Zn-Al-Li系和Zn-Al系钎料对SiC_p/ZL101铝基复合材料的润湿性

Wettability of Zn-Al-Li and Zn-Al system brazes on aluminum matrix composite of SiC_p/ZL101

为表征降熔元素Zn在铝基复合材料钎焊中的扩散行为及其对去膜效果的影响,并改善Zn基钎料的润湿性（添加活性元素Li）,用坐滴法在520℃、10-30 min、5 L/min流动Ar保护条件下测试纯Zn、Zn-5Al二元共晶、自制Zn-6Al-1Li三元共晶、自制Zn-21Al-3Li三元包共晶共4种钎料对SiCp/ZL101铝基复合材料的润湿性。结果表明：对于无Li的Zn基钎料,随保温时间的延长,Zn仅在局部范围可沿晶界扩散入Al基体,出现晶界液化甚至溶蚀,但难以出现晶粒液化,钎料/母材界面间隙依然难以消除;对于含Li活性钎料,Li的适度添加（约3%,质量分数）使得Zn的渗入在整个界面趋于均匀分布,消除了局部溶蚀与界面空隙,对润湿性有良好改善效果;Zn的渗入引起大量尺寸约为10μm的（Si）块在界面析出。

In order to characterize the diffusion behavior of Zn as melting point depressant （MPD） and its potential ability on removing oxide film during the brazing of aluminum matrix composite and improve the wettability of Zn based filler metals by adding active element of Li, the wettability of pure Zn, Zn-5Al eutectic, the developed Zn-6AI-ILi ternary eutectic and Zn-21Al-3Li ternary quasi-eutectic on the aluminum metal matrix composite of SiCp/ZL101 were tested with sessile drop method at 520℃ for 10-30 min within flowing argon （5 L/min） atmosphere. The results and that, for the Zn-base filler metal without lithium, with increasing the soaking time, the Zn atoms only penetrated into the matrix in local area only along the grain boundary, resulting in the dissolution of the grain boundary and even local erosion, but the grain dissolution can not occur, and the gap between the matrix and residual filler metal is obvious. For the active filler metal with lithium at a moderate level of about 3% （mass fraction）, Zn can uniformly diffuse into the matrix along grain boundary on the whole surface of the matrix covered by the filler, eliminating the local erosion and the interface gap, and hence improving the wettability on the composite. The diffusion of Zn into the matrix of ZL101 causes the precipitation of lots of silicon particles of about 10 μm along the interface.