Mechanical response of reaction phases of the TiAl/steel brazed joint under a tensile load

This article offers a study of a mechanical response of the TiAl/Steel brazed joint. The (i) intermetallic reaction layer’s phases, (ii) the residue filler, and the (iii) base metals constitute the complex structure considered. The study features TiAl and 42CrMo steel brazed with an AgCuTi filler metal. The analysis includes the microstructural study and an evaluation of mechanical properties of the brazed joint. In addition, the fracture behavior of the joint under a tensile loading in situ is studied in the context of the impact that reaction phases may have on the joint properties. The results of the study indicate that the complex joint structure is due to the presence of a ternary intermetallic reaction layer, as well as the presence of intermetallics in the filler residue. The multilayered structure includes Ti₃Al+AlCuTi+AlCu₂Ti ternary intermetallic reaction layer, Ag(Cu) residue filler, AlCu₂Ti intermetallic dispersed in the residue braze and TiC layer. The hardness sequence of the structure has been established. The crack initiation, its propagation, and an ultimate fracture are associated primarily with Ti₃Al+AlCuTi+AlCu₂Ti ternary intermetalics layer.