Microstructural characterization of multicomponent Nb-Ti-Si-Cr-Al-X alloys

Tewari, R.; Song, Hyun Keun; Vasudevan, Vijay K.; Chatterjee, Amit

doi:10.1007/bf02586101

Cited by 17 publications

(12 citation statements)

References 9 publications

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“…The presence of these elements increases the volume fraction of the phase from nearly negligible volume fraction to 30 pct. [7] Therefore, it can be inferred that in these alloy series, the presence of Cr higher than 9 pct along with Hf and Zr (Hf + Zr 6 pct) causes a copious presence of the Laves phase. The other elements that influence the development of microstructures are Ti, Al, and Mo.…”

Section: Discussionmentioning

confidence: 93%

“…[7] Using the assumption that the silicide phase having negligible Cr concentration and all Cr is in solution with the b matrix (bulk concentration is 9 at. pct Cr), a rough estimate of Cr concentration in the b matrix subsequent to the precipitation of the Laves phase can be made.…”

Section: Discussionmentioning

confidence: 99%

“…It has been shown that Ti has a stronger phase separation tendency than Nb. [7] The tendency of phase separation is not as surprising in view of the fact that the b phase contains several elements in solution at high temperatures (T > 1573 K [7] ), and cooling from high temperature to lower temperature (T < 1473 K [7] ) may bring the system into the instability regime, leading to chemical separation. Apparently, the phase separation tendency is less pronounced in the high-temperature region and becomes enhanced upon cooling and aging at and below 1373 K. Furthermore, the b 1 and b 2 regions grow in dimension with time and evolve into distinct entities (marked A and B in Figure 8(a)), but in an The hexagonal pattern could be indexed best in terms of D8 8 and hexagonal structure, and not the D8 m orthorhombic phase.…”

Section: Discussionmentioning

confidence: 99%

“…(4) In alloy series 3, the formation of two types of silicide was noticed. Based on their chemical composition (Table III), both of these silicides could be assigned to be the 5:3-type silicide: [6,7] one richer in Nb and appearing in bright contrast in BSE ((Nb,Ti) 5 (Si,Al) 3 ) and the other richer in Ti and appearing in darker contrast in the BSE micrographs ((Ti,Nb) 5 (Si,Al) 3 ). In the case of Mo containing alloy (4A), in addition to the 5:3 silicide, the formation of (Nb,Ti,Mo) 3 (Si,Al)-type silicide (henceforth called 3:1 silicides) was also observed.…”

Section: A Microstructure Of As-cast Alloysmentioning

confidence: 99%

“…These fine precipitates were found to be rich in Cr and Ti. Because of the very small size of these precipitates, it was difficult to accurately ascertain their [7] with the Nb, Zr, and…”

Section: Aging Below 1373 Kmentioning

confidence: 99%

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Microstructural Evolution in Niobium-Based Alloys

Tewari

Song

Dey

et al. 2008

Metall Mater Trans A

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Nb-Ti-Cr-Si-Al-X alloys have been considered as candidate materials for high-temperature structural applications in aero engines. Using a multicomponent approach, attempts are being made to obtain good strength with adequate oxidation resistance at the expected operating temperatures (~1073 through 1273 K) in these alloys. In the microstructure of these alloys, which essentially consist of the silicide phase distributed in the bcc b matrix, the presence or absence of the Laves phase can bring about considerable changes in the mechanical properties. The present article reports on the instability observed in the b phase and also on the formation of the Laves phase in the b matrix. The extent of the chemical separation and elements responsible for this separation has been determined. Different morphologies of the Laves phase have been obtained by aging at different temperatures for various durations and the structure, chemistry, and volume fraction of these phases have been determined.

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: A Microstructure Of As-cast Alloysmentioning

confidence: 99%

“…These fine precipitates were found to be rich in Cr and Ti. Because of the very small size of these precipitates, it was difficult to accurately ascertain their [7] with the Nb, Zr, and…”

Section: Aging Below 1373 Kmentioning

confidence: 99%

See 3 more Smart Citations