Investigation of the Amorphization of iron and austenitic stainless steel films by supersaturation with Boron, Carbon, Nitrogen and Oxygen

Abstract

This work investigates the amorphization behavior of Fe-based alloys and the formation of metallic glasses based on conventional.It is well known, that small additions of alloying elements such as boron, oxygen, carbon, or nitrogen, have crucial influence on the deformation behavior, on the mechanical and tribological properties of steel. The modification of the steel properties are originated in strong interactions between interstitial alloying atoms and defects such as vacancies, interstitials and grain boundaries. Thus, it is necessary to determine in more detail the effects of individual alloying elements on the Fe and steel properties.One of the more recent works, which attempts to develop a theoretical model of the binary Fe-C/Fe-N system, was published by Byeng-Joo Lee. By using a modified embedded-atom method (MEAM), he calculated an interatomic potential for the Fe-C/Fe-N binary system and predicted the physical properties of a hypothetical NaCl-type FeC/FeN phase. This was the impulse to investigate the Fe-C system for high-carbon concentrations to get a comprehensive sketch of carbide formation and to be able to amorphize conventional steels of the AISI 3xx family.As a matter of fact, a cubic FeC phase, which was prepared by means of new developed pulsed laser deposition - the Sequential Target Pulsed Laser Deposition (STPLD), is found and its parameters are found very close to those as predicted by Lee. Otherwise, the magnetron-sputtering technique is exposing as unsuitable to form cubic FeC structures and various carbides are observed instead.However, reactive magnetron-sputtering is showing the formation of an amorphous and soft ferromagnetic phase in a wide range of the processing parameters and for different reactive gases (e.g. CH4, N2 and O2). These films exhibit quasi-metallic glass behavior and the origin and magnitude of magnetism can be deduced from a disordered Ni3C phase for carburized/nitrided films, and from a disordered NiFe2O4 for oxidized films.Furthermore, the transferability to other deposition techniquesis investigated and a generalized nucleation model is presented.