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<p>Ti/Al heterogeneous structures exhibit significant potential in high-end equipment applications, particularly aerospace engineering, owing to their lightweight nature and high specific strength. However, the reliability of conventional welding techniques is severely constrained by issues such as excessive growth of brittle intermetallic compounds (IMCs) at the interface and localized thermal stress concentrations. This study innovatively employs Wire Arc Additive Manufacturing (WAAM) technology, leveraging its advantages of controlled heat input, low dilution rate, and near-net-shape capability, to achieve direct fabrication of Ti/Al structures. The governing mechanisms of Cold Metal Transfer (CMT), Direct Current Pulse (DC-P), and their hybrid mode (CMT + P) on the interfacial microstructure and properties of the heterogeneous joint were systematically investigated. Results indicated that heat input predominantly governed interfacial morphology and elemental diffusion. The CMT mode, characterized by the lowest heat input, produced the thinnest interfacial layer (6.5 ± 0.8&#xa0;μm). Conversely, the DC-P mode, with higher heat input, resulted in a significantly thickened interface (11.2 ± 1.5&#xa0;μm), while CMT + P demonstrated an intermediate interfacial thickness (8.5 ± 0.6&#xa0;μm). Elemental analysis confirmed Ti-dominated diffusion toward the Al side, leading to the formation of Ti<sub>3</sub>Al and TiAl<sub>3</sub> intermetallic compounds within the reaction layer. TiAl<sub>3</sub> grains exhibited directional growth along the deposition direction, developing a pronounced {001} texture. Mechanical testing revealed that all specimens underwent quasi-cleavage fracture due to the presence of brittle phases. Notably, the CMT + P joints achieved the highest tensile strength (117 ± 12&#xa0;MPa), surpassing those of CMT (85 ± 8&#xa0;MPa) and DC-P (73 ± 23&#xa0;MPa) joints. This enhancement is attributed to pulse modulation in CMT + P, which refines IMC grains and optimizes interfacial bonding behavior. This work deepens the mechanistic understanding of interface regulation, thereby offering novel pathways to overcome limitations of traditional joining methods and advancing lightweight manufacturing for high-value industrial applications.</p>

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The Influence of WAAM Mode on the Interfacial Microstructure and Mechanical Properties of Ti/Al Heterogeneous Structure

  • 期刊论文

  • 发表日期：

    2026年4月21日

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  • Guan Jieren,
  • Liu Yunhua,
  • Wang Qiuping,
  • Wang Rui,
  • Liu Kun

摘要

Ti/Al heterogeneous structures exhibit significant potential in high-end equipment applications, particularly aerospace engineering, owing to their lightweight nature and high specific strength. However, the reliability of conventional welding techniques is severely constrained by issues such as excessive growth of brittle intermetallic compounds (IMCs) at the interface and localized thermal stress concentrations. This study innovatively employs Wire Arc Additive Manufacturing (WAAM) technology, leveraging its advantages of controlled heat input, low dilution rate, and near-net-shape capability, to achieve direct fabrication of Ti/Al structures. The governing mechanisms of Cold Metal Transfer (CMT), Direct Current Pulse (DC-P), and their hybrid mode (CMT + P) on the interfacial microstructure and properties of the heterogeneous joint were systematically investigated. Results indicated that heat input predominantly governed interfacial morphology and elemental diffusion. The CMT mode, characterized by the lowest heat input, produced the thinnest interfacial layer (6.5 ± 0.8 μm). Conversely, the DC-P mode, with higher heat input, resulted in a significantly thickened interface (11.2 ± 1.5 μm), while CMT + P demonstrated an intermediate interfacial thickness (8.5 ± 0.6 μm). Elemental analysis confirmed Ti-dominated diffusion toward the Al side, leading to the formation of Ti3Al and TiAl3 intermetallic compounds within the reaction layer. TiAl3 grains exhibited directional growth along the deposition direction, developing a pronounced {001} texture. Mechanical testing revealed that all specimens underwent quasi-cleavage fracture due to the presence of brittle phases. Notably, the CMT + P joints achieved the highest tensile strength (117 ± 12 MPa), surpassing those of CMT (85 ± 8 MPa) and DC-P (73 ± 23 MPa) joints. This enhancement is attributed to pulse modulation in CMT + P, which refines IMC grains and optimizes interfacial bonding behavior. This work deepens the mechanistic understanding of interface regulation, thereby offering novel pathways to overcome limitations of traditional joining methods and advancing lightweight manufacturing for high-value industrial applications.