Journal of Welding Science

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.