FEM analysis of thermal/residual stresses in brazing TiB₂ cermet/TiAl joints

Finite element method was used to calculate residual stresses which were developed when TiAl was bonding to TiB₂ cermet by Ag-based filler metal during cooling from joining temperature. The stress distribution of the joint at different joining temperature was studied. The results show that the residual stress concentration caused by the thermal expansion mismatch between three layers was observed both in TiAl/filler metal interface and in TiB₂ cermet/filler metal interface. Especially, the maximum value of residual stresses between TiAl and filler metal are higher than that between TiB₂ cermet and filler metal. Stress distribution is slightly dependent on joining temperature. But when the joining temperature becomes lower, the value of residual stress at the same position decreases accordingly.