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<p>The repair of cracks in aeroengine turbine vanes using wide-gap brazing, particularly through isothermal solidification via melting-point depressant (MPD) element diffusion, is indeed susceptible to pore formation, which can significantly degrade the high-temperature mechanical performance of the brazing joint. In this study, wide-gap brazed joints were prepared using two methods, namely atmosphere protection and vacuum hot-pressing. Based on the mixing ratios of BNi-2 brazing filler metal and Hastelloy X powders, the evolution of pore defects in the brazed joints and the underlying pore formation mechanism are elucidated. The results demonstrate that when the BNi-2 brazing filler metal is present in a large quantity in a brazing joint prepared under an Ar atmosphere protection, large-scale and nearly spherical pores are formed easily. A transition from spherical to irregular pore shapes occurs with an increase in the alloy powder content, and when the BNi-2 brazing filler metal and alloy powder contents are similar, the porosity reaches its peak. The implementation of the vacuum hot-pressing process effectively eliminates pore defects, with the minimal occurrence of such defects when the BNi-2 brazing filler metal and alloy powder contents are similar. Considering the vacuum hot-pressing process, when the BNi-2 brazing filler metal or the alloy powder is the predominant component in the joint, the joint tends to exhibit brittle fracture, while an approximately balanced proportion of BNi-2 brazing filler metal to alloy powder results in predominantly ductile fracture behavior.</p>

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Research on the formation mechanism of pore defect and mechanical properties of wide-gap brazing joints

  • 期刊论文

  • 发表日期：

    2026年1月6日

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  • Yubo Sun,
  • Weiyi Zhao,
  • Yimeng Du,
  • Chaoqun Ma,
  • Suteng Zhan,
  • Kunying Ding

摘要

The repair of cracks in aeroengine turbine vanes using wide-gap brazing, particularly through isothermal solidification via melting-point depressant (MPD) element diffusion, is indeed susceptible to pore formation, which can significantly degrade the high-temperature mechanical performance of the brazing joint. In this study, wide-gap brazed joints were prepared using two methods, namely atmosphere protection and vacuum hot-pressing. Based on the mixing ratios of BNi-2 brazing filler metal and Hastelloy X powders, the evolution of pore defects in the brazed joints and the underlying pore formation mechanism are elucidated. The results demonstrate that when the BNi-2 brazing filler metal is present in a large quantity in a brazing joint prepared under an Ar atmosphere protection, large-scale and nearly spherical pores are formed easily. A transition from spherical to irregular pore shapes occurs with an increase in the alloy powder content, and when the BNi-2 brazing filler metal and alloy powder contents are similar, the porosity reaches its peak. The implementation of the vacuum hot-pressing process effectively eliminates pore defects, with the minimal occurrence of such defects when the BNi-2 brazing filler metal and alloy powder contents are similar. Considering the vacuum hot-pressing process, when the BNi-2 brazing filler metal or the alloy powder is the predominant component in the joint, the joint tends to exhibit brittle fracture, while an approximately balanced proportion of BNi-2 brazing filler metal to alloy powder results in predominantly ductile fracture behavior.