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Phase relations in the Nb-Ni-Cr system at 1,100 °C.

Kodentsov AA, van Loo FJ - Monatsh. Chem. (2012)

Bottom Line: It was found that nearly 28 at.% of Cr can be dissolved in the μ phase (Nb7Ni6) at this temperature, and the solubility of chromium in NbNi3 is approximately 5 at.%.The presence of this pseudo-ternary compound which is in equilibrium with all binary intermetallics and body-centred cubic (BCC) Nb- and Cr-based solid solutions largely determines the topology of the isotherm at 1,100 °C.The formation of this phase was also observed in the reaction zone between Nb and Ni-Cr solid solution when chromium concentration exceeded 15 at.%.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Materials and Interface Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.

ABSTRACT

Abstract: The isothermal cross section through the ternary phase diagram Nb-Ni-Cr at 1,100 °C was constructed by means of diffusion couples and equilibrated alloys. It was found that nearly 28 at.% of Cr can be dissolved in the μ phase (Nb7Ni6) at this temperature, and the solubility of chromium in NbNi3 is approximately 5 at.%. Under these circumstances the low-temperature (cubic) modification of the NbCr2 Laves phase can dissolve up to 6 at.% of nickel, but further increase of the Ni content (up to approximately 10 at.%) stabilizes the hexagonal (high-temperature) modification of the Laves phase. The presence of this pseudo-ternary compound which is in equilibrium with all binary intermetallics and body-centred cubic (BCC) Nb- and Cr-based solid solutions largely determines the topology of the isotherm at 1,100 °C. The formation of this phase was also observed in the reaction zone between Nb and Ni-Cr solid solution when chromium concentration exceeded 15 at.%.

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Microstructure of the three-phase alloys of the Nb–Ni–Cr system after equilibrating at 1,100 °C in vacuum for 196 h and quenching a Ni50Cr40Nb10, b Ni40Cr40Nb20, c Ni55Cr5Nb40, and d Ni15Cr35Nb50 (the various phases on the micrographs are denoted by their binary formulae. T is the pseudo-ternary phase, and Niss, Crss, and Nbss are the Ni-, Cr-, and Nb-based solid solution, respectively)
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Fig3: Microstructure of the three-phase alloys of the Nb–Ni–Cr system after equilibrating at 1,100 °C in vacuum for 196 h and quenching a Ni50Cr40Nb10, b Ni40Cr40Nb20, c Ni55Cr5Nb40, and d Ni15Cr35Nb50 (the various phases on the micrographs are denoted by their binary formulae. T is the pseudo-ternary phase, and Niss, Crss, and Nbss are the Ni-, Cr-, and Nb-based solid solution, respectively)

Mentions: As it was expected, after equilibrating at 1,100 °C for 400 h and quenching ternary alloys with nominal composition Ni50Cr40Nb10, Ni40Cr40Nb20, Ni55Cr5Nb40, and Ni15Cr35Nb50, they indeed exhibited a three-phase morphology (Fig. 3). The composition of the phases present in the alloys after heat treatment was measured with electron probe microanalysis (EPMA) and the corresponding three-phase equilibria were plotted on the isotherm. It was found that nearly 28 at.% of Cr can be dissolved in the μ phase (Nb7Ni6) at this temperature, and the solubility of chromium in the NbNi3 is approximately 5 at.%.Fig. 3


Phase relations in the Nb-Ni-Cr system at 1,100 °C.

Kodentsov AA, van Loo FJ - Monatsh. Chem. (2012)

Microstructure of the three-phase alloys of the Nb–Ni–Cr system after equilibrating at 1,100 °C in vacuum for 196 h and quenching a Ni50Cr40Nb10, b Ni40Cr40Nb20, c Ni55Cr5Nb40, and d Ni15Cr35Nb50 (the various phases on the micrographs are denoted by their binary formulae. T is the pseudo-ternary phase, and Niss, Crss, and Nbss are the Ni-, Cr-, and Nb-based solid solution, respectively)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4494769&req=5

Fig3: Microstructure of the three-phase alloys of the Nb–Ni–Cr system after equilibrating at 1,100 °C in vacuum for 196 h and quenching a Ni50Cr40Nb10, b Ni40Cr40Nb20, c Ni55Cr5Nb40, and d Ni15Cr35Nb50 (the various phases on the micrographs are denoted by their binary formulae. T is the pseudo-ternary phase, and Niss, Crss, and Nbss are the Ni-, Cr-, and Nb-based solid solution, respectively)
Mentions: As it was expected, after equilibrating at 1,100 °C for 400 h and quenching ternary alloys with nominal composition Ni50Cr40Nb10, Ni40Cr40Nb20, Ni55Cr5Nb40, and Ni15Cr35Nb50, they indeed exhibited a three-phase morphology (Fig. 3). The composition of the phases present in the alloys after heat treatment was measured with electron probe microanalysis (EPMA) and the corresponding three-phase equilibria were plotted on the isotherm. It was found that nearly 28 at.% of Cr can be dissolved in the μ phase (Nb7Ni6) at this temperature, and the solubility of chromium in the NbNi3 is approximately 5 at.%.Fig. 3

Bottom Line: It was found that nearly 28 at.% of Cr can be dissolved in the μ phase (Nb7Ni6) at this temperature, and the solubility of chromium in NbNi3 is approximately 5 at.%.The presence of this pseudo-ternary compound which is in equilibrium with all binary intermetallics and body-centred cubic (BCC) Nb- and Cr-based solid solutions largely determines the topology of the isotherm at 1,100 °C.The formation of this phase was also observed in the reaction zone between Nb and Ni-Cr solid solution when chromium concentration exceeded 15 at.%.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Materials and Interface Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.

ABSTRACT

Abstract: The isothermal cross section through the ternary phase diagram Nb-Ni-Cr at 1,100 °C was constructed by means of diffusion couples and equilibrated alloys. It was found that nearly 28 at.% of Cr can be dissolved in the μ phase (Nb7Ni6) at this temperature, and the solubility of chromium in NbNi3 is approximately 5 at.%. Under these circumstances the low-temperature (cubic) modification of the NbCr2 Laves phase can dissolve up to 6 at.% of nickel, but further increase of the Ni content (up to approximately 10 at.%) stabilizes the hexagonal (high-temperature) modification of the Laves phase. The presence of this pseudo-ternary compound which is in equilibrium with all binary intermetallics and body-centred cubic (BCC) Nb- and Cr-based solid solutions largely determines the topology of the isotherm at 1,100 °C. The formation of this phase was also observed in the reaction zone between Nb and Ni-Cr solid solution when chromium concentration exceeded 15 at.%.

No MeSH data available.


Related in: MedlinePlus