Ab initio pseudopotential calculations an the effect of Mn doped on lattice parameters of Ll(0) TiAl

Effects of ternary alloying with Mn on the electronic structure and lattice geometry of TiAl compounds are studied using ab initio pseudopotential met hod combined with the technique of atomic relaxation. The calculation are p reformed on three supercells with different percentage content of Mn. Fine k-point mesh and cutoff energy are chosen to ensure the precision and numer ical convergence. Our results show that the effect of Mn atom on lattice pa rameters of TiAl is strong and nonuniform. The dopant of Mn can cause latti ce contraction of TiAl along its c-axes. As a result, the lattice tetragona lity of TiAl, which is known to relate with the intrinsic brittleness, can be reduced. The electronic structure of supercells illustrates that such a contraction is primarily contributed by the strong charge accumulation alon g the first nearest neighbors in the Ti-Mn directions. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.