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

Abstract

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 γ-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.

Molecular dynamics simulations on the connectivity of topologically close-packed clusters in TiAl3 alloys

“…We extended the connectivity to several TCP clusters and discovered a new representation that can be applied to arbitrary systems, whether single or complex. Owning to its comparatively high glass-forming capacity, the Ti-Al [15][16][17][18] alloy has attracted attention as an excellent material for engineering purposes, providing an occasion to investigate the structural development in the glass formation process [19][20][21][22]. In this study, we combined the proposed method and the average connectable TCP cluster coefficient (C A-TCP ) with TiAl 3 to demonstrate the connectivity of TCP central atoms of TiAl 3 and obtained the expected results.…”