About the Synergetic Influence of Manganese and Silicon on the Oxidation Rate of Chromia Forming Nickel-Based Model Allo
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About the Synergetic Influence of Manganese and Silicon on the Oxidation Rate of Chromia Forming Nickel‑Based Model Alloys at 1050 °C T. Perez1 · S. Mathieu1 · Y. Parsa2 · L. Latu‑Romain2 · Y. Wouters2 · M. Vilasi1 Received: 7 April 2020 / Revised: 26 June 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The oxidation behavior of Si- and/or Mn-Ni-25Cr alloys at 1050 °C in air was studied to provide new insights on the effect of minor additions on chromia-scale growth. Four nickel alloys with and without Si or Mn were prepared. Thermogravimetry and post-oxidation characterizations evidenced that manganese increased, whereas silicon addition decreased chromia growth rate. On the contrary, addition of both Si and Mn to the Ni-25Cr alloy led to an unchanged oxidation rate in comparison with the unalloyed Ni-25Cr material. Oxide scales were characterized by photoelectrochemistry (PEC) to evaluate the role of the additions on the point defects nature. The n and p contributions of chromia forming in air were not changed by Si. On the opposite, Mn modified the scale conducting properties since only n contributions were observed for both chromia and Mn1+xCr2−xO4 spinel oxide with Mn-containing samples. In the latter case, the PEC contribution at ~ 3.2–3.4 eV was allocated to the signature of the Mn1+xCr2−xO4 spinel oxide. These data suggested that manganese enhances and silicon limits grain boundary diffusion in chromia scale as reactive element does. Keywords Ni-Cr alloy · Chromia · Manganese effect · Silicon effect · Isothermal oxidation · Photoelectrochemistry
Introduction Commercial high temperature resistant alloys are generally nickel-based alloys which contain 20–30 wt% chromium in order to make the alloy capable to develop protective chromia scale against oxidation in service. Most are used * S. Mathieu stephane.mathieu@univ‑lorraine.fr 1
CNRS, IJL, University of Lorraine, 54000 Nancy, France
2
CNRS, SIMaP, University Grenoble Alpes, 38000 Grenoble, France
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Oxidation of Metals
at service temperatures not exceeding 900 °C, with a limit temperature of use of 1050 °C–1100 °C associated with chromia oxidation into gaseous chromium trioxide. Nearly, all Ni-Cr commercial alloys dedicated to high-temperature applications contain small amounts of minor alloying additions. Additions of Mn, Si, Ti, Al and also of reactive elements like Y, La, Ce are known to modify the chromia growth rate and to play a role on the oxidation resistance [1, 2] of chromia forming nickel-based alloys. Many studies report their effect on the resistance to isothermal or cyclic oxidation. A few of them gives interest to their consequence on chromia growth rate at the atomic scale [3]. The purpose of the present study is to make an assessment of the role of manganese and/or silicon on the oxidation behavior of Ni-25Cr. Manganese is known to readily form along with chromia a spinel layer at the oxide–gas interface in the first period of the oxidation process [4, 5] or both a
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