Structure of the surface region of stainless steel: bulk and thin films

DOI: 10.1002/pssb.202100513

Authors: Debi Garai (Diamond Light Source; Amity University) , Axel Wilson (Diamond Light Source) , Ilaria Carlomagno (Universita Roma Tre) , Carlo Meneghini (Universita Roma Tre) , Francesco Carla (Diamond Light Source) , Hadeel Hussain (Diamond Light Source) , Ajay Gupta (Amity University) , Jorg Zegenhagen (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physica Status Solidi (b)

State: Published (Approved)
Published: February 2022
Diamond Proposal Number(s): 22710

Abstract: The surface region of austenitic stainless steel (SS) is investigated by synchrotron X-ray powder diffraction (XRPD) and X-ray absorption near edge structure (XANES) measurements, because its composition and structure is crucial for the corrosion resistance of SS. Grazing incidence XRPD of a polished AISI 304 bulk steel sample show that the near-surface structure is modified. The concentration of the ferrite phase of Fe, a typical minority phase in AISI 304, increases gradually from 10% to 30% when approaching the surface from 150 nm depth. XANES Fe K-edge investigations of ultra-thin, sputter deposited films also reveal much larger ferrite fractions than expected from the austenitic steel composition of the films. Reasons for the increased ferrite fraction in the surface region of bulk steel and thin films are discussed. However, right at the surface, the trend reverses. Analysis of XANES data for an ultra-thin, 4 nm SS film show that 80% of Fe is oxidized and 20% of metallic Fe is present only in austenite structure, suggesting that ferritic iron is preferentially subject to oxidation. The austenitic Fe is located at more than 2 - 3 nm below the surface where the Ni concentration is > 10%.

Journal Keywords: Stainless steel; surface structure; thin films; X-ray near edge structure; grazing incidence X-ray powder diffraction; synchrotron radiation

Diamond Keywords: Alloys

Subject Areas: Materials, Physics


Instruments: I07-Surface & interface diffraction

Other Facilities: P64 at the PETRA III

Added On: 07/02/2022 11:39

Documents:
Physica Status Solidi b - 2022 - Garai - Structure of the surface region of stainless steel bulk and thin films.pdf

Discipline Tags:

Surfaces Earth Sciences & Environment Materials Engineering & Processes Physics Hard condensed matter - structures Corrosion Materials Science interfaces and thin films Engineering & Technology Metallurgy

Technical Tags:

Diffraction Grazing Incidence X-ray Diffraction (GIXD)