Structure and phase composition of films Fe–Si–B-Cu–Nb and Fe–Si–B–Ni–Mo

Abstract

The influence of modernized three-electrode ion-plasma sputtering of a complex target based on the Fe-Si-B system with Cu, Nb or Ni, Mo additives on the structure and properties of sputtered films has been studied. The formation of amorphous and nanocrystalline phases in the films was detected. The size of the coherent scattering region in the film 73 at.% Fe, 15.8 at.% Si, 7.2 at.% B, 4 at.% Cu, 4 at.% Nb (Fe75SiBCuNb) was 1.6 nm. The film 78.5 at.% Fe, 6 at.% Si, 14 at.% B, 1.5 at.% Ni, 1.5 at.% Mo (Fe78.5SiBNiMo) the size of the coherent scattering region was 12 nm. The thermal stability of the resulting metastable states of the films was investigated. The temperatures of the beginning and end of the decay of the emerging metastable states were estimated from the points on the temperature dependence at which an irreversible decrease in electrical resistance begins. The structure of Fe75SiBCuNb films demonstrates stability up to a temperature of 773 K. For these films, the temperature coefficient of resistance is (-0.00021)·1/K. Fe78.5SiBNiMo films are stable up to 703 K and have a temperature coefficient of resistance (-0.000009)·1/K. At 773 K for the Fe75SiBCuNb composition and 703 K for the Fe78.5SiBNiMo composition, the beginning of the decomposition of metastable structures is observed with the appearance of a supersaturated α-Fe solid solution. The temperature dependence of achieving the maximum value of the relative change in electrical resistance ((R/R0) was used to estimate the activation energy of the decay processes of the original metastable structures. The activation energy values obtained by the Kissinger method are 10400 ± 1200 K. This value is four times lower than the activation energy values (43000 K) in the Fe40Ni40P14B6 alloy quenched from the liquid state. This can be explained by geometric factors and the practical two-dimensionality of films compared to quenched foils. The work determined the conditions for obtaining films with low values of the temperature coefficient of electrical resistance (-0.000009)·1/K and coercive force (HC ~ 11 A/m).