High-temperature oxidation behavior of low-energy high-flux nitrided Ni and Ni–20% Cr substrates

Abstract

Nitridation at low energy-high flux implantation-diffusion has been performed on pure Ni and Ni20Cr substrates in order to study their high temperature oxidation behaviour at 700 and 800° C in synthetic air. The nitridation treatment has led to significant sputtering on pure Ni, but no implanted nitrogen has been detected. On the contrary, the Ni20Cr substrates are able to incorporate nitrogen, with less sputtered surfaces. Porosity is anyhow found on both substrates after the nitridation treatment. No particular difference is found to occur on the oxidation kinetics of Ni specimens but on their scales morphology. On the contrary, in Ni20Cr specimens, oxidation is enhanced mainly upon the first exposure times owing to trapping of chromium by the implanted nitrogen. Furthermore, the expanded austenite γ N layer formed on the nitrided Ni20Cr samples is stable up to 700°C for 24 h, after which evolution towards the nitride precipitation occurs.

Low energy–high flux nitrogen implantation of an oxide-dispersion-strengthened FeAl intermetallic alloy

“…In typical austenitic matrices, nitridation leads to the appearance of a metastable γ N phase [28][29][30].…”

Influence of low energy–high flux nitrogen implantation on the oxidation behavior of AISI 304L austenitic stainless steel

“…Such a morphology has also been shown to occur in nitrided Ni20Cr substrates oxidized at 700 and 800°C. 55 Overall, development of Fe-rich oxides occurs at the lowest temperatures and at the most external zones of the scales, whereas the chromium amount increases at the scale/substrate interface due to outward cation diffusion from the bulk. Besides, the amount of nitrogen decreases with increasing temperature, which is in agreement with the superficial EDS microanalyses of Fig.…”

Influence of Nb and Y on Hot Corrosion Behavior of Ni–Cr-based Superalloys

“…Ni-Cr-based superalloy is one of the most popular Ni-based alloys. Cr is beneficial to the corrosion resistance of Ni-based alloys, profiting from the formation of dense compact Cr 2 O 3 scale, which would restrain further oxidation [15]. Hot corrosion mechanisms of Ni-Cr-based alloys under different simulated corrosion conditions have been also investigated and Cr has been proved effective in slowing down the corrosion of the substrate [16,17].…”