Journal of Welding Science

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The aim of this study is investigation of TLP variables on microstructure and mechanical properties of Al2024 to Ti-6Al-4V bonding for TLP joint. For this purpose, the sheets were prepared with dimension of 130×32×3 mm from Ti-6Al-4V and Al2024 alloys and 50µm thick Sn-5.3Ag-4.2Bi foil as interlayer. Sn-5.3Ag-4.2Bi foil prepared with dimension of 32×25 mm. Two alloys was joint together by process of Successive stage Transient Liquid Phase (S-TLP). This process is contains two stages. The first one is Transient Liquid Phase (TLP) of Ti-6Al-4V and the second stage is diffusion bonding of Al2024 to Ti-6Al-4V. In the first stage, TLP process was used for joining of Ti-6Al-4V to Ti-6Al-4V samples. This process carried out under argon gas at 2 atmosphere and at 620 °C. After the end of first stage, the samples were broken from the joint region and then, the obtained surface was jointed to Al2024 with new interlayer. In the second stage, that is soldering, the samples were placed in furnace under argon gas at 2 atmosphere and at 453 °C. Maximum tensile strength of diffusion bonding was  about 62 Mpa.

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This research focuses on the dissimilar joining of Ti6Al4V and Inconel 718 alloys using the Transient Liquid Phase (TLP) bonding process with a BNi2 foil and a copper interlayer. The objective is to analyze the effects of temperature (850, 950, and 1050 °C) and holding time (10, 20, and 30 minutes) on the microstructure, phase composition, and mechanical properties of the bonding region. DSC analysis indicated that melting reactions begin around 950 °C, attributed to the formation of eutectic compounds in the Cu-Ni-B system. SEM and EDS examinations confirmed the formation of intermetallic phases such as Ti₂Ni, NiTi, Cr₂Ti, and ceramic phase Ni₃B in different regions of the joint. Under optimal conditions (950 °C for 20 minutes), a uniform microstructure, controlled boron diffusion, and formation of stable phases were observed. The hardness in the DAZ region was approximately 420–450 HV. In contrast, higher temperatures and extended holding times led to the formation of brittle phases, solidification cracks, and interfacial discontinuities. The diffusion coefficient of titanium under optimal bonding conditions was estimated to be 2.8×10⁻¹¹ m²/s. These findings emphasize the importance of precise control over process parameters to achieve high-quality joints and prevent structural defects.