Effect of Mo on microstructure and mechanical behaviour of as-cast Nbss–Nb5Si3 in situ composites

Chattopadhyay, Kausik; Balachandran, G.; Mitra, Rahul; Ray, K. K.

doi:10.1016/j.intermet.2006.01.054

Cited by 61 publications

(20 citation statements)

References 27 publications

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“…[15,35] The alloys A and B with Si content, slightly exceeding that at the eutectic point (17.5 at. pct Si) in the binary Nb-Si phase diagram [36] are hypereutectic.…”

Section: A Microstructural Constituentsmentioning

confidence: 98%

“…Table I shows the volume fractions of Nb ss and a-(Nb,Mo) 5 Si 3 determined by Rietveld analyses, [35] as well as the results of EDX analyses related to concentration of alloying elements present as substitutional solute in the Nb ss and a-(Nb,Mo) 5 Si 3 phases. [15,35] Because the oxidation resistance of the Nb ss and (Nb,Mo) 5 Si 3 phases are different, their volume fractions and compositions are important parameters in defining the oxidation behavior of the investigated alloys.…”

Section: A Microstructural Constituentsmentioning

confidence: 99%

“…The refractory Nb-Si-based alloys with high melting temperatures are of interest as candidate materials for aero-engine applications. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] The microstructure of the Nb-Si-based alloys consists of hard and brittle intermetallic Nb 5 Si 3 and relatively ductile Nb-solid solution (Nb ss ) phases. The Nb 5 Si 3 exhibits excellent high-temperature strength retention and creep resistance, [1] but poor ductility and fracture toughness.…”

Section: Introductionmentioning

confidence: 99%

“…[4] The resistance to cracking in these alloys (with microstructure showing a mixture of Nb ss and Nb 5 Si 3 ) is imparted by the ductile phase through intrinsic toughening mechanisms, such as crack arrest and bridging. [8,15] Therefore, an optimum volume fraction of Nb ss and Nb 5 Si 3 is required to achieve a desirable balance of mechanical properties involving room temperature fracture toughness, as well as hightemperature yield and creep strength, supplemented by appropriate oxidation resistance for high-temperature applications.…”

Section: Introductionmentioning

confidence: 99%

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Nonisothermal and Isothermal Oxidation Behavior of Nb-Si-Mo Alloys

Chattopadhyay

Mitra

Ray

2008

Metall Mater Trans A

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The nonisothermal and isothermal oxidation behavior of arc-melted, hypereutectic ternary alloys have been investigated vis-a`-vis that of Nb and Nb-10Si alloy. The nonisothermal studies carried out using simultaneous thermogravimetric and differential thermal analysis in the temperature range of 50°C to 1300°C using heating rates of 5°C, 15°C/min, 25°C/min, and 40°C/min have shown oxidation initiation at lower temperatures for slower heating rates and higher Mo content. Isothermal oxidation experiments have been carried out in dry air at 800°C, 1000°C, and 1150°C for 24 hours and the kinetics have been examined by the power-law equation. The studies show that the ternary Nb-Si-Mo alloys undergo less mass gain compared to the Nb and the Nb-10Si alloy. The hypo-or hypereutectic character of the alloys controls the oxidation behavior at 800°C, while the effect of Mo content is predominant at temperatures of 1000°C to 1150°C. X-ray diffraction and scanning electron microscopy (SEM) accompanied by energy dispersive X-ray analysis have shown that the oxide scales of all the alloys are made of Nb 2 O 5 and SiO 2 . The beneficial effect of alloying with Mo is attributed to the improved sinterability of the oxide scale and increase in the activity of Si, which assists in the formation of a stable and continuous layer of SiO 2 at the alloy-oxide interface.

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“…[15,35] The alloys A and B with Si content, slightly exceeding that at the eutectic point (17.5 at. pct Si) in the binary Nb-Si phase diagram [36] are hypereutectic.…”

Section: A Microstructural Constituentsmentioning

confidence: 98%

Section: A Microstructural Constituentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nonisothermal and Isothermal Oxidation Behavior of Nb-Si-Mo Alloys

Chattopadhyay

Mitra

Ray

2008

Metall Mater Trans A

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“…Recent research [5][6][7] has shown that the properties of Nb-Si alloys can be significantly improved by specific alloying elements. Alloying elements such as Ti, Cr, Al, Hf [8][9][10] , Mo [11][12][13] , Zr, Ta [14] and W [15] have been added to Nb-Si alloys at Si concentrations ranging from 12 at% to 22 at%.…”

Section: Introductionmentioning

confidence: 99%

Effects of Al addition on the microstructure and properties of Nb/Nb5Si3 in situ composites fabricated via spark plasma sintering

Long

Yao

2014

J. Wuhan Univ. Technol.-Mat. Sci. Edit.

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Dense Nb/Nb 5 Si 3 composites were fabricated via spark plasma sintering technology using Nb, Si, and Al elemental powders as raw materials. The microstructures of the synthesised composites were analyzed through scanning electron microscopy, X-ray diffraction, and electron probe microanalysis. The results show that the composites consisted of residual Nb particle phase and Nb 5 Si 3 phase. The microstructure of the Nb/ Nb 5 Si 3 in situ composites was evidently affected by Al addition, which prompted the formation of the Al 3 Nb 10 Si 3 phase. In addition, the Rockwell hardness of the composites decreased with the increase in Al additions. The Rockwell hardness of Nb-20Si is 60HRC, which decreased to approximately 52.7 HRC when the Al content increased to 15 at%. The oxidation resistance of the Nb/Nb 5 Si 3 in situ composites signifi cantly improved with the increase in Al addition.

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Silicides and Silicide Matrix Composites for High-Temperature Structural Applications

Mitra¹

2020

Handbook of Advanced Ceramics and Composites

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Effect of Mo on microstructure and mechanical behaviour of as-cast Nbss–Nb5Si3 in situ composites

Cited by 61 publications

References 27 publications

Nonisothermal and Isothermal Oxidation Behavior of Nb-Si-Mo Alloys

Nonisothermal and Isothermal Oxidation Behavior of Nb-Si-Mo Alloys

Effects of Al addition on the microstructure and properties of Nb/Nb5Si3 in situ composites fabricated via spark plasma sintering

Silicides and Silicide Matrix Composites for High-Temperature Structural Applications

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