Rust Resistance: The rusting of iron and steel can be prevented through the addition of 11% or more chromium. The addition of molybdenum can enhance the corrosion resistance, with a complex interplay between the Cr and Mo atoms. However, if chemical variations exist, corrosion can still occur in localized regions or if the surface layer is mechanically abraded.
Duarte
et al. (p. 372 ) studied the corrosive failure of an iron-based glassy alloy. A combination of atom probe tomography, electron microscopy, and x-ray diffraction was used to build up a near atomistic picture of local variations in the metal as it was heated and allowed to crystallize, and the impact these processes have on the corrosion resistance.
Ultrathin Al 2 O 3 layers on alloys are used as templates for model catalysts, tunneling barriers in electronic devices, or corrosion-resistant layers. The complex atomic structure of well-ordered alumina overlayers on NiAl(110) was solved by surface x-ray diffraction. The oxide layer is composed of a double layer of strongly distorted hexagonal oxygen ions that hosts aluminum ions on both octahedral and tetrahedral sites with equal probability. The alumina overlayer exhibits a domain structure that can be related to characteristic growth defects and is generated during the growth of a hexagonally ordered overlayer (Al 2 O 3 ) on a body-centered cubic (110) substrate (NiAl).