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Transmission electron microscopy study of the microstructural evolution during high-temperature and low-stress (011) [11] shear creep deformation of the superalloy single crystal LEK 94

Published online by Cambridge University Press:  15 September 2017

Leonardo Agudo Jácome Open the ORCID record for Leonardo Agudo Jácome [Opens in a new window] ,
Gülcan Göbenli  and
Gunther Eggeler
Leonardo Agudo Jácome*
Affiliation:
Bundesanstalt für Materialforschung und -prüfung, Abteilung für Werkstofftechnik, Berlin 12205, Germany
Gülcan Göbenli
Affiliation:
Institut für Werkstoffe, Lehrstuhl Werkstoffwissenschaft, Ruhr-Universität Bochum, Bochum 44801, Germany
Gunther Eggeler
Affiliation:
Institut für Werkstoffe, Lehrstuhl Werkstoffwissenschaft, Ruhr-Universität Bochum, Bochum 44801, Germany
*
a) Address all correspondence to this author. e-mail: [email protected]
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Abstract

The present work describes the shear creep behavior of the superalloy LEK 94 at temperatures between 980 and 1050 °C and shear stresses between 50 and 140 MPa for loading on the macroscopic crystallographic shear system (MCSS) (011) $\left[ {01\bar 1} \right]$ . The strain rate versus strain curves show short primary and extended secondary creep regimes. We find an apparent activation energy for creep of Q app = 466 kJ/mol and a Norton-law stress exponent of n = 6. With scanning transmission electron microscopy, we characterize three material states that differ in temperature, applied stress, and accumulated strain/time. Rafting develops perpendicular to the maximum principal stress direction, γ channels fill with dislocations, superdislocations cut γ′ particles, and dislocation networks form at γ/γ′ interfaces. Our findings are in agreement with previous results for high-temperature and low-stress [001] and [110] tensile creep testing, and for shear creep testing of the superalloys CMSX-4 and CMSX-6 on the MCSSs (111) $\left[ {01\bar 1} \right]$ and (001)[100]. The parameters that characterize the evolving γ/γ′ microstructure and the evolving dislocation substructures depend on creep temperature, stress, strain, and time.

Keywords

dislocationsmicrostructurescanning transmission electron microscopy
Type
Articles
Information
Journal of Materials Research , Volume 32 , Issue 24: Focus Issue: Mechanical Properties and Microstructure of Advanced Metallic Alloys—in Honor of Prof. Haël Mughrabi PART B , 28 December 2017 , pp. 4491 - 4502
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Copyright © Materials Research Society 2017 

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Footnotes

b)

This author contributed equally to this work.

c)

This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs.org/editor-manuscripts/.

