Abstract
Supersaturated (Ti0.5 – xW0.5Crx)B2 (x = 0, 0.1, 0,2) solid solutions were produced by reaction sintering of transition metal diboride powders at a pressure of 60 MPa at 1800 °C. The formation kinetics of W2B5 precipitates were investigated at lower temperatures by X-ray diffractometry (XRD) and secondary electron microscopy (SEM). The precipitation rate constants as a function of reciprocal temperature show non-monotonic behaviour in the range between 1450 and 1700 °C with a maximum at about 1650 °C. At low temperatures, Arrhenius behaviour is approximately valid, where the precipitation kinetics are dominated by the diffusion of the transition metals. In contrast, at temperatures higher than 1650 °C, the precipitation rates decrease rapidly, since supersaturation, and consequently nucleation, is strongly reduced. The rate constants of precipitation are identical within error limits for Cr concentrations of x = 0.1 and x = 0.2, however, they are significantly lower for x = 0. This means that the addition of small amounts of Cr accelerates the precipitate formation, while further addition has no further influence. Samples resulting from powders which were high-energy milled with WC/Co hard balls before reaction sintering show an increased density of precipitated crystallites but no increased rate constants of precipitation. This result can be explained under the assumption that for these samples a significant amount of additional pre-existing nuclei was present before precipitation starts, which were formed by heterogeneous nucleation at Co impurities, introduced by the milling process.
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The authors would like to thank E. Ebeling for ceramographic preparation of the samples and for technical support and B. Mühlhan and S. Lenk for their assistance in SEM analysis. This work has been funded by the German Research Foundation (DFG).
References
[1] I. Mitra, R. Telle: J. Solid State Chem. 133 (1997) 25.10.1006/jssc.1997.7311Search in Google Scholar
[2] R. Telle, E. Fendler, E. Petzow: J. Hard Mater. 3 (1992) 211.Search in Google Scholar
[3] C. Schmalzried, R. Telle, B. Freitag, W. Mader: Z. Metallkd. 92 (2001) 1197.Search in Google Scholar
[4] E.R. Fotsing, H. Schmidt, G. Borchardt, C. Schmalzried, R. Telle: Phil. Mag. 36 (2005) 4409.10.1080/14786430500333323Search in Google Scholar
[5] H. Schmidt, G. Borchardt, C. Schmalzried, R. Telle, H. Baumann, S. Weber, H. Scherrer: J. Europ. Ceram. Soc. 23 (2003) 991.10.1016/S0955-2219(02)00231-5Search in Google Scholar
[6] H. Schmidt, G. Borchardt, C. Schmalzried, R. Telle, H. Baumann, S. Weber, H. Scherrer: J. Mater. Sci., in print.Search in Google Scholar
[7] M. Starink: J. Mater. Sci. 32 (1997) 4070.10.1023/A:1018649823542Search in Google Scholar
[8] M.T. Clavaguera-Mora, N. Clavaguera, D. Crespo, T. Pradnell: Prog. Mater. Sci. 47 (2002) 559.10.1016/S0079-6425(00)00021-9Search in Google Scholar
[9] J.W. Christian, in R.W. Cahn (Ed.), Physical Metallurgy, North Holland, Amsterdam (1965) 443.Search in Google Scholar
[10] M. Shibuya, T. Yoneda, T. Yamamoto, M. Ohyanagi, Z.A. Munir: J. Am. Ceram. Soc. 86 (2003) 354.10.1111/j.1151-2916.2003.tb00023.xSearch in Google Scholar
© 2006 Carl Hanser Verlag, München
Articles in the same Issue
- Frontmatter
- Microstructure and mechanical behavior of Pt-modified NiAl diffusion coatings
- Evolution of C-rich SiOC ceramics
- Evolution of C-rich SiOC ceramics
- Nanostructured SiC/BN/C ceramics derived from mixtures of B3N3H6 and [HSi(Me)C≡C]n
- Thermodynamic analysis of structural transformations induced by annealing of amorphous Si–C–N ceramics derived from polymer precursors
- Thermodynamic modelling of the Ce–Ni system
- Thermodynamic assessment of the Ce–O system in solid state from 60 to 67 mol.% O
- Phase transformations of iron nitrides at low temperatures (< 700 K) – application of mechanical mixtures of powders of nitrides and iron
- Effect of organic self-assembled monolayers on the deposition and adhesion of hydroxyapatite coatings on titanium
