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Ni含量对304/Sn-8Sb-4Cu-xNi/304钎焊接头组织与剪切性能的影响

Effect of Ni content on microstructure and shearing property of 304/Sn-8Sb-4Cu-xNi/304 solder joints

  • 摘要: 研究了Ni含量对Sn-8Sb-4Cu-xNi(x = 0, 0.5, 1和2,质量分数)钎料熔点和微观组织的影响,用Sn-8Sb-4Cu-xNi钎料对304不锈钢进行钎焊连接,分析了接头的界面组织与剪切性能. 结果表明,添加不同含量的Ni后,Sn-8Sb-4Cu-xNi均为近共晶钎料,其熔点约为245 ℃;Sn-8Sb-4Cu钎料组织由α相基体、Sb2Sn3 + Cu6Sn5 + Sn复合相和Cu6(Sn,Sb)5 相组成. 添加Ni元素后,钎料中块状Cu6(Sn,Sb)5转变为细小、均匀分布的 (Cu,Ni)6(Sn,Sb)5. 当Ni含量小于1%时,随Ni含量的增加,钎料中的复合相和(Cu,Ni)6(Sn,Sb)5相均增加;当Ni含量为2%时,钎料中的复合相和(Cu,Ni)6(Sn,Sb)5相均减少,但(Cu,Ni)6(Sn,Sb)5相中Ni含量增加至与Cu相当;Sn-8Sb-4Cu-xNi/304钎焊界面均形成了一层厚度约1.5 μm的扩散反应层,EDS分析显示,该层为FeSn2化合物. 钎缝中全部为Cu6Sn5型化合物,未见Sn-Sb 型化合物. Ni元素的添加,提高了304/Sn-8Sb-4Cu-xNi/304钎焊接头的抗剪强度,当Ni含量为0.5%时,接头抗剪强度最大,为67 MPa,与不含Ni钎料相比提高了60%. 所有接头的断裂位置均位于钎缝.

     

    Abstract: Effect of Ni content on melting point and microstructure of Sn-8Sb-4Cu-xNi (x=0, 0.5, 1 and 2, mass fraction) solders were investigated. 304 stainless steel were joined by Sn-8Sb-4Cu-xNi solders, and interfacial microstructure and shearing property of the solder joints were analyzed. The results showed that all of the Sn-8Sb-4Cu-xNi with different Ni content are near eutectic solders, with a melting point of 245 ℃. The microstructure of Sn-8Sb-4Cu solder was consisted of α phase, Sb2Sn3 + Cu6Sn5+Sn composite phase and Cu6(Sn,Sb)5 phase. After the addition of Ni, the bulk Cu6(Sn,Sb)5 transformed into fine and uniformly distributed (Cu,Ni)6(Sn,Sb)5. When Ni content was less than 1%, the amount of composite phase and (Cu,Ni)6(Sn,Sb)5 phase increased with the increasing of Ni content. When Ni content increased to 2%, the amount of composite phase and (Cu,Ni)6(Sn,Sb)5 phase decreased with the increasing of Ni content, however, Ni content in the (Cu,Ni)6(Sn,Sb)5 phase increases to be comparable to Cu. A diffusion layer with a thickness of about 1.5 μm formed at the Sn-8Sb-4Cu-xNi/304 interface, which was identified to be Fe2Sn by EDS. Only Cu6Sn5 type intermetallic compounds formed in the solders of 304/Sn-8Sb-4Cu-xNi/304 joints. The addition of Ni element improved the shear strength of 304/Sn-8Sb-4Cu-xNi/304 brazed joints, and the maximum shear strength of 67 MPa was achieved when the Ni content was 0.5%, which was 60% higher compared to the Ni-free brazing material. The shear fracture locations of all joints were located in the soldering seam.

     

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