First-principles calculations of structural, mechanical and electronic properties of TiNi-X (X=C, Si, Ge, Sn, Pb) alloys

We adopted the first-principles calculations within density functional theory (DFT) to investigate the structures, elastic, and electronic properties of ternary TiNi-X alloys with different four main-group elements by using the CASTEP code. The lattice constants and volumes increase gradually from C to Pb. The mechanical stability has been discussed by utilizing the criteria. All alloys are mechanically stable except TiNiPb. The values of Young's modulus gradually decreased. Oppositely, the values of B/G and ν are increased, respectively. The ductility/brittleness of alloys is distinct. In addition, the width of pseudogap is gradually decreased, which is consistent with hardness, showing that the covanlency of TiNi-X alloys is decreased. Similarly, these properties of the remaining alloys are also discussed and results are stated in the paper.