The influence of thermal treatment on the chemistry and structure of grain boundaries in inconel 600

Was, Gary S.; Tischner, H.; Latanision, R. M.

doi:10.1007/bf02643684

Cited by 91 publications

(21 citation statements)

References 30 publications

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“…The sensitization of stainless steels and Ni-based alloys due to the formation of (Fe, Cr) 23 C 6 , which results in the depletion of Cr in the surrounding matrix, has been widely studied, both theoretically and experimentally. [31][32][33][34][35] It was shown that the extent of Cr depletion in the surrounding matrix depends on the size, distribution, and volume fraction of the carbide and the post-heat-treatment practice. Figure 12 demonstrates the devitrification of SAM 1651 and the formation of the nanometer-sized Cr-depleted zones associated with carbide precipitation.…”

Section: Effect Of Heat Treatment On Composition Of Sam 1651mentioning

confidence: 99%

Devitrification of Fe-Based Amorphous Metal SAM 1651: A Structural and Compositional Study

Payer

2009

Metall Mater Trans A

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The effect of heat treatment on the chemistry and structure of an Fe-based bulk metallic glass (BMG) Fe 48 Cr 15 Mo 14 C 15 B 6 Y 2 (SAM 1651) was examined experimentally. Chemical segregation was found in the as-received material, with islands 10 to 200 nm in diameter enriched in Y, Mo, and C and depleted in Fe and Cr, with respect to the surrounding matrix. Heat treatment in the range of 600°C to 800°C caused partial devitrification of the BMG with the formation of nanocrystalline (Fe, Cr) 23 C 6 and (Fe, Cr) 7 C 3 carbides in a matrix of the remaining amorphous phase. The devitrification process followed a primary crystallization route. Amorphous particlefree zones (PFZs) in the devitrified material were found, corresponding to the Y-Mo-rich islands in the fully amorphous SAM 1651. The formation of Cr-rich carbide during devitrification caused the formation of nanometer-sized Cr-depleted zones surrounding the carbide particles, which is detrimental to the corrosion performance of the alloy after thermal exposure.

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Section: Effect Of Heat Treatment On Composition Of Sam 1651mentioning

confidence: 99%

Devitrification of Fe-Based Amorphous Metal SAM 1651: A Structural and Compositional Study

Payer

2009

Metall Mater Trans A

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“…For this purpose, the size of the chromium-depleted zone and the level of Cr were considered together as an equivalent Cr-depleted-zone width, as suggested by Was et al [27] The area of the depletion profiles below various Cr concentrations was calculated. This area was then divided by the bulk Cr concentration to obtain an equivalent width of the Cr-depleted zone (in nanometers).…”

Section: Grain-boundary Chemistry and Intergranular Corrosionmentioning

confidence: 99%

Grain-boundary chemistry and intergranular corrosion in alloy 825

Pan,

Dunn,

Cragnolino

et al. 2000

Metall Mater Trans A

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Alloy 825, a former candidate material for radioactive high-level waste containers, was investigated to assess its thermal stability and the time-temperature conditions for sensitization. Alloy specimens with a carbon content of 0.01 wt pct in the mill-annealed (MA) and solution-annealed (SA) conditions were studied after thermal exposure to temperatures ranging from 600 ЊC to 800 ЊC for periods of up to 1000 hours. Sensitization was evaluated by using corrosion tests that were correlated to grainboundary chemistry analyses. Sensitized microstructures were found to contain M 23 C 6 -type carbides and a chromium-depleted region in the vicinity of the grain boundaries. Thermal aging at 700 ЊC for 100 hours resulted in the highest sensitization. While heat treatment at 640 ЊC showed a progressive development of sensitization with time, healing was found to occur after aging at 800 ЊC for 100 hours. The degree of sensitization, quantified by an equivalent chromium-depleted-zone size, correlates well with the corrosion rate in the nitric acid test. Thermodynamic models were used to calculate the interfacial chromium concentration, chromium depletion profile, and the depleted-zone width. Comparisons between experimental measurements and model calculations indicate that reliable prediction depends on the selection of key model parameters.

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“…The experimental data were taken from three sources, i.e., Was et al (1981), Was and Kruger (1985) and Hall and Briant (1985). These sources are in a fairly reasonable, but not fully quantitative, agreement with each other.…”

Section: Predicting Depletion Profiles At Grain Boundariesmentioning

confidence: 99%

“…The first direct evidence of grain boundary chromium depletion in alloy 600 was reported by Was et al (1981) who found that the depth of depletion (i.e., the difference between the lowest chromium content in the depleted zone and the bulk/matrix chromium content) increased for aging times up to 10 hours at 700°C. Continued aging at 700°C resulted in healing of the GBCD, although complete recovery was not evident before 100 hours of aging.…”

Section: Southwest Research Institutementioning

confidence: 99%