DrSubarnaChakravorty

CHAKRAVORTY S, SADIQ S, WEST DRF, 1986, EQUILIBRIA INVOLVING P-PHASES AND SIGMA-PHASES IN NI-CR-AL-MO SYSTEM, MATERIALS SCIENCE AND TECHNOLOGY, Vol: 2, Pages: 110-121, ISSN: 0267-0836

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• Citations: 12

Chakravorty S, West DRF, 1985, Constitution of Ni-rich alloys in Ni–AI–Mo–Ta system at 1273 and 1073 K, Materials Science and Technology (United Kingdom), Vol: 1, Pages: 61-72, ISSN: 0267-0836

An investigation is reported of the constitution of the Ni rich portion of the Ni–Al–Mo–Ta system at 1273 and 1073 K. Alloys containing 85 and 75 at.-% Ni respectively were used for the investigation, their constitution at 1523 K having been previously determined. Electron probe microanalysis, X-ray diffraction, and light microscopy were the main techniques of examination. In the 85 at.-% Ni section of the system, only the γ and γ' phases were present in the composition range extending up to 6 at.% Ta. In the 75 at.% Ni section, the following phases were encountered: γ, γ', δ (based on Ni3Ta), η (based on Ni6TaAl), δ ' (based on NiMo), and " (based on Ni3Mo). For the part of the section having Ta contents greater than about 10 at.-%, the equilibria involving γ γ'η, η and δ changed little from at 1523 K. However, the γ region (based on Ni75Mo25)and the γ+ γ' regions which existed at 1523 K were replaced by regions representing equilibria involving NiMo and Ni3Mo. A reaction γ+δ '⇛ γ'+ δ" is proposed between 1200 and 1073 K. © 1985 Maney Publishing.

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CHAKRAVORTY S, WEST DRF, 1984, THE NI3AL-NI3CR-NI3MO SECTION OF THE NI-CR-AL-MO SYSTEM, JOURNAL OF MATERIALS SCIENCE, Vol: 19, Pages: 3574-3587, ISSN: 0022-2461

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• Citations: 25

CHAKRAVORTY S, WEST DRF, 1984, CONSTITUTION OF NI RICH ALLOYS IN NI-AL-MO-TA SYSTEM AT 1523-K, METAL SCIENCE, Vol: 18, Pages: 207-215, ISSN: 0306-3453

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CHAKRAVORTY S, WEST DRF, 1983, CONSTITUTION OF NI RICH ALLOYS IN NI-MO-TA SYSTEM, METAL SCIENCE, Vol: 17, Pages: 573-580, ISSN: 0306-3453

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CHAKRAVORTY S, WEST DRF, 1983, INTERMETALLIC COMPOUND FORMATION IN THE NI3TA-NI3MO SECTION OF THE NI-TA-MO SYSTEM, JOURNAL OF MATERIALS SCIENCE LETTERS, Vol: 2, Pages: 583-586, ISSN: 0261-8028

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• Citations: 4

Chakravorty S, West DRF, 1980, High-temperature strength of nickel alloys based on γ′-phase, Metals Technology, Vol: 7, Pages: 414-419, ISSN: 0307-1693

An investigation has been made of the influence of tantalum, hafnium, and carbon on the strength of Ni3Al (γ′). Ternary and quaternary alloys have been studied, based on the Ni-Al-Ta and Ni-Al-Hf systems, with aluminium contents in the range ∼20–25 at.-%, tantalum or hafnium contents up to 5 at.-%, and carbon up to 1·4 at.-%. These alloys consisted wholly or predominantly of γ′, with compositions on the (Al + Ta, Hf)-rich side of γ′-stoichiometry. Also, a multicomponent alloy (Ni-Al-Ta-Hf-W-Cr-Co-Zr-B-C) on the nickel-rich side of stoichiometry has been studied. Structural observations have been made, together with measurements of yield stress and of secondary-creep rates at temperatures up to ∼1000°C. Tantalum and hafnium conferred substantial solid-solution strengthening on γ′ however, with carbon additions, carbide formation significantly reduced the matrix strength as a result of solute depletion. The strength and creep resistance of the multicomponent alloy consisting of γ + γ′ + carbide were improved by heat treatment. © 1980, The Metals Society. All rights reserved.

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• Citations: 4