Effect of P implantation on the corrosion behavior of Fe-Cr alloys

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5524304

Sorensen, N R; Diegle, R B; Picraux, S T; Nelson, G C

We are using ion implantation to study the corrosion/passivation behavior of glassy metals. The implantation process allows us to alter both the structure and composition of the surface. We are investigating P implantation (100 keV) into Fe-Cr alloys at fluences ranging from 2.3 x 10/sup 16/ to 2.5 x 10/sup 17/ P/cm/sup 2/, which induces a crystalline to amorphous structural transition. We are studying the passivation of implanted and unimplanted Fe-Cr alloys in 0.1N H/sub 2/SO/sub 4/ with small (0 to 500 ppM) additions of NaCl. At low Cr (6 at. %) concentrations, P implantation improves passivity at applied passive potentials in the Cl-free electrolyte, but it induces pitting when chlorides are present. The improvement in passivity is manifested as an increase in the passivation rate and an increase in the quality of the film, which resists breakdown by Cl ions if they are added after the equilibrium passive film is established. At high Cr concentrations (18 at. %) there is little benefit of implanting P because the base alloy is able to form a protective film by virtue of the high Cr content. At intermediate Cr concentrations, P implantation to produce an amorphous surface results in a decrease in current density of four orders of magnitude. For an Fe-10Cr alloy, increasing the P concentration causes a progressive change in corrosion morphology from general attack, through pitting, to passivation. During general attack the corrosion film is unprotective and permits uniform corrosion. In the P range where pitting is observed, a three-dimensional oxide film is present that thickens when passivity is observed. 4 refs., 7 figs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5524304
• Report Number(s): SAND-87-1196C; CONF-871027-45; ON: DE88005732
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
360106* -- Metals & Alloys-- Radiation Effects
ALLOYS
AQUEOUS SOLUTIONS
CHARGED PARTICLES
CHLORIDES
CHLORINE COMPOUNDS
CHROMIUM ALLOYS
DISPERSIONS
ENERGY RANGE
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
ION IMPLANTATION
IONS
IRON ALLOYS
IRON BASE ALLOYS
KEV RANGE
KEV RANGE 100-1000
METALLIC GLASSES
MIXTURES
PASSIVATION
PHOSPHORUS ADDITIONS
PHOSPHORUS IONS
SOLUTIONS
SULFURIC ACID