The new sight to Fe–C system.

The crystalline Fe–C alloy had been the focal point of research in the traditional metallurgical steel industry. However, its corresponding amorphous alloy system had received little attention, with a lack of consensus on the microstructural evolution. Three types of Fe–C unbalanced composite films with different carbon content were fabricated using the magnetron sputtering method. The results indicated that as the carbon content increased, carbon existed in the form of supersaturated solid solution atoms in crystalline Fe, an amorphous Fe–C structure and Fe₃C, respectively. The resistivity of the films in these three carbon types gradually increased from 1.37 × 10⁻⁴ ohm/cm to 4.53 × 10⁻² ohm/cm and then to 5.43 × 10⁻² ohm/cm. Simultaneously, the transmittance gradually increased from 0% to 28% and then to 51%. Upon annealing at 400°C, with the crystallisation of Fe in the low-carbon film, unbalanced carbon atoms were pushed out of the lattice and precipitated as Fe₃C. After annealing at 650°C, the Fe₃C in the high-carbon film decomposed into Fe and C. The as-prepared medium-carbon film displayed commendable corrosion resistance. These findings provided valuable insights for the design and performance development of new materials. [ABSTRACT FROM AUTHOR]