TY - JOUR
T1 - Atomic-scale understanding of solute interaction effects on grain boundary segregation, precipitation, and fracture of ultrahigh-strength maraging steels
AU - Niu, M.C.
AU - Chen, C.J.
AU - Li, W.
AU - Yang, K.
AU - Luan, J.H.
AU - Wang, W.
AU - Jiao, Z.B.
PY - 2023/7/1
Y1 - 2023/7/1
N2 - Understanding the fundamental mechanisms of embrittlement and de-embrittlement is crucial for the development of strategies toward advanced steels with improved performance. In this study, the solute interaction effects on grain boundary (GB) segregation, precipitation, and fracture of Fe–Ni–Ti–(Mo) maraging steels were systematically investigated through a combination of experimental and theoretical techniques, including scanning transmission electron microscopy, atom probe tomography, and first-principles calculations. Our results reveal that the Fe–Ni–Ti maraging steel suffers from serious intergranular embrittlement and the mechanism is related to the formation of coarse Ni3Ti precipitates and associated precipitate-free zones (PFZs) at GBs, which facilitate the crack initiation and growth along the GBs. Interestingly, adding Mo to the maraging steel effectively suppresses the intergranular embrittlement, thereby substantially improving the ductility. Atomistic analyses reveal that Mo de-embrittles the GBs by reducing the segregation of Ni and Ti, which substantially inhibits the formation of coarse Ni3Ti precipitates and PFZs at the GBs, thereby alleviating their harmful impact on the GB cracking. In addition, the Mo segregation enhances the GB cohesion, which may play a minor role in suppressing the GB fracture. © 2023 Acta Materialia Inc.
AB - Understanding the fundamental mechanisms of embrittlement and de-embrittlement is crucial for the development of strategies toward advanced steels with improved performance. In this study, the solute interaction effects on grain boundary (GB) segregation, precipitation, and fracture of Fe–Ni–Ti–(Mo) maraging steels were systematically investigated through a combination of experimental and theoretical techniques, including scanning transmission electron microscopy, atom probe tomography, and first-principles calculations. Our results reveal that the Fe–Ni–Ti maraging steel suffers from serious intergranular embrittlement and the mechanism is related to the formation of coarse Ni3Ti precipitates and associated precipitate-free zones (PFZs) at GBs, which facilitate the crack initiation and growth along the GBs. Interestingly, adding Mo to the maraging steel effectively suppresses the intergranular embrittlement, thereby substantially improving the ductility. Atomistic analyses reveal that Mo de-embrittles the GBs by reducing the segregation of Ni and Ti, which substantially inhibits the formation of coarse Ni3Ti precipitates and PFZs at the GBs, thereby alleviating their harmful impact on the GB cracking. In addition, the Mo segregation enhances the GB cohesion, which may play a minor role in suppressing the GB fracture. © 2023 Acta Materialia Inc.
KW - Grain boundary embrittlement
KW - Grain boundary segregation
KW - Maraging steel
KW - Precipitation
UR - http://www.scopus.com/inward/record.url?scp=85154534705&partnerID=8YFLogxK
UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-85154534705&origin=recordpage
U2 - 10.1016/j.actamat.2023.118972
DO - 10.1016/j.actamat.2023.118972
M3 - RGC 21 - Publication in refereed journal
SN - 1359-6454
VL - 253
JO - Acta Materialia
JF - Acta Materialia
M1 - 118972
ER -