The microstructural development and erosion mechanism of BaZrO3/Al2O3 double ceramics by Ti–46Al–8Nb alloy melt

In this study, the erosion of BaZrO 3 /Al 2 O 3 double ceramics by Ti-46Al-8Nb alloy melt was investigated at different melting temperatures (1833 K, 1873 K and 1913 K) and time (1800 s, 3600 s, 5400 s and 7200 s). The microstructure of erosion layer and the alloy ingot were analyzed as well as the oxygen content of the alloy ingot. The erosion mechanism was clarified in the kinetic perspectives. The results showed that the new oxide BaAl 2 O 4 production was attached on the ingot surface, and two kinds of inclusions, i.e ., (Ti, Zr) 5 (Si, Al) 3 and YAlO 3 , were formed in the ingot matrix. The thickness of erosion layer, the oxygen content of ingot, and the volume fraction of inclusions increased with increasing melting temperatures and time. In addition, these three phenomena were controlled by the kinetics of dissolution, and the time exponents were approximately equaled to 0.5, indicating that the erosion mechanism was dissolution controlled by mutual diffusion between the double ceramics and alloy melts. The activation energies of three phenomena were determined by Arrhenius equation, and three kinetic models were further established. • In this study, the erosion of BaZrO 3 /Al 2 O 3 double ceramics by Ti-46Al-8Nb alloy was investigated. The effects of the melted temperatures and time on the alloy-ceramic interaction, oxygen content and microstructure were studied. The erosion mechanism was analyzed from both thermodynamic and kinetic perspectives. The conclusions were obtained as follows: • A significant erosion occurred in the ceramic, resulting in the generation of BaAl 2 O 4 products. The erosion layer was attached on the surface of alloy ingot, and its thickness increased with increasing melted temperature and time. And the variation in thickness was controlled by the kinetics of dissolution, following to the Arrhenius equation: , indicating that the erosion mechanism was dissolution controlled by mutual diffusion between them. • The oxygen content in the alloy ingots was increased with the increasing melted temperature and time, and it was controlled by both thermodynamics and kinetics of dissolution. The derived Arrhenius equation: indicated that the dissolution of ceramic in the alloy melt was controlled by a long-range diffusion. • The alloy consisted of (γ-TiAl + α 2 -Ti 3 Al) with fully lamellae microstructure and a small amount of YAlO 3 and (Ti, Zr) 5 (Si, Al) 3 inclusions. The volume fraction of inclusions was increased with the melted temperature and time. It was controlled by the kinetics of dissolution, and conformed to the Arrhenius equation: . However, the volume fraction of inclusions was significantly low compared with the Y 2 O 3 crucible.