Phase composition and physical properties of high-carbon Fe-C films

The formation conditions for metastable structures and phase transformations during the heat treatment of high-carbon Fe-C films (20-84 at.% C) are studied by X-ray analysis, electron microscopy, measuring of the relative electrical resistance, and magnetic measuring. The films of a Fe-C system are fabricated by modernized three-electrode ion-plasma sputtering. As shown, the films with 20-31% C in. an initial state have an X-ray amorphous structure; the films with 40-60% C have an amorphous structure. The transformation of a film structure from an amorphous state to an equilibrium one during an annealing occurs through the formation and subsequent decomposition of the intermediate metastable h.c.p. phase with a variable content. The causes and mechanism of high values of magnetic-rigidity characteristics in obtained high-carbon Fe-C films at optimal compositions and heat-treatment regimes are suggested. The precise values of temperature coefficient of resistance are determined for Fe-C films.