Computational Discovery of the Qualitative Electronegativity-Wettability Relationship in High-Temperature Ceramics-Supported TiAl Alloys

The inevitable interaction between high-temperature ceramics (HTCs) and molten TiAl alloys during the casting process tends to cause the increased oxygen concentration, fracture, and embrittlement within TiAl alloys, and the interaction is closely related to wettability. Herein, the underlying mechanism of wettability (i.e., contact angle) between HTCs and molten TiAl alloys is systematically investigated by molecular dynamics (MD) simulations. Taking the interaction between the common adopted crucible (i.e., BaZrO3, Y2O3, ZrO2, and Al2O3) and molten TiAl alloys, for example, the calculated contact angles between gamma-TiAl and HTCs decrease in the sequence of BaZrO3, Y2O3, ZrO2, and Al2O3 and with the Ti content of TiAl alloys increasing. This is in agreement with the experimental results, verifying the feasibility of MD simulations. In addition, based on MD simulations, the electronegativity of metal elements within HTCs decreases in the order of Al2O3, ZrO2, Y2O3, and BaZrO3, which further discloses the relationship between electronegativity and wettability, i.e., smaller electronegativity of metal elements leads to worse wettability of HTCs. This might push forward the design of HTCs with better stability, such as BaZrO3 doped by Hf, Y, lanthanide, or actinide elements and BaHfO3.

Automated summary

The wettability mechanism between high-temperature ceramics (HTCs) and molten TiAl alloys is systematically investigated by molecular dynamics simulations. The results reveal that wettability is related to the electronegativity of metal elements and the Ti content of TiAl alloys.