Modification of the passivity of iron based alloys through ion implantation

Miscellaneous · Fri Jan 01 00:00:00 EST 1988

OSTI ID:6754678

Wang, Y F

As an unconventional surface alloying process, ion implantation has been utilized to improve the active-passive behavior and the pitting resistance of martensitic M50 engineering alloy. In a field simulation study, Cr-implantation only at 150 kev to a fluence of 2 {times} 10{sup 17} ions/cm{sup 2} prevented pitting. The best pitting resistance of the steel was obtained with multiple implantations of Cr and Mo. The intermixing effect of high fluence P-implantation into 304 stainless produced an amorphous surface alloy. The removal of the grain boundaries and the uniformity of the resulting structure had a great influence on corrosion properties. REED analysis indicated that the anodic passive films formed on P-implanted 304 stainless steel at 250 mV (SCE) in 0.5M H{sub 2}SO{sub 4} was amorphous. Phosphorus and boron were implanted into 316 stainless steel to study the passivity of 316 stainless. Electrochemical experiments were carried out to evaluate the effects of phosphorus and boron on general and localized corrosion resistance. XPS and auger analyses of the passive films formed on these implanted and unimplanted stainless steels were carried out to study the structure and chemical properties of the passive films. From these investigations, it seems likely that the bipolar mechanism of passivity may explain why the absence of the interfacial barrier oxide layer was responsible for the lack of pitting resistance of the P-implanted 316 stainless. The result of XPS spectra curve fitting carried out for films formed on a P-implanted 316 stainless steel steel indicated that a film rich in bound water only without a proper level of Cr in the film, did not resist Cl{sup {minus}} ion attack. The use of ion implantation as a tool to introduce desirable properties to the alloy was successful for studying the mechanism of passivity.

• Research Organization: State Univ. of New York, Stony Brook, NY (USA)
• OSTI ID: 6754678
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BORON
METALLURGICAL EFFECTS
CHROMIUM
MARTENSITIC STEELS
ION IMPLANTATION
PASSIVITY
MOLYBDENUM
PHOSPHORUS
STAINLESS STEEL-304
STAINLESS STEEL-316
AUGER ELECTRON SPECTROSCOPY
CORROSION RESISTANT ALLOYS
ELECTRON DIFFRACTION
GRAIN BOUNDARIES
PHOTOELECTRON SPECTROSCOPY
PITTING CORROSION
X-RAY SPECTROSCOPY
ALLOYS
AUSTENITIC STEELS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM-NICKEL STEELS
CHROMIUM-NICKEL-MOLYBDENUM STEELS
COHERENT SCATTERING
CORROSION
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
HEAT RESIS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HIGH ALLOY STEELS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
METALS
MICROSTRUCTURE
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NONMETALS
SCATTERING
SEMIMETALS
SPECTROSCOPY
STAINLESS STEELS
STEEL-CR17NI12MO3
STEEL-CR19NI10
STEELS
TRANSITION ELEMENTS
360103* - Metals & Alloys- Mechanical Properties
360105 - Metals & Alloys- Corrosion & Erosion
360106 - Metals & Alloys- Radiation Effects