In this paper, the first-principles calculations based on DFT were employd to investigate the elasticity characteristics of AgW20 alloy. The elasticity constants of the single crystals are calculated using the finite strain method and Voigt – Reuss – Hill (VRH) approach. The universal anisortropic index (AU ), shear anisortropic index, orientation dependency of Young’s modulus, bulk modulus were used to characterize elasticity anisortropy behaviors. The calculated elasticity properties of AgW20 alloy show a remarkable elasticity anisortropy for AgW20 alloy.

First-principles calculations based on density functional theory (DFT) are used to calculate the structural, elastic and thermodynamic properties of the supersaturated solid-solution AgNi10 alloy, applied mainly to electrical contact materials. In this work, for the exchange-correlation energy, the generalized gradient approximation (GGA) functional is used. The calculated structural and electronic properties of supersaturated solid-solution AgNi10 alloys show that the occupation of Ni in the Ag lattice is ordered. All single-crystal elastic stiffness constants of the energetically and mechanically optimized stable AgNi10 model are calculated using the finite strain method and using the Voigt-Reuss-Hill approximation. Various anisotropic indices like the universal anisotropic index, shear anisotropic index, directional dependence of Young’s modulus, bulk modulus and others are calculated to study the elastic anisotropy. The strong anisotropy in the elastic properties of AgNi10 was confirmed. Phonon dispersions were carried out, showing that the AgNi10 crystal has dynamic stability. The Debye temperature is calculated from the elastic data by estimating the average sound velocity in the AgNi10. Furthermore, the vibrational thermodynamic properties (free energy, enthalpy, entropy and heat capacity) of AgNi10 are obtained successfully.

The first-step drawing process of the platinum-clad nickel composite bar was numerically simulated using DEFORM 3D finite element analysis software. The Taguchi method was used to study the effect of the first-step drawing parameters (the semi-angle of die α, the friction coefficient between the platinum tube and die μ1, the friction coefficient between the platinum tube and nickel rod μ2 and the outer diameter of the original platinum tube D) on the effective stress of platinum-clad nickel bar. Then, the optimal combination of parameters (D = 7.55 mm, μ1 = 0.2, μ2 = 0.3, α = 3°) was obtained. Furthermore, the results of the deformation behavior, cladding behavior, stress effectiveness and the distribution of the damage of the composite bar using optimization schemes were compared and analyzed with Numerical Simulations 8, which showed the worst result. Meanwhile, the experimental results were in general agreement with the simulation results of optimal combination of parameters, indicating that our simulation results are plausible. This has certain guidance significance to improve the quality of platinum-clad nickel composite wires in actual production.

Platinum-clad nickel composite wires with platinum layer thicknesses of 5 μm and 8 μm were prepared by a cladding drawing process. Oxidation experiments were performed using a muffle furnace at temperatures of 500 °C, 600 °C, 700 °C, and 800 °C for 1 h, 2 h, and 3 h. The oxidized samples were examined for high-temperature oxidation behavior using scanning electron microscopy (SEM) with an energy-dispersive X-ray (EDX) spectrometer attached. The results showed that the interface bond between the platinum cladding and the nickel core wire was serrated and that the thickness of the platinum cladding was not uniform. At low temperatures (500 °C and 600 °C), the diffusion rate of the nickel was low. The composite wire could be used for a short time below 600 °C. When the temperature reached 700 °C and above, the nickel diffused to the surface of the composite wire and was selectively oxidized to form a nickel oxide layer. The research results provide a theoretical reference for the selection of a service temperature for platinum-clad nickel composite wires used as the lead material for thin-film platinum resistance temperature sensors.