Microstructural Evolution of TLP Bonded Ti3Al-Nb Alloy Joints

In the present study microstructural evolution in transient liquid phase (TLP) bonded Ti Al-Nb alloy joints using a pure copper as interlayer was investigated. TLP bonded Ti Al-Nb alloy joints composed of intermetallic compound layers were produced. Microstructural evolution of joints depended on both bonding time and bonding temperature. With increasing bonding time and bonding temperature, the joint width increased and amount of compounds in the joint decreased. The joint microstructure at 1173 K × 1 min mainly consisted of Ti (solid solution) + Ti Cu + TiCu + Ti Cu + Ti Cu + TiCu + Cu (solid solution) phase and it changed to Ti (solid solution) + Ti Cu + TiCu at 1223 K × 60 min. Compounds formed on cooling from the bonding temperature by liquid phase were eliminated from the joint at 1223 K × 60 min due to isothermal solidification of liquid phase. The increase of the width of joint is attributed to the composition difference between the isothermal solidification production and its adjacent base material.