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钎焊温度对316L/AuSi/NiTi接头界面组织与力学性能的影响

Effect of brazing temperature on interfacial microstructure and mechanical property of 316L/AuSi/NiTi joint

  • 摘要: 采用AuSi共晶钎料成功实现了316L不锈钢和NiTi形状记忆合金的连接. 使用扫描电子显微镜和能谱仪等分析测试手段对不同钎焊温度下获得的接头界面组织进行了分析. 结果表明,316L/AuSi/NiTi接头典型界面微观组织为316L/(Fe,Cr)5Si3/Au(s,s) + Ti14Ni49Si37( + Si)/Ni4Si7Ti4 + NiSiTi/NiTi. 随着钎焊温度的升高,316L不锈钢侧(Fe,Cr)5Si3层逐渐形成并变厚,NiTi合金侧的NiSiTi层先增厚后减薄,钎缝中的硅含量逐渐减少. 剪切试验表明,当钎焊温度为600 ℃、保温时间为30 min时,钎焊接头的抗剪强度最高为34 MPa. 接头的断裂路径分析表明,接头沿钎缝中的固溶体发生断裂.

     

    Abstract: The NiTi shape memory alloy was successfully brazed with 316L stainless steel by AuSi filler metal. The interfacial microstructures of brazed joints at different temperatures were analyzed by scanning electron microscope and energy dispersive spectrometer. The results showed that the typical interfacial microstructure of 316L/AuSi/NiTi joint was 316L/(Fe,Cr)5Si3/Au(s,s)+Ti14Ni49Si37(+Si)/Ni4Si7Ti4+NiSiTi/NiTi. With the rising of temperature, the (Fe,Cr)5Si3 layer on 316L stainless steel side was gradually formed and grew thicker, while the NiSiTi layer on NiTi alloy side was thick at first and then became thinner. Meanwhile, the content of Si in the braze seam decreased gradually. The shear test indicated that the brazed joint at 600 ℃ for 30 min exhibited the highest shear strength of 34 MPa. The path of fracture analysis showed that the joint tended to fracture along the solid solution in the brazing seam.

     

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