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<p>This study systematically investigates the dissimilar welding of intermetallic compound-based TiAl alloy and titanium alloy TC17 using linear friction welding (LFW), focusing on the microstructural characteristics and mechanical properties of the joints. Under optimized welding parameters, high-quality joints were achieved, exhibiting a tensile strength of 358&#xa0;MPa and a predominant brittle fracture mode localized at the TC17/TiAl interface. Microstructural analysis identifies three distinct regions: the base metal (BM), the thermo-mechanically affected zone (TMAZ), and the weld zone (WZ). The WZ is characterized by fine equiaxed grains formed through dynamic recrystallization, while the TMAZ exhibits elongated, deformed grains. A well-defined diffusion layer (10–20&#xa0;μm) is observed at the interface, with a microstructural transition sequence of TC17 (basketweave structure) → equiaxed <i>β</i> → <i>α</i>₂ → <i>γ</i> → TiAl (<i>γ</i> + <i>α</i><sub>2</sub>). The central <i>α</i><sub>2</sub> layer, measuring less than 5&#xa0;μm, is identified as the critical factor influencing joint mechanical behavior. Hardness profiling reveals a peak hardness exceeding 500&#xa0;HV at the weld center, primarily attributed to the <i>α</i><sub>2</sub> layer. Additionally, the edge region of the joint is prone to three types of microscopic defects—parallel cracks, vertical cracks, and interface voids—which can serve as potential fracture initiation sites, compromising joint integrity.</p>

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Microstructure and mechanical properties of linear friction welded dissimilar γ-TiAl/TC17 joints

  • 期刊论文

  • 发表日期：

    2025年10月31日

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  • Da Zhang,
  • Hanmo Cao,
  • Jiangtao Xiong,
  • Xin Wang,
  • Jinglong Li,
  • Wei Guo

摘要

This study systematically investigates the dissimilar welding of intermetallic compound-based TiAl alloy and titanium alloy TC17 using linear friction welding (LFW), focusing on the microstructural characteristics and mechanical properties of the joints. Under optimized welding parameters, high-quality joints were achieved, exhibiting a tensile strength of 358 MPa and a predominant brittle fracture mode localized at the TC17/TiAl interface. Microstructural analysis identifies three distinct regions: the base metal (BM), the thermo-mechanically affected zone (TMAZ), and the weld zone (WZ). The WZ is characterized by fine equiaxed grains formed through dynamic recrystallization, while the TMAZ exhibits elongated, deformed grains. A well-defined diffusion layer (10–20 μm) is observed at the interface, with a microstructural transition sequence of TC17 (basketweave structure) → equiaxed β → α₂ → γ → TiAl (γ + α2). The central α2 layer, measuring less than 5 μm, is identified as the critical factor influencing joint mechanical behavior. Hardness profiling reveals a peak hardness exceeding 500 HV at the weld center, primarily attributed to the α2 layer. Additionally, the edge region of the joint is prone to three types of microscopic defects—parallel cracks, vertical cracks, and interface voids—which can serve as potential fracture initiation sites, compromising joint integrity.