Papers by Keyword: Amorphous Film

Abstract: The crystallization mechanisms of sputtered Fe_1-xC_x amorphous thin films for three values of atomic carbon content x = 0.28, 0.30 and 0.32 are directly observed using hot stage transmission electron microscopy. Images recorded sequentially are used to track the change caused by heating. Observations concern the nucleation and the growth of iron carbides and their structural identification. Information is also given about their crystallochemistry. They belong to the family of interstitial carbides with carbon atoms located inside iron Triangular Prisms (TP). They are built either from TP Sheets (TPS) stacks deriving from the cementite θ-Fe₃C or from TP Chains (TPC) arrangements deriving from the Eckström-Adcock Fe₇C₃ carbide. The sharp transition between dominant TPS and dominant TPC carbides formations is illustrated. Nucleation and growth processes of both types of carbides are discussed and focus is put on the TPC crystals. They are the first to be formed whatever carbon content of the specimen and really correspond to the dominant phase for the richest-carbon film. When they are less numerous, they can act as nucleation sites for TPS carbides and it is in situ illustrated during the crystallization of the poorest-carbon film where orientation relationships can be found between the TPC-Fe₇C3 carbide and a TPS carbide close to the Hägg carbide χ-Fe₅C₂ The crystallization of Fe_0.70C_0.30 film corresponds to a particular case where TPC carbides and TPS carbides can coexist with the same composition.

Abstract: Combined amorphous and nanocrystalline films attract an attention due to possibility to improve toughness, wear resistance and other properties which are important in nanomaterials and processes in energy systems. One of the known film fabrication methods is the magnetron sputtering deposition in the presence of an additional external magnetic field with inductions of up to 0.3 T as it was demonstrated by an example of the B4C-TiB2 system. The induction effects on the amorphous films hardness, growth rate and nanocrystallization process were investigated and discussed. The deposition under an additional external magnetic field with induction more than 0.2 T leads to the of nc-inclusions formation as was determined by X-ray diffraction, microdiffraction and high resolution transmission electron microscopy methods. The target and film compositions were determined by energy disperse spectroscopy and Rutherford backscattering spectroscopy. Compared to the target composition, some enrichment by nonmetallic elements (carbon and boron) was fixed in films.