The effects of reactive-element, ion-implantation-induced amorphous layers on the oxidation of Co-12Cr and Ni-12Cr alloys
- Georgia Inst. of Tech., Atlanta, GA (United States). School of Materials Science and Engineering
Nickel-chromium (Ni-12Cr, wt.%) and cobalt-chromium (Co-12Cr, wt.%) alloys were ion implanted with 150 keV yttrium to fluences that ranged between 2 {times} 10{sup 16} and 1 {times} 0{sup 17} ions/cm{sup 2}. The influence of the implantation on the microstructure of the alloy was determined. The effect of the highest dose implantation on the alloys` oxidation response at 1,000 C, 48 hr was measured. Both alloys contained an amorphous surface phase as a result of this fluence and one of the effects of oxidation was to recrystallize the amorphized alloy in the first few minutes of oxidation. The lower doses of 2 {times} 10{sup 16} ions/cm{sup 2} were sufficient to cause amorphization of both the Ni-12Cr and the Co-12Cr. The implantation reduced the isothermal mass gain by a factor of 25% for the Ni-12Cr, but had a negligible effect on the Co-12Cr alloy. Short-term oxidation of experiments at 600 C showed via transmission electron microscopy that, in the absence of the yttrium implant, the Ni-12Cr alloy forms NiO in the first minute of oxidation and the Co-12Cr alloy forms CoO and CoCr{sub 2}O{sub 4}. The implanted Ni-12Cr, on the other hand (1 {times} 10{sup 17} Y{sup +}/cm{sup 2}), forms recrystallized Ni-Cr, Y{sub 2}O{sub 3}, and NiO in the near-surface region, while the implanted Co-12Cr alloy forms CoO, CoCr{sub 2}O{sub 4}, and a recrystallized intermetallic alloy from the amorphized region.
- OSTI ID:
- 655368
- Journal Information:
- Oxidation of Metals, Vol. 50, Issue 1-2; Other Information: PBD: Aug 1998
- Country of Publication:
- United States
- Language:
- English
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