Investigation of Beilby layer and its role in the formation of functional surfaces on Fe-Cr-Al-La alloys

Abstract

<p> The fine structure and elemental distribution in the Beilby layer formed during mechanical polishing of Fe-44%Cr-4%Al-0.3%La alloys’ surface were complexly investigated by the methods of Auger electron spectrometry (AES), scanning electron microscopy (SEM), fast electron diffraction and wavelength dispersive spectrometry (WDS). It was find out that Beilby layer formed during mechanical polishing of ground surface of investigated alloy consists of two zones of the same thickness organically combined with each other. The first (outer) zone with thickness of ~250Å is truly amorphous layer saturated by oxygen and carbon atoms while the second underlying (inner) one of ~350Å thickness, which also is of high concentration of oxygen and carbon, has nanocrystalline (~30Å) structure. The existence of Beilby layer very strongly influences on the oxide scale formation process when oxidizing the investigated alloy at high temperatures (>1100C), as it causes development of corrosion resistant and tribological stabile surface scale. </p>