Thermophysical properties of Ni-Ti melts measured by electromagnetic levitation method using static magnetic field

Abstract

The normal spectral emissivity, molar heat capacity at constant pressure, and thermal conductivity of Ni-Ti melts were measured during electromagnetic levitation under a static magnetic field. The emissivity and heat capacity of the Ni-Ti melts were measured under a 3 T static magnetic field. The temperature range for the emissivity measurements was 1240–1839 K, and the temperature range for the heat capacity measurements ranged was 1223–1851 K. The emissivity and heat capacity of the Ni-Ti melts, except for the Ni mole fractions (xNi) of 0 and 0.25, showed without temperature dependence within the experimental temperature range. Furthermore, the heat capacity was larger than the ideal solution over the whole range of compositions. The emissivity of the Ni-Ti melts was discussed based on the Drude model. The temperature dependence of thermodynamic functions, such as enthalpy of mixing, excess entropy, and excess Gibbs energy, were calculated using excess heat capacity. The thermal conductivity of Ni-Ti melts was measured under a static magnetic field of 10 T. The temperature range for the thermal conductivity measurements was 1177–1900 K. The thermal conductivities of the Ni-Ti melts increased with increasing temperature, exhibited a local minimum for xNi = 0.75, and were higher than those calculated using the Wiedemann–Franz laws. This difference in thermal conductivity was discussed by considering the contribution of atomic vibrations.