测到颗粒尺寸大于10μm的金属间化合物,而55wt.%Al-Zn-Si镀层的金属间化合物颗粒尺寸小而均匀。配制的合金中,Fe和Ti过量将导致析出两种金属间化合物,分别为TiAl₃和Fe₄Al₁₃。利用Al-Zn-Si-Fe-Ti相图数据库计算610℃的55wt.%Al-Zn-1.6Si等温截面,结果显示过量Ti导致镀液中析出TiAl₃相,Fe含量超过饱和溶解度导致镀液中析出Fe₄Al₁₃相,计算得到的TiAl₃和Fe₄Al₁₃的成分与实验结果吻合。根据计算结果分析Ti添加导致锌花减小的机理为:Ti添加使镀液中析出TiAl₃相(Ti₂₅Al₆₀Si₁₅),消耗镀液中的部分Si,使镀液中有效Si含量降低,从而使Fe的饱和溶解度降低,析出更多的Fe₄Al₁₃。TiAl₃和Fe₄Al₁₃含量的增加使镀液中的形核密度增加,细化晶粒。更多还原

【Abstract】 In order to study the mechanism of reduction of spangle size for 55 wt.% Al-Zn-Si-Ti coating, the alloy layers of the hot-dip 55 wt.%Al-Zn-Si coatings and 55 wt.%Al-Zn-Si-Ti coatings were comparatively investigated by scanning electron microscopy（SEM） and energy dispersive X-ray spectrometer（EDS）. Aiming to avoid influence of the impurity elements（V and Ce） and easily identify the intermetallic compounds in the alloy, the high purity 55 wt.% Al-Zn-1.6Si-1Fe-0.7Ti alloy was prepared. The results showed that the size of Fe-Al-Si intermetallic compounds in 55 wt.% Al-Zn-Si-Ti coatingwas always larger than 10 μm. Many big intermetallic particles were observed at the center of the spangle, but the intermetallic particles in the 55 wt.% Al-Zn-Si coatings were small and distributed uniformly. The calculated isothermal sectionof 55 wt.% Al-Zn-1.6Si at 610 °C showed that the Ti addition made Ti Al₃ precipitated and the high Fe content led to the precipitation of Fe₄Al₁₃. The calculated compositions of Ti Al₃ and Fe₄Al₁₃ were consistent with that determined from experiment. The mechanism of grain reduction caused by Ti addition can by summarized as follows: the addition of Ti makes the Ti Al₃(Ti₂₅Al₆₀Si₁₅) formed, then the Si content would decrease in the bath, leading to the amount of precipitated Fe₄Al₁₃ increase. Both the Fe₄Al₁₃ and Ti Al₃ could act as the heterogeneous nucleation sites of the primary Al dendrites and refine the grains.更多还原