Polycrystalline Ni–Zr Alloys: Thermal Expansion, Density, Thermal Diffusivity and Thermal Conductivity

The development of new functional and structural materials constitutes one of the priority areas of modern materials science. Accurate knowledge of the thermal properties of systems under study is important for obtaining new effective multifunctional materials with high practical performance. In this paper, we investigate the effect of the composition of the Ni–Zr system on important thermophysical properties such as heat capacity, thermal expansion coefficient (CTE), and thermal conductivity. The temperature dependences of the thermophysical properties of polycrystalline Ni–Zr samples are considered, and the influence of structure effects on their behavior is discussed. The phase compositions of the alloys were confirmed by X-ray structural analysis. The deviation of density from the additive value reaches 5% and has a pronounced minimum at 50 at % Ni. The CTE curves of the annealed samples show two extremes at nickel concentrations of 77 and 50 at %. Deviations in the CTE values on the concentration curve are typical for samples with concentrations close to the formation of NiZr2 and NiZr intermetallics. The temperature curves of the thermal diffusivity and thermal conductivity of Ni–Zr alloys are non-monotonically. The defective structure of polycrystalline Ni–Zr samples has a noticeable effect on their thermophysical properties.