Different Connection Models of Icosahedral Structures in TiAl Alloy Caused by the Cooling Rates

Abstract

High‐quality TiAl alloy is used to fabricate aerospace equipment with excellent mechanical properties because of its interesting properties, including low density, high specific yield strength, and better corrosion resistance. However, the fabrication of high‐quality TiAl alloy is challenging because the connection mechanism between different types of clusters in TiAl alloy during the rapid cooling process is not clear. This study uses molecular dynamics (MD) simulation methods to study the connection models of icosahedral (ICO) structures and other defective ICO structures at different cooling rates. The ICO structures represent the short‐range ordered structure in the system. Moreover, the complex connections between the ICO and its defective structures constitute the basic structural features of TiAl metallic glass. The results show that the connections between ICO and its defective structures differ significantly with the cooling rate. It is easier to form a more complex nanostructure connected by the ICO structures with higher proportion of Al central atoms at the lower cooling rate. As the temperature drops at the same rate, the number of Al central atoms with smaller atomic radius in the icosahedrons increases gradually, giving them an absolute advantage.