Microstructure evolution and brazing mechanisms of the Ti₂AlC/Ni joints using nickel based filler alloy

The brazing of the Ti₂AlC ceramic to nickel has been successfully performed using nickel based filler alloy, to extend high temperature applications of Ti₂AlC ceramic. The interfacial morphology was observed by SEM, and the phases in the joint were characterized by EDS and XRD. During the brazing process, the diffusion of Ni from filler alloy to the Ti₂AlC substrate was discovered. Afterwards, the diffusion kinetics were studied by measuring the thickness of the ‘interaction zone’, and the activation energy was calculated to be 152 kJ/mol. In addition, the effect of brazing parameters on shear strength was studied. The results revealed that increasing thickness of the ‘interaction zone’ and ‘filler zone’ was favorable for relieving the thermal stress in the joint, led to an improvement in mechanical properties. Finally, the maximum shear strength of the Ti₂AlC/Ni brazed joints was measured to be 193 MPa, obtained at 1100 °C for 30 min.