Residual stress induced failure of Ti-6Al-4V/Si3N4 joints brazed with Ag-Cu-Ti filler: The effects of brazing zone’s elasto-plasticity and ceramics' intrinsic properties

The residual-stress induced failure of Ti-6Al-4V/Si3N4 joints brazed with two different Si3N4 ceramics possessing intrinsic properties was elucidated through experimental and finite-element (FE) thermo-mechanical simulations incorporating the local elasto-plastic as-received Ag-Cu-Ti filler brazing zone characterized by nano-indentation. All tested fractured mainly from due to residual stress, their bending strengths increased when using higher strength. FE-analysis based on filler’s overestimated nominal approximately 100 MPa in both joints; nano-indentation revealed that depletion ductile Ag-Cu phase growth hard Cu-Ti intermetallic compounds reduced plastically deformable thickness after being brazed, whereby they resulted stress ceramics. Finally, validity FE-estimated enhanced considering effective (30 μm) instead state (50 μm).