Brazing Zircaloy-4 to Ti3AlC2 using Ti–Zr–Cu–Ni amorphous alloys: Microstructural evolution and mechanical properties

Abstract

Brazing of Zircaloy-4 (Zr-4) to Ti3AlC2 ceramic was investigated using a Ti–13Zr–21Cu–9Ni (wt.%) amorphous braze alloy (ABA) at temperatures ranging from 840 °C to 990 °C for 5 min. The interfacial reactions of the brazed joint were comprehensively analyzed, revealing a distinct multilayer structure consisting of Ti3AlC2/ZrC/α-Zr(Ti) + [Zr(Ti)]2Cu + [Zr(Ti)]2[Cu(Ni)]/α-Zr(Ti)/α-Zr. The formation of the ZrC carbide particle layer primarily results from the reaction between the molten ABA and decomposed Ti3AlC2 caused by the de-intercalation of Al. Additionally, the dissolution of Zr-4 into the ABA induces an alteration in the composition of the Zr-4/ABA interface, leading to the formation of α-Zr(Ti) isothermal solidification dendrites. The effect of brazing temperature on the mechanical properties of the joint was investigated and detailed fracture analysis was conducted to determine the failure mechanism. The fracture path result indicated that the joint primarily fractured within the ZrC layer due to the mismatch of hardness, rather than within the reticular [Zr(Ti)]2[Cu(Ni)] segregation phase. The maximum shear strength of the brazed Ti3AlC2/Zr-4 joint with an average strength of 187 ± 34 MPa was achieved by brazing at 930 °C for just 5 min. With the increase in brazing temperature, the thickness of the ZrC ceramic layer became thicker in an undulating manner, and the content of Zr-based alloy particles in the ZrC layer increased gradually, resulting in a slight decrease in the bearing capacity of the joint. The presented results provide valuable insights into the microstructural evolution, interfacial reactions, and mechanical properties of the Ti3AlC2/Zr-4 brazed joints using amorphous alloys.