Homogenization treatment-induced reduction of brittle intermetallic compounds in Ti₂AlNb/Ti60 brazed joints: Effect on microstructure and mechanical properties

The microstructure evolution and mechanical properties of Ti₂AlNb/Ti-36.5Zr–10Ni–15Cu-0.5Co-0.5Nb/Ti60 brazed joints before and after homogenization treatment were comprehensively evaluated. Initially, the joints brazed at 900 °C for 15 min exhibited a continuous coarse strip network of Ti₂Cu, Ti₂Ni, Zr₂Cu and Zr₂Ni brittle intermetallic compounds in the central region of the braze seam, which detrimentally affecting the mechanical properties. Subsequent homogenization at 600 °C for 1 h, the amount of continuous brittle intermetallic compounds significantly decreased through sufficient atomic diffusion. Concurrently, the inadequately transformed eutectic β-Ti within the intermetallic compounds underwent an active eutectoid reaction. This structural transformation established a coherent interface with elastic distortion between the α-Ti and intermetallic compounds, effectively minimizing the lattice mismatch. Thus, a widmanstatten structure (i.e., acicular intermetallic compounds within a eutectoid microstructure matrix) with improved mechanical properties was formed. Consequently, a mean shear strength of 350.3 MPa was attained after treatment at 600 °C for 1 h, marking a substantial 206 % increase compared to that before homogenization treatment. This finding underlines the pivotal role of homogenization treatment in optimizing the performance of aeroengine components.