- Reconstruction and structural transition at metal/diamond interfaces
- Microstructure, hardness, and fracture toughness evolution of hot-pressed SiC/Si3N4 nano/micro composite after high-temperature treatment
- High-temperature plasticity of SiC sintered with Lu2O3-AlN additives
- Interaction of functionalised surfaces on silica with dissolved metal cations in aqueous solutions
- XRD and TEM study of NiO–LSGM reactivity
- Microstructure and dielectric properties of nanoscale oxide layers on sintered capacitor-grade niobium and V-doped niobium powder compacts
- Knudsen effusion mass spectrometric studies of the Al–Ni system: Thermodynamic properties over {AlNi + Al3Ni2} and {Al3Ni2 + Al3Ni}
- Aqueous solution deposition of indium hydroxide and indium oxide columnar type thin films
- Thermodynamic properties of B2-AlFeNi alloys: modelling of the B2-AlFe and B2-AlNi phases
- Kinetics of precipitate formation in (TixWyCrz)B2 solid solutions: influence of Cr concentration and Co impurities
- On the mechanisms governing the texture and microstructure evolution during static recrystallization and grain growth of low alloyed zirconium sheets (Zr702)
- Out-of-pile chemical compatibility of Pb–Bi eutectic alloy with Graphite
- Microstructural characterisation of a Co–Cr–Mo laser clad applied on railway wheels
- The Na–H system: from first-principles calculations to thermodynamic modeling
- Personal
- Conferences
- Frontmatter
- Basic
- Microstructure and mechanical behavior of Pt-modified NiAl diffusion coatings
- Evolution of C-rich SiOC ceramics
- Evolution of C-rich SiOC ceramics
- Nanostructured SiC/BN/C ceramics derived from mixtures of B3N3H6 and [HSi(Me)C≡C]n
- Thermodynamic analysis of structural transformations induced by annealing of amorphous Si–C–N ceramics derived from polymer precursors
- Thermodynamic modelling of the Ce–Ni system
- Thermodynamic assessment of the Ce–O system in solid state from 60 to 67 mol.% O
- Phase transformations of iron nitrides at low temperatures (< 700 K) – application of mechanical mixtures of powders of nitrides and iron
- Effect of organic self-assembled monolayers on the deposition and adhesion of hydroxyapatite coatings on titanium
- Reconstruction and structural transition at metal/diamond interfaces
- Applied
- Microstructure, hardness, and fracture toughness evolution of hot-pressed SiC/Si3N4 nano/micro composite after high-temperature treatment
- High-temperature plasticity of SiC sintered with Lu2O3-AlN additives
- Interaction of functionalised surfaces on silica with dissolved metal cations in aqueous solutions
- XRD and TEM study of NiO–LSGM reactivity
- Microstructure and dielectric properties of nanoscale oxide layers on sintered capacitor-grade niobium and V-doped niobium powder compacts
- Knudsen effusion mass spectrometric studies of the Al–Ni system: Thermodynamic properties over {AlNi + Al3Ni2} and {Al3Ni2 + Al3Ni}
- Aqueous solution deposition of indium hydroxide and indium oxide columnar type thin films
- Thermodynamic properties of B2-AlFeNi alloys: modelling of the B2-AlFe and B2-AlNi phases
- Regular Articles
- Kinetics of precipitate formation in (TixWyCrz)B2 solid solutions: influence of Cr concentration and Co impurities
- On the mechanisms governing the texture and microstructure evolution during static recrystallization and grain growth of low alloyed zirconium sheets (Zr702)
- Out-of-pile chemical compatibility of Pb–Bi eutectic alloy with Graphite
- Microstructural characterisation of a Co–Cr–Mo laser clad applied on railway wheels
- The Na–H system: from first-principles calculations to thermodynamic modeling
- Notifications
- Personal
- Conferences
Articles in the same Issue
- Frontmatter
- Microstructure and mechanical behavior of Pt-modified NiAl diffusion coatings
- Evolution of C-rich SiOC ceramics
- Evolution of C-rich SiOC ceramics
- Nanostructured SiC/BN/C ceramics derived from mixtures of B3N3H6 and [HSi(Me)C≡C]n
- Thermodynamic analysis of structural transformations induced by annealing of amorphous Si–C–N ceramics derived from polymer precursors
