TY - JOUR
T1 - Supersaturation and dissolvable α-Cr phase enable superior oxidation resistance in FeCrNi medium-entropy alloys
AU - Wen, Donghui
AU - Jiang, BeiBei
AU - Huang, Zhaowen
AU - Kong, Fengyu
AU - Jiang, Xionghua
AU - Wang, Anding
AU - Liu, Gang
AU - Wang, Biao
PY - 2023/9/5
Y1 - 2023/9/5
N2 - Increasing Cr content in Fe-based alloys is expected to improve oxidation and corrosion resistances, but its effectiveness always degrades because of the over-doping induced precipitation of harmful σ-FeCr and Cr23C6 phases. In this study, the precipitation and oxidation behaviors of FexCrNi alloys were systematically investigated. It is found that the precipitation behavior could be controlled by adjusting the Cr content. The α-Cr phase precipitates at 800 °C in supersaturated FeCrNi medium-entropy alloy (MEA), while it is absent in Fe3CrNi alloy due to the lower Cr content. FeCrNi MEA shows much better oxidation resistance than Fe3CrNi, the oxidation rate constant of FeCrNi is two to three orders lower than that in the Fe3CrNi alloy. The oxidation activation energy of FeCrNi (545 kJ/mol) is much higher than that of the Fe3CrNi alloy (80 kJ/mol), which can be attributed to the synergistic effects of α-Cr dissolution, high configuration entropy and Cr supersaturation. Unlike σ-FeCr and Cr23C6 in stainless steels, the metastable α-Cr phase can be controllably introduced in FeCrNi as a “Cr resource”, and will dissolve during long-term oxidation to provide the required Cr element for the stabilization of the Cr2O3 scale. These discoveries shed new insights into the innovative design of stainless materials for heat-resistance structural applications. © 2023 Elsevier B.V.
AB - Increasing Cr content in Fe-based alloys is expected to improve oxidation and corrosion resistances, but its effectiveness always degrades because of the over-doping induced precipitation of harmful σ-FeCr and Cr23C6 phases. In this study, the precipitation and oxidation behaviors of FexCrNi alloys were systematically investigated. It is found that the precipitation behavior could be controlled by adjusting the Cr content. The α-Cr phase precipitates at 800 °C in supersaturated FeCrNi medium-entropy alloy (MEA), while it is absent in Fe3CrNi alloy due to the lower Cr content. FeCrNi MEA shows much better oxidation resistance than Fe3CrNi, the oxidation rate constant of FeCrNi is two to three orders lower than that in the Fe3CrNi alloy. The oxidation activation energy of FeCrNi (545 kJ/mol) is much higher than that of the Fe3CrNi alloy (80 kJ/mol), which can be attributed to the synergistic effects of α-Cr dissolution, high configuration entropy and Cr supersaturation. Unlike σ-FeCr and Cr23C6 in stainless steels, the metastable α-Cr phase can be controllably introduced in FeCrNi as a “Cr resource”, and will dissolve during long-term oxidation to provide the required Cr element for the stabilization of the Cr2O3 scale. These discoveries shed new insights into the innovative design of stainless materials for heat-resistance structural applications. © 2023 Elsevier B.V.
KW - Activation energy
KW - Cr2O3
KW - FeCrNi
KW - Medium-entropy alloy
KW - Oxidation
UR - http://www.scopus.com/inward/record.url?scp=85152906850&partnerID=8YFLogxK
UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-85152906850&origin=recordpage
U2 - 10.1016/j.jallcom.2023.170216
DO - 10.1016/j.jallcom.2023.170216
M3 - RGC 21 - Publication in refereed journal
SN - 0925-8388
VL - 954
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
M1 - 170216
ER -