Atomistic modelling of the γ-TiAl/α2-Ti3Al interfacial properties affected by solutes

Interfacial properties of gamma-TiAl/alpha(2)-Ti3Al binary-phase are very important to further understand and design new coating material based on TiAl alloys. In this work, a first-principles methodology has been used to analyze the impact of dilute solutes, including Cr, Nb, Cu, Zn, Si, Mo, and Re that segregated at the interface. It has predicted that the Ti is the preferential site for alloying these elements at the interface layer of gamma-TiAl and alpha(2)-Ti3Al. Cr, Nb and Mo increase slightly the interface energy leading to decrease stability of gamma-TiAl/alpha(2)-Ti3Al interface. While Cu, Zn and Si stabilize the phase interfaces. On the other hand, Re atoms have an opposite trend that could stabilize the gamma-TiAl/alpha(2)-Ti3Al interface when partitioned to gamma-TiAl layer and destabilize the gamma-TiAl/alpha(2)-Ti3Al interface when in alpha(2)-Ti3Al layer. The order of cleavage energy from low to high is Re < Mo < Si < Zn < Cu < Nb < Cr, suggesting thus Re is beneficial for ductility of titanium aluminides in term of lamellar structure when partitioned to alpha(2)-Ti3Al. Furtheremore, the electronic structure confirms that the TiAl/Ti3Al-Re interface is more ductile.