Understanding the effect of holding time on interfacial microstructure evolution and mechanical properties of Ti3AlC2/Zr-4 brazed joints

In this work, the brazing of Zircaloy-4 (Zr-4) to Ti3AlC2 ceramic was investigated using a Ti-13Zr-21Cu-9Ni (wt.%) amorphous alloy at 930 degrees C with a holding time of 5-60 min. The typical multilayer structure of the joint was carefully characterized as Ti3AlC2/ZrC/Zr [Ti](ss) + [Zr(Ti)](2) [Cu(Ni)]/Zr [Ti](ss)/Zr-4. Ti3AlC2 was decomposed into TiCx due to the de-intercalation of Al, and Zr-4 dissolved into the molten amorphous TiZrCuNi fillers to form a Zr-based alloy which reacted with TiCx to form a ZrC particle layer on the Ti3AlC2 side. The microstructures and mechanical properties of the brazed joint were significantly influenced by dwell time, and the underlying evolution mechanisms were addressed based on the considerations of mutual dissolution, diffusion, and reaction among Ti3AlC2, Zr-4, and molten amorphous alloys. With the extension of holding time, the amount of [Zr(Ti)](2) [Cu(Ni)] in the brazed joints decreased gradually, while the ZrC layer thickened with (Ti, Zr)(ss) formed around the ZrC particles. The maximum shear strength of the joint, with an average strength of 187 +/- 34 MPa, was achieved by brazing at 930 degrees C for 5 min. A detailed fracture analysis was conducted to determine the failure mechanism. This work provides a reference for brazing other MAX phase materials and alloys.