skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Electrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 90oCElectrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 9

Abstract

An iron-based amorphous metal, Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} (SAM2X5), with very good corrosion resistance was developed. This material was prepared as a melt-spun ribbon, as well as gas atomized powder and a thermal-spray coating. During electrochemical testing in several environments, including seawater at 90 C, the passive film stability was found to be comparable to that of high-performance nickel-based alloys, and superior to that of stainless steels, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. This material also performed very well in standard salt fog tests. Chromium (Cr), molybdenum (Mo) and tungsten (W) provided corrosion resistance, and boron (B) enabled glass formation. The high boron content of this particular amorphous metal made it an effective neutron absorber, and suitable for criticality control applications. This material and its parent alloy maintained corrosion resistance up to the glass transition temperature, and remained in the amorphous state during exposure to relatively high neutron doses.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1046111
Report Number(s):
UCRL-TR-230335
TRN: US201215%%399
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; AMORPHOUS STATE; BORON; BREAKDOWN; CHROMIUM; CORROSION; CORROSION RESISTANCE; CRITICALITY; FOG; GLASS; MOLYBDENUM; NEUTRON ABSORBERS; NEUTRONS; SEAWATER; STABILITY; STAINLESS STEELS; TESTING; TRANSITION TEMPERATURE; TUNGSTEN

Citation Formats

Farmer, J C, Haslam, J, Day, S D, Lian, T, Saw, C K, Hailey, P D, Choi, J S, Rebak, R B, Yang, N, Payer, J H, Perepezko, J H, Hildal, K, Lavernia, E J, Ajdelsztajn, L, Branagan, D J, Buffa, E J, and Aprigliano, L F. Electrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 90oCElectrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 9. United States: N. p., 2007. Web. doi:10.2172/1046111.
Farmer, J C, Haslam, J, Day, S D, Lian, T, Saw, C K, Hailey, P D, Choi, J S, Rebak, R B, Yang, N, Payer, J H, Perepezko, J H, Hildal, K, Lavernia, E J, Ajdelsztajn, L, Branagan, D J, Buffa, E J, & Aprigliano, L F. Electrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 90oCElectrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 9. United States. doi:10.2172/1046111.
Farmer, J C, Haslam, J, Day, S D, Lian, T, Saw, C K, Hailey, P D, Choi, J S, Rebak, R B, Yang, N, Payer, J H, Perepezko, J H, Hildal, K, Lavernia, E J, Ajdelsztajn, L, Branagan, D J, Buffa, E J, and Aprigliano, L F. Wed . "Electrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 90oCElectrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 9". United States. doi:10.2172/1046111. https://www.osti.gov/servlets/purl/1046111.
@article{osti_1046111,
title = {Electrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 90oCElectrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 9},
author = {Farmer, J C and Haslam, J and Day, S D and Lian, T and Saw, C K and Hailey, P D and Choi, J S and Rebak, R B and Yang, N and Payer, J H and Perepezko, J H and Hildal, K and Lavernia, E J and Ajdelsztajn, L and Branagan, D J and Buffa, E J and Aprigliano, L F},
abstractNote = {An iron-based amorphous metal, Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} (SAM2X5), with very good corrosion resistance was developed. This material was prepared as a melt-spun ribbon, as well as gas atomized powder and a thermal-spray coating. During electrochemical testing in several environments, including seawater at 90 C, the passive film stability was found to be comparable to that of high-performance nickel-based alloys, and superior to that of stainless steels, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. This material also performed very well in standard salt fog tests. Chromium (Cr), molybdenum (Mo) and tungsten (W) provided corrosion resistance, and boron (B) enabled glass formation. The high boron content of this particular amorphous metal made it an effective neutron absorber, and suitable for criticality control applications. This material and its parent alloy maintained corrosion resistance up to the glass transition temperature, and remained in the amorphous state during exposure to relatively high neutron doses.},
doi = {10.2172/1046111},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Apr 25 00:00:00 EDT 2007},
month = {Wed Apr 25 00:00:00 EDT 2007}
}

Technical Report:

