Zn-Cu-Sn-Bi系锌基高温软钎料的组织与性能

Microstructure and properties of Zn-Cu-Sn-Bi high-temperature solders

关键词:  钎料  锌基钎料  性能  微观组织

Key words:  solder  Zn-based solder  properties  microstructure

摘要:

研制了一种熔化温度在350~500 ℃,钎焊铜和钢的Zn-2Cu-Sn-Bi系高温软钎料. 试验采用差示扫描量热法(DSC)对 Zn-2Cu-Sn-Bi系高温软钎料的熔化特性进行了研究. 结果表明,Zn-2Cu-Sn-Bi系高温软钎料固相线温度为382.39~391.80 ℃,液相线温度为391.97~401.50 ℃,凝固区间9.37~12.64 ℃. Zn-2Cu-Sn-Bi系高温软钎料钎焊铜平均润湿面积206 mm²,随Sn元素含量的增加,钎料的润湿性能增强,润湿角最小为5°. 微观组织观察发现,Zn-2Cu-Sn-Bi系高温软钎料组织由η-Zn相、ε-CuZn₅相、Bi相和β-Sn相组成. 钎焊接头产物为Zn-Cu化合物,界面反应层厚度80 μm,由贝壳状反应层ε-CuZn₄/CuZn₅,平直反应层β-CuZn和γ-Cu₅Zn₈组成.

Abstract:

In order to develop high temperature solders for brazing Cu and steel,a series of Zn-2Cu-Sn-Bi (wt-%) solders have been investigated. Through differential scanning calorimeter (DSC) analysis, the thermal properties of Zn-Sn-Cu-Bi solders were measured. The results showed that the solidus and liquidus temperatures of Zn-2Cu-Sn-Bi solders are 386.00-391.80 ℃ and 398.64-401.50 ℃, respectively, and the under-cooling temperatures are between 9.37 ℃ and 12.64 ℃. The wettability tests showed that the increase of Sn in Zn-2Cu-Sn-2Bi solders resulted in the increase of wetting area. The average wetting area was a of 206 mm², and the smallest contact angle was of 5°. The metallographic observations indicated that Zn-2Cu-Sn-Bi solder consisted of η-Zn matrix, dendrite β-Sn crystals, Bi phaseand ε-CuZn₅ intermetallic compounds. The Zn-Cu compounds were formed in the joints. The interfacial layer was about 80 μm thick, with one scallop-shaped ε-CuZn₄/CuZn₅ layer, and two flat layers β-CuZn and γ-Cu₅Zn₈.