The isotherms at different temperatures. The open symbols are the previous theoretical data from quasiharmonic Debye approximation (see Ref. 31).
The bulk modulus B and its pressure derivative B′ of NiTi versus temperature at zero pressure.
The volume at different pressures (1 bar and from 5 GPa to 40 GPa with 5 GPa interval) versus temperature, The insert of the figure is the normalized volume ratio as a function of temperature at 1 bar. The open squares are previous theoretic data (see Ref. 31).
Thermal expansivity of NiTi as a function of temperature from 1 bar up to 40 GPa.
The pair-correlation functions g(r) at P = 1 bar and T = 298, 1800, 1900, and 2000 K. At T = 298 K, the g(r) shows distinct peaks, indicating a solid structure. At T = 1800 K the configuration tends to liquefy. At T = 1900 and 2000 K, the smooth curve of the g(r) emphasizes a liquid structure.
(Color online) The configuration of solid-liquid coexistence phase at 1 bar; the purple and yellow spheres represent Ni and Ti atoms, respectively.
Density profile for the coexistence configuration. The solid phase is identified by periodic oscillations of the density, while the density of the liquid phase fluctuates with much smaller amplitude. (a) The moving of interfaces toward liquid part when T < T m; (b) the initial configuration; (c) the moving of interfaces toward solid parts when T > T m.
Calculated melting curves from one-phase (solid squares) and two-phase (solid circles) simulations (the solid and dashed lines are the melting data fitted with Simon equation). The solid triangles with error bar represent the experimental data for pure Ni and Ti (see Ref. 4), and the theoretical data for Ni (see Ref. 53). The insert of the figure is the superheating as a function of pressure.
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