Site preference of Zr in Ti3Al and phase stability of Ti2ZrAl

[摘要] The site preference of Zr atoms in Ti₃Al and the phase stability of Ti₂ZrAl are examined using first-principles electronic structure total energy calculations. Of the sixteen possible ways in which Ti, Zr and Al atoms can be arranged, in the lattice sites corresponding to $D0_{19}$ structure of Ti₃Al, to obtain Ti₂ZrAl, it is s hown that Zr atoms prefer to get substituted at the Ti sites. It is further shown that among the seven crystal structures considered, $D0_{19}$-like and $L1_2$-like are the competing ground-state structures of Ti₂ZrAl. The above results are in agreement with the experimental results reported in the literature. Calculated values of equilibrium lattice parameters, heat of formation and bulk modulus of Ti₂ZrAl are presented. The basis for the structural stability and bonding are analysed in terms of the density of states. Between the two possible 𝐵2-like structures, Ti₂ZrAl shows enhanced stability for the one where Zr is substituted in the Ti sublattice, which again is in agreement with the experimental observation.

[学科分类] 材料工程

[关键词] Site preference;phase stability;first-principles calculations;Ti3Al.