The influence of ion-implanted yttrium on the selective oxidation of chromium in Co-25 wt. % Cr
- Univ. of California, Berkeley (USA)
Specimens of Co-25 wt.% Cr, Co-25 wt.% Cr-1 wt.%Y, and yttrium-implanted Co-25 wt.% Cr alloy were oxidized at 100{degree}C in 1 atm O{sub 2}. The implantation dosage ranged between 10{sup 16} to 10{sup 18} ions/cm{sup 2}. The unimplanted binary alloy oxidized to a duplex Co-rich scale, but the Y-containing ternary alloy formed a continuous Cr{sub 2}O{sub 3} layer. When the implantation dosages were lower than a nominal 10{sup 18} ions/cm{sup 2}, the alloy failed to develop a similar continuous Cr{sub 2}O{sub 3} layer as that observed with the Y-containing alloy. A temporarily stable external Cr{sub 2}O{sub 3} scale was formed on the most heavily implanted specimen (1 {times} 10{sup 18} Y{sup +}/cm{sup 2}). This Cr{sub 2}O{sub 3} scale consisted of very fine-grained oxide, which is permeable to the outward transport of Cr and Co. Internal oxidation pretreatment of the ion-implanted specimens converting the Y metal to its oxide prior to the oxidation experiment, can enhance the development of an external Cr{sub 2}O{sub 3} scale, but this scale is also unstable. Results suggest that the selective oxidation of chromium in an ordinarily non-Cr{sub 2}O{sub 3}-forming alloy can be due to the reactive element oxides acting as preferential nucleation sites on the alloy surfaces, but the subsequent growth of these scales may require a continuous supply of reactive elements in the alloy.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5423966
- Journal Information:
- Oxidation of Metals; (USA), Vol. 29:1-2; ISSN 0030-770X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHROMIUM
OXIDATION
CHROMIUM ALLOYS
ION IMPLANTATION
COBALT BASE ALLOYS
YTTRIUM
METALLURGICAL EFFECTS
YTTRIUM ALLOYS
CHROMIUM OXIDES
ION MICROPROBE ANALYSIS
MASS SPECTROSCOPY
SCALING
SCANNING ELECTRON MICROSCOPY
ALLOYS
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
CHROMIUM COMPOUNDS
COBALT ALLOYS
ELECTRON MICROSCOPY
ELEMENTS
METALS
MICROANALYSIS
MICROSCOPY
NONDESTRUCTIVE ANALYSIS
OXIDES
OXYGEN COMPOUNDS
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
360105* - Metals & Alloys- Corrosion & Erosion
360102 - Metals & Alloys- Structure & Phase Studies