Microstructure evolution and room temperature fracture toughness of an integrally directionally solidified Nb–Ti–Si based ultrahigh temperature alloy

Guo, Hao; Guo, Xiping

doi:10.1016/j.scriptamat.2010.12.008

Cited by 115 publications

(27 citation statements)

References 13 publications

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“…The following factors are toughing contributors for Nb-silicide based in situ composites: intrinsic toughness of the intermetallics phase (a-Nb 5 Si 3 , b-Nb 5 Si 3 , g-Nb 5 Si 3 , C-14 NbCr 2 and C-15 NbCr 2 ) [2,4,5], the scale or morphology of the toughening phase, the Fig. 4 (a) shows BSE image of the F2 alloy, the addition of 4.5B promotes the (Nb) þ T2 eutectic, (Nb) (bright) and T2 (dark) grows simultaneously from the liquid.…”

Section: Resultsmentioning

confidence: 99%

“…NbCr 2 ) were obtained by traditional trial-and-error alloying design [2e5], and some of them are generally needed to avoid in the microstructure, like hexagonal g-Nb 5 Si 3 with high anisotropy of coefficients of thermal expansion (CTE) and prone to forming microcracks [5]. a-Nb 5 Si 3 (to be referred as T2 afterwards) is desirable intermetallic phase due to its higher thermodynamic stability and balanced properties [3,6].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of B and Si on the fracture toughness of the Nb–Si alloys

Sun¹,

Guo²,

Tian³

et al. 2014

Intermetallics

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of B and Si on the fracture toughness of the Nb–Si alloys

Sun¹,

Guo²,

Tian³

et al. 2014

Intermetallics

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“…Then its room temperature fracture toughness was as high as 17?5-23?8 MPa m 1/2 . 16 However, few reports about the effect of the integrally directional solidification on the microstructure of multicomponent and multiphase Nb-Ti-Cr-Si based alloys can be found in open literatures.…”

Section: Introductionmentioning

confidence: 99%

Microstructure of Nb–Ti–Cr–Si based ultrahigh temperature alloy processed by integrally directional solidification

Guo

2015

Materials Science and Technology

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The Nb-Ti-Cr-Si based ultrahigh temperature alloy was integrally directionally solidified with the using of special ceramic crucibles. The effects of different withdrawing rates on the microstructure and the solidification path in a Nb-Ti-Cr-Si based ultrahigh temperature alloy were investigated. The results showed that the microstructure was composed of primary niobium solid solution (Nbss) dendrites, Nbss/(Nb,X) 5 Si 3 (here X represents Ti and Hf elements) eutectic colonies and fine Ti rich phase layer between Nbss dendrites and Nbss/(Nb,X) 5 Si 3 eutectic colonies when the withdrawal rates vary from 2?5 to 10 mm s 21 . However, the directionally solidified microstructures were composed of primary Nbss dendrites, Nbss/(Nb,X) 5 Si 3 eutectic colonies and finer (Ti,Nb)ss/Nb 3 Si/Cr 2 Nb colonies colonies when the withdrawal rate was reached and exceed than 20 mm s 21 . The primary Nbss and Nbss/(Nb,X) 5 Si 3 eutectic aligned the growth direction when the withdrawal rates vary from 2?5 to 20 mm s 21 ; however, the discontinuous (Nb,X) 5 Si 3 plates were present when the withdrawal rates vary from 50 to 100 mm s 21 . The solidification path was studied according to the microstructure of solid/liquid interface.

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“…On the other hand, directional solidification is a promising technique for getting well aligned multiphase structures, resulting in enchancing both high and room temperature mechanical propertites of Nb-Si based alloys [9,10]. And the microstructure could be controlled by the directional solidification parameters such as temperature gradient and growth rate [11].…”

Section: Introductionmentioning

confidence: 99%

Microstructure Evolution in Nb-12Si-22Ti-14Cr-2Al2Hf Alloy Fabricated by Directional Solidification

Yuan

Zhang

et al. 2014

High Temperature Materials and Processes

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In this work, the microstructure evolution of the Nb-12Si-22Ti-14Cr-2Al-2Hf alloy (at.%) fabricated by liquidmetal-cooled directional solidification (LMC) was investigated and the solidification behaviors were discussed. The results revealed that the growth rate was of crucial in controlling the microstructure of this alloy and the higher growth rate was beneficial to the formation of metastable phase Nb 3 Si. The microstructure of non-melted region consisted of Nb SS dendrites, Nb SS /Nb 5 Si 3 eutectics and Ti-rich Nb SS /Cr 2 Nb eutectics while the microstructure of quasi-steady-state growth region of this alloy consisted of Nb SS dendrites, Nb 3 Si laths and Ti-rich Nb SS /Cr 2 Nb eutectic. Nb 3 Si had the advantage of nucleation at medium/ high growth rate. Therefore, the microstructure evolution occurred in this study was owing to the increase of growth rate.

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Microstructure evolution and room temperature fracture toughness of an integrally directionally solidified Nb–Ti–Si based ultrahigh temperature alloy

Cited by 115 publications

References 13 publications

Effects of B and Si on the fracture toughness of the Nb–Si alloys

Effects of B and Si on the fracture toughness of the Nb–Si alloys

Microstructure of Nb–Ti–Cr–Si based ultrahigh temperature alloy processed by integrally directional solidification

Microstructure Evolution in Nb-12Si-22Ti-14Cr-2Al2Hf Alloy Fabricated by Directional Solidification

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