Abstract
The nucleation (to a limited extent), growth and coarsening behavior of Cu-rich precipitates in a concentrated multicomponent Fe-Cu-based steel aged at 500 °C from 0.25 to 1024 h is investigated. The temporal evolution of the precipitates, heterophase interfaces, matrix compositions and precipitate morphologies are presented. With increasing time, Cu partitions to the precipitates, Ni, Al and Mn partition to the interfacial region, whereas Fe and Si partition to the matrix. Coarsening time exponents are determined for the mean radius, 〈R(t)〉, number density, NV(t), and supersaturations, which are compared to the Lifshitz-Slyzov-Wagner (LSW) model for coarsening, modified for concentrated multicomponent alloys by Umantsev and Olson (UO). The experimental results indicate that the alloy does not strictly follow UO model behavior. Additionally, we delineate the formation of a Ni-Al-Mn shell with a stoichiometric ratio of 0.51:0.41:0.08 at 1024 h, which reduces the interfacial free energy between the precipitates and the matrix.
Original language | English (US) |
---|---|
Pages (from-to) | 2073-2088 |
Number of pages | 16 |
Journal | Acta Materialia |
Volume | 56 |
Issue number | 9 |
DOIs | |
State | Published - May 2008 |
Funding
This research is supported by the Office of Naval Research (N00014-03-1-0252), Dr. Julie Christodoulou grant officer. Atom-probe tomographic analyses were performed at the Northwestern University Center for Atom-probe Tomography (NUCAPT), and the LEAP™ tomograph was purchased with funding from the NSF-MRI (DMR-0420532, Dr. Charles Bouldin, monitor) and ONR-DURIP (N00014-0400798, Dr. Julie Christodoulou, monitor) programs. Additionally, the LEAP™ tomograph was enhanced in late April 2006 with a picosecond laser with funding from ONR-DURIP (N0014-06-1-0539, Dr. Julie Christodoulou, monitor). This work made use of Central Facilities supported by the MRSEC Program of the National Science Foundation (DMR-0520513) at the Materials Research Center of Northwestern University. The TEM work was performed in the EPIC facility of NUANCE Center at Northwestern University. NUANCE Center is supported by NSF-NSEC, NSF-MRSEC, Keck Foundation, the State of Illinois, and Northwestern University. We extend our gratitude to Professor Emeritus Morris E. Fine, Research Professor Semyon Vaynman, and Research Assistant Professor Dieter Isheim for discussions, and to D.I. for managing NUCAPT.
Keywords
- Atom-probe tomography
- Coarsening
- Fe-Cu alloy
- Interfacial segregation
- Phase separation
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys