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Title: Enhanced Corrosion Resistance of Iron-Based Amorphous Alloys

Abstract

Iron-based amorphous alloys possess enhanced hardness and are highly resistant to corrosion, which make them desirable for wear applications in corrosive environments. It was of interest to examine the behavior of amorphous alloys during anodic polarization in concentrated salt solutions and in the salt-fog testing. Results from the testing of one amorphous material (SAM2X5) both in ribbon form and as an applied coating are reported here. Cyclic polarization tests were performed on SAM2X5 ribbon as well as on other nuclear engineering materials. SAM2X5 showed the highest resistance to localized corrosion in 5 M CaCl{sub 2} solution at 105 C. Salt fog tests of 316L SS and Alloy 22 coupons coated with amorphous SAM2X5 powder showed resistance to rusting. Partial devitrification may be responsible for isolated pinpoint rust spots in some coatings.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
913546
Report Number(s):
UCRL-PROC-229951
TRN: US200802%%865
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: 2007 ASME Pressure Vessels and Piping Division Conference, San Antonio, TX, United States, Jul 22 - Jul 26, 2007
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; COATINGS; CORROSION; CORROSION RESISTANCE; FOG; HARDNESS; NUCLEAR ENGINEERING; POLARIZATION; PRESSURE VESSELS; TESTING

Citation Formats

Rebak, R B, Day, S D, Lian, T, Aprigliano, L F, Hailey, P D, and Farmer, J C. Enhanced Corrosion Resistance of Iron-Based Amorphous Alloys. United States: N. p., 2007. Web.
Rebak, R B, Day, S D, Lian, T, Aprigliano, L F, Hailey, P D, & Farmer, J C. Enhanced Corrosion Resistance of Iron-Based Amorphous Alloys. United States.
Rebak, R B, Day, S D, Lian, T, Aprigliano, L F, Hailey, P D, and Farmer, J C. Sun . "Enhanced Corrosion Resistance of Iron-Based Amorphous Alloys". United States. doi:. https://www.osti.gov/servlets/purl/913546.
@article{osti_913546,
title = {Enhanced Corrosion Resistance of Iron-Based Amorphous Alloys},
author = {Rebak, R B and Day, S D and Lian, T and Aprigliano, L F and Hailey, P D and Farmer, J C},
abstractNote = {Iron-based amorphous alloys possess enhanced hardness and are highly resistant to corrosion, which make them desirable for wear applications in corrosive environments. It was of interest to examine the behavior of amorphous alloys during anodic polarization in concentrated salt solutions and in the salt-fog testing. Results from the testing of one amorphous material (SAM2X5) both in ribbon form and as an applied coating are reported here. Cyclic polarization tests were performed on SAM2X5 ribbon as well as on other nuclear engineering materials. SAM2X5 showed the highest resistance to localized corrosion in 5 M CaCl{sub 2} solution at 105 C. Salt fog tests of 316L SS and Alloy 22 coupons coated with amorphous SAM2X5 powder showed resistance to rusting. Partial devitrification may be responsible for isolated pinpoint rust spots in some coatings.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Feb 18 00:00:00 EST 2007},
month = {Sun Feb 18 00:00:00 EST 2007}
}

Conference:
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  • Iron-based amorphous alloys can be more resistant to corrosion than polycrystalline materials of similar compositions. However, when the amorphous alloys are exposed to high temperatures they may recrystallize (or devitrify) thus losing their resistance to corrosion. Four different types of amorphous alloys melt spun ribbon specimens were exposed to several temperatures for short periods of time. The resulting corrosion resistance was evaluated in seawater at 90 C and compared with the as-prepared ribbons. Results show that the amorphous alloys can be exposed to 600 C for 1-hr. without losing the corrosion resistance; however, when the ribbons were exposed at 800more » C for 1-hr. their localized corrosion resistance decreased significantly.« less
  • Several hard, corrosion-resistant and neutron-absorbing iron-based amorphous alloys have now been developed that can be applied as thermal spray coatings. These new alloys include relatively high concentrations of Cr, Mo, and W for enhanced corrosion resistance, and substantial B to enable both glass formation and neutron absorption. The corrosion resistances of these novel alloys have been compared to that of several austenitic alloys in a broad range of synthetic brines, with and without nitrate inhibitor, at elevated temperature. Linear polarization and electrochemical impedance spectroscopy have been used for in situ measurement of corrosion rates for prolonged periods of time, whilemore » scanning electron microscopy (SEM) and energy dispersive analysis of X-rays (EDAX) have been used for ex situ characterization of samples at the end of tests. The application of these new coatings for the protection of spent nuclear fuel storage systems, equipment in nuclear service, steel-reinforced concrete will be discussed.« less
  • The passive film stability of several Fe-based amorphous metal formulations have been found to be comparable to that of high-performance Ni-based alloys, and superior to that of stainless steels, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. Chromium (Cr), molybdenum (Mo) and tungsten (W) provide corrosion resistance; boron (B) enables glass formation; and rare earths such as yttrium (Y) lower critical cooling rate (CCR). The high boron content of this particular amorphous metal also makes it an effective neutron absorber, and suitable for criticality control applications, as discussed in companion publications. Corrosion data formore » SAM2X5 (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}) is discussed here. (authors)« less