AbstractCu/Al composite structures have considerable prospect for applications in refrigeration, automotive, power plant, and aerospace industries. The corrosion resistance of the Cu/Al joints is crucial to these applications. In this paper, corrosion behaviors of the Cu/Al joints brazed with three kinds of commercial Zn-Al filler metals were evaluated by salt spray test. The microstructure and composition of the brazing seam before and after corrosion were investigated and compared. The results showed that there were two kinds of corrosions in the joints, i.e., pitting corrosion at exposed brazing seam and corrosion cracks inside brazing seam. The pitting corrosion occurred at the massive Zn-rich precipitates and can be impeded by staggered CuAl2 phases. The corrosion cracks propagated along the diffusion layer or Zn-rich precipitates. Thick diffusion layer and massive Zn-rich precipitates accelerated the propagation of the corrosion crack. The joint brazed with Zn-15Al, Zn-22Al, and Zn-28Al lost 45%, 38%, and 30% the initial strength after 36 h salt spray corrosion, respectively. In general, the increase of Zn content in the filler metals resulted in drastic decline of the joint corrosion resistance.

中文翻译：

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Zn-Al合金钎焊Al / Cu异种接头钎焊缝中的腐蚀行为

摘要Cu / Al复合结构在制冷，汽车，发电厂和航空航天工业中具有广阔的应用前景。Cu / Al接头的耐腐蚀性对于这些应用至关重要。通过盐雾试验评价了三种钎料Zn / Al钎料钎焊Cu / Al接头的腐蚀行为。研究并比较了腐蚀前后钎焊缝的组织和组成。结果表明，接头处存在两种腐蚀，即裸露的焊缝点蚀和焊缝内部的腐蚀裂纹。点状腐蚀发生在大量富锌沉淀物上，并且可以被交错的CuAl2相阻止。腐蚀裂纹沿着扩散层传播或富锌沉淀物。较厚的扩散层和大量富锌沉淀物加速了腐蚀裂纹的扩展。盐雾腐蚀36 h后，用Zn-15Al，Zn-22Al和Zn-28Al钎焊的接头的初始强度分别降低了45％，38％和30％。通常，填充金属中Zn含量的增加会导致接头抗腐蚀性的急剧下降。