期刊
ACTA MATERIALIA
卷 179, 期 -, 页码 296-307出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2019.08.042
关键词
Maraging steel; Precipitation hardening; Microstructure evolution; Mechanical behavior
资金
- Youth Innovation Promotion Association of Chinese Academy of Sciences [2017233]
- Innovation Project of Institute of Metal Research [2015-ZD04]
- National Natural Science Foundation of China Research Fund for International Young Scientists [51750110515]
- National Natural Science Foundation of China [51472249]
Development of precipitation strengthening steels with ultrahigh strength and high ductility requires thorough understanding of nanoscale precipitation mechanisms. In this study, atom probe tomography (APT), HRTEM and first-principles calculations were used to reveal an interesting co-precipitation mechanism of Ni3Ti and Mo-rich nanoparticles in a 2.5 GPa grade maraging steel. The Ni-Ti rich clusters preferentially nucleate from the supersaturated solid solution and grow into Ni3Ti with extension of aging time, meanwhile the rejection of Mo atoms leads to heterogeneous precipitation of Mo-rich nanoparticles adjacent to the Ni3Ti particles and finally forms a core-shell structure along with Ni3Ti phase. Calculations of interaction energy between alloying elements in different aging process exhibit that the preferential formation of Ni-Ti rich cluster is due to the low interaction energy between Ni and Ti atoms, however, the Ni-Ti cluster is only a transitional phase, and when stable Ni3Ti is formed, Mo atoms are rejected from Ni3Ti to form a core-shell structure along with Ni3Ti precipitates. Finally, four modified theoretical prediction models are introduced to describe the yield strength as a function of microstructure and precipitates characteristics of the experimental steel. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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