TY - JOUR
T1 - Nanosized Cr-N clustering in expanded austenite layer of low temperature plasma-nitrided Fe-35Ni-10Cr alloy
AU - Xie, Yulin
AU - Miyamoto, Goro
AU - Furuhara, Tadashi
N1 - Funding Information:
This work was supported by JST SPRING, Grant No. JPMJSP2114, the JST “Collaborative Research Based on Industrial Demand” Grant No. JPMJSK1613, Japan and by the Tohoku University Microstructural Characterization Platform in Nanotechnology Platform Project sponsored by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. T.F. and G.M. gratefully acknowledge the financial support provided by the Ministry of Education, Culture, Sports, Science and Technology through Grants-in-Aid for Grant-in-Aid for Scientific Research (A) (Nos. 17H01330, 2017–2019), Grant-in-Aid for Scientific Research (B) (Nos. 19H02473, 2019–2021), Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area) (18H05456, 2018–2022), Grant-in-Aid for Challenging Research (Exploratory)(Nos. 21K18803, 2021–2022), JST FOREST Program (Grant No. JPMJFR203W, Japan).
Publisher Copyright:
© 2022 Acta Materialia Inc.
PY - 2022/5
Y1 - 2022/5
N2 - Expanded austenite (γN) formed by low temperature nitriding of austenitic stainless steel is a N-enriched fcc containing Cr-N short range ordering, but no direct observation of Cr-N clustering has been reported. In the present study, the nanostructure of an Fe-35Ni-10Cr (at%) alloy plasma-nitrided at 673 K was investigated using transmission electron microscopy (TEM) and three-dimensional atom probe (3DAP) technique in this study. Nanosized Cr-N clusters were directly observed in the γN accompanied with strong streaks in selected area diffraction, obvious modulated structure in TEM and Cr-N rich regions observed by 3DAP. Thermodynamic calculations suggested that Cr-N clusters were formed by spinodal decomposition due to a strong Cr-N attractive interaction. The hardness of the γN layer was much higher than that of Fe-N austenite steel, which indicates that the hardness is not only due to nitrogen solid-solution hardening but also to a synergetic effect of the coexistence of Cr and N.
AB - Expanded austenite (γN) formed by low temperature nitriding of austenitic stainless steel is a N-enriched fcc containing Cr-N short range ordering, but no direct observation of Cr-N clustering has been reported. In the present study, the nanostructure of an Fe-35Ni-10Cr (at%) alloy plasma-nitrided at 673 K was investigated using transmission electron microscopy (TEM) and three-dimensional atom probe (3DAP) technique in this study. Nanosized Cr-N clusters were directly observed in the γN accompanied with strong streaks in selected area diffraction, obvious modulated structure in TEM and Cr-N rich regions observed by 3DAP. Thermodynamic calculations suggested that Cr-N clusters were formed by spinodal decomposition due to a strong Cr-N attractive interaction. The hardness of the γN layer was much higher than that of Fe-N austenite steel, which indicates that the hardness is not only due to nitrogen solid-solution hardening but also to a synergetic effect of the coexistence of Cr and N.
KW - Expanded austenite
KW - Short-range ordering
KW - Spinodal decomposition
KW - Surface modification
KW - Three-dimensional atom probe (3DAP)
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U2 - 10.1016/j.scriptamat.2022.114637
DO - 10.1016/j.scriptamat.2022.114637
M3 - Article
AN - SCOPUS:85125470670
SN - 1359-6462
VL - 213
JO - Scripta Materialia
JF - Scripta Materialia
M1 - 114637
ER -