Extreme precipitation strengthening in ion-implanted nickel
- Sandia National Laboratories, Albuquerque, New Mexico 87185-1056 (United States)
Precipitation strengthening of nickel was investigated using ion-implantation alloying and nanoindentation testing for particle separations in the nanometer range and volume fractions extending above 10{percent}. Ion implantation of either oxygen alone or oxygen plus aluminum at room temperature was shown to produce substantial strengthening in the ion-treated layer, with yield strengths near 5 GPa in both cases. After annealing to 550&hthinsp;{degree}C the oxygen-alone layer loses much of the benefit, with its yield strength reduced to 1.2 GPa, but the dual ion-implanted layer retains a substantially enhanced yield strength of over 4 GPa. Examination by transmission electron microscopy showed very fine dispersions of 1{endash}5 nm diameter NiO and {gamma}-Al{sub 2}O{sub 3} precipitates in the implanted layers before annealing. The heat treatment at 550&hthinsp;{degree}C induced ripening of the NiO particles to sizes ranging from 7 to 20 nm, whereas the more stable {gamma}-Al{sub 2}O{sub 3} precipitates were little changed. The extreme strengthening we observe is in semiquantitative agreement with predictions based on the application of dispersion-hardening theory to these microstructures. {copyright} {ital 1999 American Institute of Physics.}
- OSTI ID:
- 698831
- Journal Information:
- Journal of Applied Physics, Vol. 86, Issue 11; Other Information: PBD: Dec 1999
- Country of Publication:
- United States
- Language:
- English
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