Save / Share:
  • Several Fe-based amorphous metal formulations have been identified that appear to have corrosion resistance comparable to, or better than that of Ni-based Alloy C-22 (UNS N06022), based on measurements of breakdown potential and corrosion rate in seawater. Both chromium (Cr) and molybdenum (Mo) provide corrosion resistance, boron (B) enables glass formation, and rare earths such as yttrium (Y) lower critical cooling rate (CCR). Amorphous Fe{sub 48.0}Cr{sub 15.0}Mo{sub 14.0}B{sub 6.0}C{sub 15.0}Y{sub 2.0} (SAM1651) has a low critical cooling rate (CCR) of less than 80 Kelvin per second, due to the addition of yttrium. The low CCR enables it to be renderedmore » as a completely amorphous material in practical materials processes. While the yttrium enables a low CCR to be achieved, it makes the material relatively difficult to atomize, due to increases in melt viscosity. Consequently, the powders produced thus far have had irregular shape, which had made pneumatic conveyance during thermal spray deposition difficult.« less
  • We have studied Alloy 22 corrosion and passive film stability in nitrogen-purged Na-K-Cl-NO{sub 3} brines having NO{sub 3}:Cl ratios of 7.4 at 160 C and NO{sub 3}:Cl ratios of 0.5 and 7.4 at 220 C in autoclave experiments under a slight pressure. The experiments were done to show the effect of high nitrate brines on the durability of the Alloy 22 outer barrier of the waste canisters. Ratios of NO{sub 3}:Cl used in this study were lower than expected ratios for the repository environment at these temperatures and atmospheric pressures (NO{sub 3}:Cl > 25), however they were thought to bemore » high enough to inhibit localized corrosion. Localized corrosion occurred on the liquid-immersed and vapor-exposed creviced specimens under all conditions studied. Crevice penetration depths were difficult to quantify due to the effects of deformation and surface deposits. Further characterization is needed to evaluate the extent of localized corrosion. The bulk of the surface precipitates were derived from the partial dissolution of ceramic crevice formers used in the study. At this time we do not know if the observed localized corrosion reflects the corrosiveness of Na-K-Cl-NO{sub 3} solutions at elevated temperature over nine months or if it was an artifact of the experimental protocol. Nor do we know if much more concentrated brines with higher NO{sub 3}:Cl ratios formed by dust deliquescence will initiate localized corrosion on Alloy 22 at 160 and 220 C. Our results are consistent with the conclusion that nitrate concentrations greater than 18.5 molal may be required to offset localized corrosion of Alloy 22 at 160 and 220 C. Stability of the passive film and general corrosion were evaluated on the liquid-immersed and vapor-exposed non-creviced specimens. Elemental depth profiles of the vapor-exposed specimens are consistent with the development of a protective Cr-rich oxide near the base metal. The combined passive film and alloy oxide of the immersed specimens was much thicker than for the vapor-exposed specimens. This may be attributed to the inability to transport reactants away from the surface with limited amount of fluid in the condensate compared to the large reservoir for the liquid-immersed specimens. Elemental depth profiles of the liquid-immersed specimens suggest that Cr(III) and Mo(II) in the passive film are oxidized to Cr(VI) and Mo(VI) and are dissolved in the high nitrate brines, because the alloy oxide layers were enriched with Ni relative to Cr and Mo in the base metal. An alumino-silicate-chloride precipitate was identified on specimens immersed in solutions with a NO{sub 3}:Cl ratio of 0.5 at 220 C. Further characterization is needed to identify all secondary phases. The inability to extract reliable rates from weight loss measurements suggests that other techniques are needed to evaluate long-term general corrosion of Alloy 22.« less
  • This report summarizes both general corrosion of Alloy 22 from 60 to 220 C and the stability of the passive (oxide) film from 60 to 90 C over a range of solution compositions that are relevant to the in-drift chemical environment at the waste package surface. The general corrosion rates were determined by weight-loss measurements in a range of complex solution compositions representing the products of both the evaporation of seepage water and also the deliquescence of dust previously deposited on the waste canisters. These data represent the first weight-loss measurements performed by the program at temperatures above 90 C.more » The low corrosion rates of Alloy 22 are attributed to the protective oxide film that forms at the metal surface. In this report, changes in the oxide film composition are correlated with weight loss at the higher temperatures (140-220 C) where film characterization had not been previously performed. The stability of the oxide film was further analyzed by conducting a series of electrochemical tests in progressively more acidic solutions to measure the general corrosion rates in solutions that mimic crevice or pit environments.« less
  • This report summarizes both general corrosion Alloy 22 from 60 to 220 C and the stability of the passive film from 60 to 90 C over a range of solution compositions that are relevant to the in in-drift chemical environment at the waste package surface. The general corrosion rates were determined by weightloss measurements in a range of complex solutions representing the evaporation of seepage water and more concentrated brines representing brines formed by the deliquescence of dust deposited on the canisters. These data represent the first weightloss measurements performed by the program at temperatures above 90 C. The lowmore » corrosion rates of Alloy 22 are attributed to the protective oxide film that forms at the metal surface. In this report, changes in the oxide composition are correlated with weightloss at the higher temperatures (140 related 140-220 C) where film characterization had not been previously performed. The stability of the oxide film was further analyzed by conducted a series of electrochemical tests in progressively more aggressive acid solutions to measure the general corrosion rates in solutions that mimic crevice or pit environments.« less