Abstract: The energetics,geometrical structure and elastic constant of L10-TiAl intermetallic compound alloyed by 3d transition metal(TM) elements are investigated with the first-principle method based on plane-wave pseudopotential theory.The site preference of TM elements in Ti7Al8X and Ti8Al7X (X=3d transition metal) supercell model are calculated by the comparison between formation energy of Ti7Al8X and Ti8Al7X supercell.The results show that TM elements,such as Sc,V and Cr mainly substitute for the Ti site in L10-TiAl;the others,e.g.Mn,Fe,Co,Ni,Cu and Zn primarily substitute for the Al site in L10-TiAl.The equilibrium lattice constant K(K=|c/a-1|) value of Ti7(8)Al8(7)X supercell shows that the addition of Mn,Fe and Co TM elements individually is favorable to the improvement of the room temperature brittleness of L10-TiAl intermetallic compound,while other 3d TM elements addition is not helpful.The ratio value G/B of Ti7(8)Al8(7)X supercell shows that the addition of V,Mn,Co and Ni TM elemen...更多ts individually is favorable to the improvement of the room temperature brittleness of L10-TiAl intermetallic compound.The inconsistency between above theory research and the existing experiment results is possible to concentration of alloying atom.还原