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Ti600和Ni-25%Si合金钎焊接头性能及失效机理分析

Analysis of properties and failure mechanism of Ti600/Ni-25% Si joint

  • 摘要: 采用Ti-Zr-Ni-Cu非晶钎料对高温钛合金Ti600和Ni-25%Si (原子分数,%)合金进行钎焊试验,重点研究了钎焊温度对镍硅与钛合金接头组织及性能的影响,结合接头组织特征及断口结构分析阐明了Ti600和Ni-25%Si合金钎焊接头的失效机理. 结果表明,钎缝内部包含多个区域,随着连接温度从900 ℃上升至980 ℃,包含(Ti,Zr)2Si和Ti2Ni相的区域逐渐消失,包含Ti5Si3和Ti2Ni相的区域逐渐变厚,最终占据全部钎缝. 力学性能分析表明,随着钎焊温度的升高,接头抗剪强度先增大后降低. 当钎焊温度为960 ℃时,接头的抗剪强度能够达到峰值177 MPa. 在脆性Ti2Ni相基体上弥散分布的Ti5Si3相颗粒破坏了Ti2Ni相的连续性,阻碍了裂纹在钎缝内部的扩展是钎焊接头抗剪强度提升的根本原因.

     

    Abstract: Brazing of Ti600 to Ni-25%Si alloy was performed using Ti-Zr-Ni-Cu amorphous filler foil. The influence of brazing temperature on the microstructures and mechanical property of brazed joints have been studied and the strengthening mechanism of the Ti600/Ni-25%Si brazed joint was clarified. The results show that the brazing seam contains multiple reaction zones. With the increase of brazing temperature, the zone III comprised by (Ti,Zr)2Si and Ti2Ni disappears gradually while the zone IV with Ti5Si3 dispersing in Ti2Ni gradually occupies the brazing seam. As the brazing temperature increases, the shear strength of brazed joints first augmented, reached the peak value of 177 MPa at 960 ℃ and then decreased. The dispersing Ti5Si3 phase distributing in the brittle Ti2Ni phase, which hinders the crack propagation and strengthens the brittle Ti2Ni, improves the shear strength of the brazed joint obtained at elevated temperature.

     

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