Abstract
The diffusion in iridium-rich Ir-Nb alloys has been studied by single-phase interdiffusion experiments. The chemical diffusion coefficient has been measured for the primary fcc solid-solution and theL12 ordered compound Ir3Nb in the temperature range between 1650 and 1950 °C, using Ir/Ir-8Nb and Ir-26Nb/Ir-28Nb diffusion couples, respectively (numbers indicate mol%). While the chemical diffusion coefficient in the solid-solution phase is close to the tracer self-diffusion coefficient of pure iridium, the diffusion in the compound phase is extremely slow: the chemical diffusion coefficient is 1/40 to 1/50 of that in the solid solution. The low diffusion rate in the compound must be beneficial for high-temperature performance of refractory superalloys based on the Ir-Nb system.
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References
Y. Yamabe-Mitarai, Y. Gu, C. Huang, R. Völkl, and H. Harada, Platinum-Group-Metal-Based Intermetallics as High-Temperature Structural Materials,JOM, 2004,56(9), p 34–39
Y. Yamabe-Mitarai, Y. Ro, T. Maruko, and H. Harada, Ir-Base Refractory Superalloys for Ultra-High Temperatures,Metall. Mater. Trans. A, 1998,29A(2), p 537–549
Y. Yamabe-Mitarai, Y. Gu, and H. Harada, Compressive Strength and Creep Properties of Ir-Nb-Zr Alloys between 1473 and 2073 K,Metall. Mater. Trans. A, 2003,34A(10), p 2207–2215
M. Uchida, H. Numakura, Y. Yamabe-Mitarai, and E. Bannai, Chemical Diffusion in Ir3Nb,Scr. Mater., 2005,52(1), p 11–15
J.I. Goldstein, D.E. Newbury, P. Echlin, D.C. Joy, A.D. Romig Jr., and C.E. Lyman, C. Fiori, and E. Lifshin,Scanning Electron Microscopy and X-ray Microanalysis, 2nd ed., Plenum Press, 1992, Chap. 8
H. Mehrer, Diffusion in Intermetallics,Mater. Trans., JIM, 1996,37(6), p 1259–1280
H. Mehrer, N. Stolica, and N.A. Stolwijk, Self-Diffusion in Solid Metallic Elements,Diffusion in Solid Metals and Alloys, H. Mehrer, Ed., Landolt-Börnstein New Series, Group III, Vol 26, Springer Verlag, Berlin, 1990, Chap. 2
A.M. Brown and M.F. Ashby, Correlations for Diffusion Constants,Acta Metall., 1980,28(8), p 1085–1101
L.S. Darken, Diffusion, Mobility and Their Interrelation through Free Energy in Binary Metallic Systems,Trans. AIME, 1948,175(1), p 184–194
J.R. Manning, Diffusion and the Kirkendall Shift in Binary Alloys,Acta Metall., 1967,15(5), p 817–826
I.A. Belova and G.E. Murch, Test of the Validity of the Darken/Manning Relation for Diffusion in Ordered Alloys Taking the Ll2 Structure,Philos. Mag. A, 1998,78(5), p 1085–1092
T. Ikeda, A. Almazouzi, H. Numakura, M. Koiwa, W. Sprengel, and H. Nakajima, Single-Phase Interdiffusion in Ni3Al,Acta Mater., 1998,46(15), p 5369–5376
T. Abe, Y. Chen, Y. Yamabe-Mitarai, and H. Numakura, in preparation
Y.A. Chang and J.P. Neumann, Thermodynamics and Defect Structure of Intermetallic Phases with the B2 (CsCl) Structure,Prog. Solid State Chem., 1982,14(4), p 221–301
T. Ikeda, H. Numakura, and M. Koiwa, A Bragg-Williams Model for the Thermodynamic Activity and the Thermodynamic Factor in Diffusion for Ordered Alloys with Substitutional Defects,Acta Mater., 1998,46(18), p 6605–6613;idems, corrigendum,Acta Mater., 1999,47(6), p 1993
M. Watabane, Z. Horita, T. Sano, and M. Nemoto, Electron Microscopy Study of Ni/Ni3Al Diffusion-Couple Interface—II. Diffusivity Measurement,Acta Metall. Mater., 1994,42(10), p 3389–3396
H. Numakura, T. Ikeda, M. Koiwa, and A. Almazouzi, Self-Diffusion Mechanism in Ni-Based Ll2 Type Intermetallic Compounds,Philos. Mag. A, 1998,77(4), p 887–909
H. Numakura, T. Ikeda, H. Nakajima, and M. Koiwa, Diffusion in Ni3Al, Ni3Ga and Ni3Ge,Mater. Sci. Eng. A, 2001,312(1–2), p 109–117
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Numakura, H., Watanabe, T., Uchida, M. et al. Chemical diffusion in the iridium-richA1 andL12 phases in the Ir-Nb system. JPED 27, 638–643 (2006). https://doi.org/10.1007/BF02736566
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DOI: https://doi.org/10.1007/BF02736566