- Thermodynamic modelling of the Ce–Ni system
- Thermodynamic assessment of the Ce–O system in solid state from 60 to 67 mol.% O
- Phase transformations of iron nitrides at low temperatures (< 700 K) – application of mechanical mixtures of powders of nitrides and iron
- Effect of organic self-assembled monolayers on the deposition and adhesion of hydroxyapatite coatings on titanium
- Reconstruction and structural transition at metal/diamond interfaces
- Microstructure, hardness, and fracture toughness evolution of hot-pressed SiC/Si3N4 nano/micro composite after high-temperature treatment
- High-temperature plasticity of SiC sintered with Lu2O3-AlN additives
- Interaction of functionalised surfaces on silica with dissolved metal cations in aqueous solutions
- XRD and TEM study of NiO–LSGM reactivity
- Microstructure and dielectric properties of nanoscale oxide layers on sintered capacitor-grade niobium and V-doped niobium powder compacts
- Knudsen effusion mass spectrometric studies of the Al–Ni system: Thermodynamic properties over {AlNi + Al3Ni2} and {Al3Ni2 + Al3Ni}
- Aqueous solution deposition of indium hydroxide and indium oxide columnar type thin films
- Thermodynamic properties of B2-AlFeNi alloys: modelling of the B2-AlFe and B2-AlNi phases
- Kinetics of precipitate formation in (TixWyCrz)B2 solid solutions: influence of Cr concentration and Co impurities
- On the mechanisms governing the texture and microstructure evolution during static recrystallization and grain growth of low alloyed zirconium sheets (Zr702)
- Out-of-pile chemical compatibility of Pb–Bi eutectic alloy with Graphite
- Microstructural characterisation of a Co–Cr–Mo laser clad applied on railway wheels
- The Na–H system: from first-principles calculations to thermodynamic modeling
- Personal
- Conferences
- Frontmatter
- Basic
- Microstructure and mechanical behavior of Pt-modified NiAl diffusion coatings
- Evolution of C-rich SiOC ceramics
- Evolution of C-rich SiOC ceramics
- Nanostructured SiC/BN/C ceramics derived from mixtures of B3N3H6 and [HSi(Me)C≡C]n
- Thermodynamic analysis of structural transformations induced by annealing of amorphous Si–C–N ceramics derived from polymer precursors
- Thermodynamic modelling of the Ce–Ni system
- Thermodynamic assessment of the Ce–O system in solid state from 60 to 67 mol.% O
- Phase transformations of iron nitrides at low temperatures (< 700 K) – application of mechanical mixtures of powders of nitrides and iron
- Effect of organic self-assembled monolayers on the deposition and adhesion of hydroxyapatite coatings on titanium
- Reconstruction and structural transition at metal/diamond interfaces
- Applied
- Microstructure, hardness, and fracture toughness evolution of hot-pressed SiC/Si3N4 nano/micro composite after high-temperature treatment
- High-temperature plasticity of SiC sintered with Lu2O3-AlN additives
- Interaction of functionalised surfaces on silica with dissolved metal cations in aqueous solutions
- XRD and TEM study of NiO–LSGM reactivity
- Microstructure and dielectric properties of nanoscale oxide layers on sintered capacitor-grade niobium and V-doped niobium powder compacts
- Knudsen effusion mass spectrometric studies of the Al–Ni system: Thermodynamic properties over {AlNi + Al3Ni2} and {Al3Ni2 + Al3Ni}
- Aqueous solution deposition of indium hydroxide and indium oxide columnar type thin films
- Thermodynamic properties of B2-AlFeNi alloys: modelling of the B2-AlFe and B2-AlNi phases
- Regular Articles
- Kinetics of precipitate formation in (TixWyCrz)B2 solid solutions: influence of Cr concentration and Co impurities
- On the mechanisms governing the texture and microstructure evolution during static recrystallization and grain growth of low alloyed zirconium sheets (Zr702)
- Out-of-pile chemical compatibility of Pb–Bi eutectic alloy with Graphite
- Microstructural characterisation of a Co–Cr–Mo laser clad applied on railway wheels
- The Na–H system: from first-principles calculations to thermodynamic modeling
- Notifications
- Personal
- Conferences