CROSS-SECTIONAL TRANSMISSION ELECTRON-MICROSCOPY STUDY OF PHASE-TRANSFORMATIONS AT TIN FILM STEEL SUBSTRATE INTERFACES

Cross-sectional transmission electron microscopy (XTEM) was used to investigate the extent of solid-state phase transformations near the interfaces of TiN films and AISI M50, 316L, and 440C steel substrates. An ion-plating system was used to deposit the TiN films with and without an initial Ti underlayer on the substrates, whose carbon concentrations ranged from 0.02 to 1 wt%. All films were produced at 500-degrees-C. XTEM, together with electron-energy-loss spectroscopy (EELS) and convergent-beam electron diffraction, of the interfaces indicated that (a) the ion-plated Ti underlayers transform into a TiC phase on high-carbon steel substrates and into a delta'-TiN phase on low-carbon steel substrates, and (b) without a Ti underlayer, TiN grows as the dominant phase on 440-degrees-C steel substrates.