Thermophysical properties of $75\mathrm{Ni}$–$15\mathrm{Mo}$–$10\mathrm{Re}$ alloy

The true heat capacity, thermal expansion, thermal conductivity, electrical resistance, and density of NMR-75 alloy ($75$ wt $\%\mathrm{Ni}$, $15$ wt $\%\mathrm{Mo}$, and $10$ wt $\%\mathrm{Re}$) are investigated in a temperature range of $300$–$1300$ K. The enthalpy, mean coefficient of thermal expansion, thermal diffusivity, and Lorentz number are calculated from the obtained experimental data. The measurement results show that a reversible structural transformation occurs in the alloy in a temperature range of $750$–$960$ K. In accordance with the phase diagram, the ternary system of the alloy consists of an $\alpha$-solid molybdenum–nickel solution, which is in equilibrium with a $\beta$-solid rhenium–nickel solution and a $\mathrm{Ni}_4\mathrm{Mo}$ intermetallic compound. On heating the alloy in a temperature range of $750$–$960$ K, the intermetallic compound transforms into the $\alpha$-solid molybdenum–nickel solution with the absorption of heat, while the ordered structure transforms into a disordered one. The thermal effect $\mathcal{Q}=6$ kJ/kg and the activation energy of alloy disordering $E=2.2$ eV are estimated. The transformation proper is regarded as a second-order transition.