Characterizing the decomposition of Ti₂AlC during its brazing with Cu by using Ag-Cu filler alloy

The reaction process between Ti₂AlC and Ag-Cu filler alloy was mentioned in our previous study. However, the reaction mechanism between Ti₂AlC and filler alloy remained uncertain due to the existence of TiAl₂, which was widely distributed in the dual-phase Ti₂AlC substrate and exhibited intense reaction with Cu. In current research, pure-phase Ti₂AlC was brazed to Cu using Ag-Cu filler alloy respectively at 850°C and 900°C for 10 min. First of all, to investigate the influence of TiAl₂ on clarifying the reaction mechanism, Ti₂AlC substrates with different component (single phase and dual phase) were joined to Cu at 850°C for comparison. However, in these joints, it was difficult to find any other reactant except for AlCu₂Ti. Thus, the pure-phase Ti2AlC was brazed to Cu at 900°C, aiming to intensify the interaction between substrates and filler alloy. For characterizing the microstructure evolution in the joint, the typical region of the joint that contained all the reactants was selected and sliced by focused ion beam technology. Combining with transmission electron microscopy, all the decomposition products (e.g. Ti₃AlC₂ and TiC) in the joint were identified. Then the decomposition mechanism of Ti₂AlC was clearly disclosed.