Microstructural evolution and bonding mechanisms of the brazed Ti/ZrO2 joint using an Ag68.8Cu26.7Ti4.5 interlayer at 900 degrees C

Abstract

In this study, 3 mol% Y2O3-stabilized zirconia (3Y-ZrO2) and commercially pure titanium (cp-Ti) joints were fabricated with an Ag68.8Cu26.7Ti4.5 interlayer (Ticusil) at 900 degrees C for various brazing periods. After brazing at 900 degrees C/0.1 h, Ti2Cu, TiCu, Ti3Cu4, and TiCu4 layers were present at the Ti/Ticusil interface, while TiCu and TiO layers were observed at the Ticusil/3Y-ZrO2 interface. In the residual interlayer, clumpy TiCu4 was formed along with the Ag solid phase. After brazing at 900 degrees C/1 h, Ti3Cu3O and Ti2O layers were formed at the interlayer/ZrO2 interface, while Cu2O was precipitated in the residual interlayer with [111](Cu2O)//[111](Ag) and (20 (2) over bar)(Cu2O)//(20 (2) over bar)(Ag). After brazing at 900 degrees C/6 h, a two-phase (alpha-Ti + Ti2Cu) region was observed on the Ti side with [2 (1) over bar(1) over bar0](alpha-Ti)//[100](Ti2Cu) and (0002)(alpha-Ti)//(0 (1) over bar3)(Ti2Cu), while the TiCu layer grew at the expense of Ti3Cu4 and TiCu4. The bonding mechanisms and diffusion paths were explored with the aid of Ag-Cu-Ti and Ti-Cu-O ternary phase diagrams.