Structural, mechanical, and thermodynamic properties of Ni–Ti intermetallic compounds: First-principle calculation

Intermetallic compounds were applied widely in the fields of automotive and aerospace because of its excellent shape memory effect. In this work, the structural, mechanical, and thermodynamic properties of Ni–Ti intermetallic compounds are studied by first-principle calculation. The results show that Ti, NiTi3, NiTi2, NiTi, Ni4Ti3, Ni3Ti, Ni4Ti, and Ni are stable based on Born stable criterion. On the mechanical aspect, the bulk modulus of Ni–Ti intermetallic compounds increases with the rising electron density. Their ductility is ranked as follows: NiTi3 > Ni4Ti3 > NiTi2 > Ni4Ti > NiTi > Ni3Ti. And when the ratio of Ni and Ti is 3:1, it is the hardest. In addition, the Ni–Ti intermetallic compounds in this work are anisotropy, except NiTi2. On the thermodynamic aspect, the Debye temperature θD, melting point Tm, and minimum thermal conductivity kmin of Ni–Ti intermetallic compounds increase first and then decrease with the rising content of Ni. The θD and kmin of NiTi3 are the minimum among the Ni–Ti ICs mentioned above, and θD of Ni3Ti and kmin of NiTi are both the maximum. The melting point of Ni3Ti is 1940 K, it is the highest temperature.