TY - JOUR
T1 - An atom probe perspective on phase separation and precipitation in duplex stainless steels
AU - Guo, Wei
AU - Garfinkel, David A.
AU - Tucker, Julie D.
AU - Haley, Daniel
AU - Young, George A.
AU - Poplawsky, Jonathan D.
N1 - Publisher Copyright:
© 2016 IOP Publishing Ltd.
PY - 2016/5/16
Y1 - 2016/5/16
N2 - Three-dimensional chemical imaging of Fe-Cr alloys showing Fe-rich (α)/Cr-rich (α′) phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe-Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100-10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni-Mn-Si-Cu-rich G-phase precipitates form at the α/α′ interfaces in both alloys. For the 2101 alloy, Cu clusters act to form a nucleus, around which a Ni-Mn-Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core-shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby-Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30-36).
AB - Three-dimensional chemical imaging of Fe-Cr alloys showing Fe-rich (α)/Cr-rich (α′) phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe-Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100-10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni-Mn-Si-Cu-rich G-phase precipitates form at the α/α′ interfaces in both alloys. For the 2101 alloy, Cu clusters act to form a nucleus, around which a Ni-Mn-Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core-shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby-Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30-36).
KW - Atom probe tomography
KW - Cu cluster
KW - Fe-Cr alloy
KW - G-phase
KW - phase separation
KW - thermal embrittlement
UR - http://www.scopus.com/inward/record.url?scp=84975087372&partnerID=8YFLogxK
U2 - 10.1088/0957-4484/27/25/254004
DO - 10.1088/0957-4484/27/25/254004
M3 - Article
AN - SCOPUS:84975087372
SN - 0957-4484
VL - 27
JO - Nanotechnology
JF - Nanotechnology
IS - 25
M1 - 254004
ER -