Precipitation in 9Ni-12Cr-2Cu maraging steels
- Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Physics
- Univ. de Rouen, Mont Saint Aignan (France). Lab. de Microscopie Ionique
Two maraging steels with the compositions 9Ni-12Cr-2Cu-4Mo (wt%) and 9Ni-12Cr-2Cu and with small additions of Al and Ti were investigated using atom probe field ion microscopy. Tomographic atom probe investigations were performed to clarify the spatial distribution of elements in and close to the precipitates. Materials heat treated at 475 C for 5, 25 min, 1, 2, 4 and 400 h were analyzed. Precipitates in the Mo-rich material were observed already after 5 min of aging, while in the material without MO, precipitation started later. In both materials precipitation begins with the formation of Cu-rich particles which work as nucleation sites for a Ni-rich phase of type Ni{sub 3}(Ti,Al). A Mo-rich phase was detected in the Mo-rich steel after 2 h of aging. The distribution of alloying elements in the precipitates, their role in the precipitation process, and the mechanism of hardening in the two materials are discussed.
- OSTI ID:
- 302347
- Journal Information:
- Acta Materialia, Vol. 46, Issue 17; Other Information: PBD: 2 Nov 1998
- Country of Publication:
- United States
- Language:
- English
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