铝基钎料真空钎焊接头的腐蚀性

采用NaCl的质量分数为3．5％的溶液对四种Al-Si-Cu钎料的真空钎焊接头进行全浸试验，对腐蚀后的钎焊接头进行观察，分析接头的腐蚀类型，研究接头的腐蚀机理，对Cu的晶界偏析及扩散进行了讨论。结果表明，铝基钎料真空钎焊后的接头仍然存在腐蚀问题，腐蚀产物为A1Cl3、Al(OH)3、Al(OH)2Cl，腐蚀类型有点蚀和晶间腐蚀；并且随着Cu含量的增加腐蚀加重，Cu的偏析与扩散对接头腐蚀行为产生重要的影响，在晶界形成他Cu，使晶界周围形成贫Cu区，与晶粒内部处于钝态的αAl存在较大电位差，构成局部腐蚀电池，形成晶间腐蚀。

Corrosion of brazed joints with aluminum-based filler metals in vacuum

Four kinds of brazed joints brazing with Al-Si-Cu filler metals in vacuum were corroded in 3.5 pct NaCl solution.The microstructures,corrosion patterns,as well as the segregation and diffusion of Cu element in the grain boundary of the as-corroded joints were investigated,and a corrosion mechanism was proposed.The results showed that corrosions such as pitting and intergranular corrosion still existed in the brazed joints,and the corrosion contaminants were AlCl 3,Al(OH) 3 and Al(OH) 2Cl.As Cu content in the Al-Si-Cu filler metals increased,the corrosion of the joints became more serious.It was found that the segregation and diffusion of Cu element significantly affected the corrosion characte-ristics.A poor Cu element area was observed nearby grain boundary,and Al 2Cu phase was found on the grain boundary.Because of the potential difference between the grain and grain boundary,a local corrosion cell was formed and resulted in the intergranular corrosion of the joint.