Experimental and thermodynamic study of tantalum-containing iron-base alloys reinforced by carbides: Part II — Case of (Fe, Ni, Cr)-base austenitic steels

Berthod, Patrice; Hamini, Yassin; Héricher, Ludovic; Aranda, Lionel

doi:10.1016/j.calphad.2007.01.008

Cited by 13 publications

(5 citation statements)

References 15 publications

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“…As in the earlier studied Cr-rich alloys based on Co [22] or on Fe [23,24] , the TaC carbides obtained here have appeared in the last zones to solidify and they are essentially eutectic with close imbrication with matrix, and of the script-like morphology. Good initial interdendrites and intergrains cohesion at high temperature can be thus expected on long time for delaying the transition from secondary state of creep to the tertiary state.…”

Section: Discussionsupporting

confidence: 82%

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As-Cast Microstructures of High Entropy Alloys Designed to Be TaC-Strengthened

Berthod

2022

j. of met. mater. res.

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In this work two new alloys were obtained by extrapolation from a wellknown high entropy alloy, the equimolar CoNiFeMnCr one. This was doneby the addition of carbon and of tantalum, Ta being one of the strongestMC-former elements. They were produced by conventional casting underinert atmosphere. The obtained microstructures were characterized by X-raydiffraction, metallography, electron microscopy, and energy dispersionspectrometry. Their hardness was also measured by hardness indentation.In parallel, the original CoNiFeMnCr alloy was also synthesized andcharacterized for comparison. The reference HEA alloy is single-phasedwith an austenitic structure, while the two {Ta, C}-added alloys aredouble-phased, with an austenitic matrix and interdendritic script-likeTaC carbides. The matrixes of these HEA/TaC alloy are equivalent toan equimolar CoNiFeMnCr alloy to which 2 wt.% Ta is present in solidsolution. The presence of the TaC carbides caused a significant increase inhardness which suggests that the HEA/TaC alloys may be mechanicallystronger than the HEA reference alloy at high temperature.

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Section: Discussionsupporting

confidence: 82%

“…In that way, the 20 wt.% Ni in presence of 20 wt.%Cr is probably compensated by the 20 wt.% Co and 20 wt.% Fe more favorable to the formation of TaC. Indeed, these two last elements did not cause earlier problem of predominance of chromium carbides on TaC carbides in Cr-rich alloys for which they were the base elements [22][23][24] .…”

Section: Discussionmentioning

confidence: 95%

As-Cast Microstructures of High Entropy Alloys Designed to Be TaC-Strengthened

Berthod

2022

j. of met. mater. res.

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“…Therefore TaC carbides can be easily obtained in Cr-rich cobalt alloys instead of chromium carbides [4]. It is also true in chromiumrich ferritic or austenitic alloys based on (Fe,Cr) or (Fe,Ni,Cr) [5,6] but TaC are more difficult to obtain in (Ni,Cr)-based alloys [7].…”

Section: Introductionmentioning

confidence: 97%

High temperature properties of several chromium-containing Co-based alloys reinforced by different types of MC carbides (M=Ta, Nb, Hf and/or Zr)

Berthod¹

2009

Journal of Alloys and Compounds

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a b s t r a c tFive cast cobalt alloys based on Co-8Ni-30Cr-0.4/0.45C and containing Ta, Nb, Hf and/or Zr were studied by metallography in the as-cast condition and after treatments at 1300 • C. The obtained MC carbides were all interdendritic with a eutectic script-like morphology. For similar carbon contents, the HfC carbides are the most developed in the as-cast microstructure and the most stable at 1300 • C. As-cast, the TaC carbides are less developed than the former and they tend to become more fractioned and less present in microstructure at 1300 • C. The NbC carbides, which have initially the same morphology and the same fraction as TaC, rapidly dissolve at 1300 • C. The cobalt alloys containing HfC or TaC are chromia -forming at 1300 • C. The NbC-containing alloy catastrophically oxides after only few hours at 1300 • C. The average hardness is the highest for the HfC-containing alloy and the lowest for the NbC-containing alloy.

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“…Numerous iron-based alloys rich in Al 14,15 , or chromium 16,17 , Cr-rich nickel-based [18][19][20][21] and cobalt-based alloys 22,23 (notably including the well-known Mar-M Co-based superalloy 24 , for example), are also strengthened by TaC. Thanks to its stability at high temperature, much higher than the chromium carbides, tantalum carbides are considered as very efficient particles for creep-resistance for long times.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic and experimental study of 30 wt-%Cr-containing {Co, Fe or Ni}-based alloys with very high contents in Ta and C

Berthod

Corona

2016

Canadian Metallurgical Quarterly

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TaC carbides are among the most efficient particles for reinforcing cast refractory alloys and superalloys against mechanical stresses at temperature as high as 1000°C and over. The most common TaC-strengthened superalloys contain less than 0.5 wt.%C and 5wt.%Ta. Enriching alloys in C and Ta may lead to higher fractions in TaC and therefore possibly to higher mechanical properties for service in hot conditions. The present work explores the microstructures achievable in a cobalt alloy, a nickel one and an iron one, by the introduction of 1 wt.%C and 15wt.%Ta, first using thermodynamic calculations and second by real elaboration. High fractions in TaC were effectively obtained, script-like eutectic ones, but also blocky preeutectic ones less efficient for reinforcement. These blocky TaC, the formation of which was explained by thermodynamic calculations, tend to aggregate together in some locations, with an overconsumption of Ta. However, some disagreements were noticed between predictions with thermodynamic calculations and as-cast microstructures.

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Experimental and thermodynamic study of tantalum-containing iron-base alloys reinforced by carbides: Part II — Case of (Fe, Ni, Cr)-base austenitic steels

Cited by 13 publications

References 15 publications

As-Cast Microstructures of High Entropy Alloys Designed to Be TaC-Strengthened

As-Cast Microstructures of High Entropy Alloys Designed to Be TaC-Strengthened

High temperature properties of several chromium-containing Co-based alloys reinforced by different types of MC carbides (M=Ta, Nb, Hf and/or Zr)

Thermodynamic and experimental study of 30 wt-%Cr-containing {Co, Fe or Ni}-based alloys with very high contents in Ta and C

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