Contributing Editor: Mathias Göken

References

REFERENCES

Meetham, G.W.: The Development of Gas Turbine Materials (Applied Science Publishers, London, England, 1981); pp. 89–119.CrossRefGoogle Scholar
McLean, M.: Directionally Solidified Materials for High Temperature Service (The Metals Society, London, England, 1983); pp. 5–8.Google Scholar
Sims, C.T.: A history of superalloy metallurgy for superalloy metallurgists. In Superalloys 1984, Gell, M., ed. (Metallurgical Society AIME Proceedings, Champion, PA, 1984); p. 399.Google Scholar
Durand-Charre, M.: The Microstructure of Superalloys (Gordon & Breach, London, England, 2003); pp. 6, 57, 92.Google Scholar
Reed, R.C.: The Superalloys—Fundamentals and Applications (Cambridge University Press, Cambridge, England, 2006); pp. 4, 16, 19, 121.Google Scholar
Bürgel, R., Maier, H.J., and Niendorf, T.: Handbuch Hochtemperatur-Werkstofftechnik, 4th ed. (Vieweg and Teubner, Wiesbaden, Germany, 2011); pp. 107–114.CrossRefGoogle Scholar
Garofalo, F.: Fundamentals of Creep and Creep-Rupture in Metals (Macmillan, New York, USA, 1965); pp. 46–101.Google Scholar
Ilschner, B.: Hochtemperatur-Plastizität (Springer, Berlin, Germany, 1973); pp. 26–30.Google Scholar
Evans, R.W. and Wilshire, B.: Creep of Metals and Alloys (Institute of Materials, London, England, 1985); pp. 10–14.Google Scholar
Cadek, J.: Creep in Metallic Materials (Elsevier, Amsterdam, Netherlands, 1988); pp. 44–64.Google Scholar
Nabarro, F.R.N. and de Villiers, H.L.: The Physics of Creep (Taylor and Francis, London, England, 1995); pp. 25–34.Google Scholar
Kassner, M.E.: Fundamentals of Creep in Metals and Alloys (Elsevier, Amsterdam, Netherlands, 2009); pp. 15, 21, 74.Google Scholar
Pollock, T.M. and Argon, A.S.: Creep resistance of CMSX-3 nickel-base superalloy single-crystals. Acta Metall. Mater. 40, 1 (1992).CrossRefGoogle Scholar
Keller, R.R., Maier, H.J., and Mughrabi, H.: Characterization of interfacial dislocation networks in a creep-deformed nickel-base superalloy. Scr. Metall. Mater. 28, 23 (1993).CrossRefGoogle Scholar
Matan, N., Cox, D.C., Rae, C.M.F., and Reed, R.C.: On the kinetics of rafting in CMSX-4 superalloy single crystals. Acta Mater. 47, 2031 (1999).Google Scholar
Acharya, M.V. and Fuchs, G.E.: The effect of long-term thermal exposures on the microstructure and properties of CMSX-10 single crystal Ni-base superalloys. Mater. Sci. Eng., A 381, 143 (2004).CrossRefGoogle Scholar
Caron, P., Ramusat, C., and Diologent, F.: Influence of the γ0 fraction on the γ/γ′ topological inversion during high temperature creep of single crystal superalloys. In Superalloys 2008, Reed, R.C., Green, K.A., Caron, P., Gabb, T.P., Fahrmann, M.G., Huron, E.S., and Woodard, S.A., eds. (The Minerals, Metals and Materials Society, Champion, USA, 2008); p. 159.Google Scholar
Dirand, L., Cormier, J., Jacques, A., Chateau-Cornu, J-P., Schenk, T., Ferry, O., and Bastie, P.: Measurement of the effective γ/γ′ lattice mismatch during high temperature creep of Ni-based single crystal superalloy. Mater. Charact. 77, 32 (2013).CrossRefGoogle Scholar
Bardet, J.P.: Experimental Soil Mechanics (Prentice Hall, London, England, 1997); pp. 430–443.Google Scholar
Anderson, P.M., Hirth, J.P., and Lothe, J.: Theory of Dislocations, 3nd ed. (Cambridge University Press, Cambridge, England, 2016); p. 637.Google Scholar
Dieter, G.E.: Mechanical Metallurgy, 3rd ed. (McGraw-Hill, London, England, 1988); pp. 15, 41, 77, 79, 139.Google Scholar
Mayr, C., Eggeler, G., and Dlouhy, A.: Double shear creep deformation of superalloy single crystals. In Strength of Materials: Fundamental Physical Aspects of the Strength of Crystalline Materials ICSMA10, Oikawa, H., Maruyama, K., Takeuchi, S., and Yamaguchi, M., eds. (Japan Institute of Metals Proceedings, Sendai, Japan, 1994); p. 709.Google Scholar
Mayr, C., Eggeler, G., Webster, G.A., and Peter, G.: Double shear creep testing of superalloy single crystals at temperatures above 1000 °C. Mater. Sci. Eng., A 199, 121 (1995).CrossRefGoogle Scholar
Peter, G., Probst-Hein, M., Kolbe, M., Neuking, K., and Eggeler, G.: Finite element stress and strain analysis of a double shear creep specimen. Materialwiss. Werkstofftech. 28, 457 (1997).CrossRefGoogle Scholar
Mayr, C., Eggeler, G., and Dlouhy, A.: Analysis of dislocation structures after double shear creep deformation of CMSX6-superalloy single crystals at temperatures above 1000 °C. Mater. Sci. Eng., A 207, 51 (1996).Google Scholar
Kolbe, M., Dlouhy, A., and Eggeler, G.: Dislocation reactions at γ/γ′-interfaces during shear creep deformation in the macroscopic crystallographic shear system (001)[110] of CMSX6 superalloy single crystals at 1025 °C. Mater. Sci. Eng., A 246, 133 (1998).CrossRefGoogle Scholar
Eggeler, G. and Dlouhy, A.: On the formation of 〈010〉-dislocations in the γ′-phase of superalloy single crystals during high temperature low stress creep. Acta Mater. 45, 4251 (1997).CrossRefGoogle Scholar
Kamaraj, M., Mayr, C., Kolbe, M., and Eggeler, G.: On the influence of stress state on rafting in the single crystal superalloy CMSX-6 under conditions of high temperature and low stress creep. Scr. Mater. 38, 589 (1998).CrossRefGoogle Scholar
Serin, K., Göbenli, G., and Eggeler, G.: On the influence of stress state, stress level and temperature on γ-channel widening in the single crystal superalloy CMSX-4. Mater. Sci. Eng., A 387–389, 133 (2004).CrossRefGoogle Scholar
Kamaraj, M., Serin, K., Kolbe, M., Neuking, K., and Eggeler, G.: Shear creep deformation of the super alloy single crystal CMSX-4 at high temperatures and low stresses. Materialwiss. Werkstofftech. 34, 469 (2003).Google Scholar
Glatzel, U., Mack, T., Wöllmer, S., and Wortmann, J.: Nickel base alloy for casting single crystal components. European Patent No. EP 1 223 229 B1, 2006.Google Scholar
Wöllmer, S., Mack, T., and Glatzel, U.: Influence of tungsten and rhenium concentration on creep properties of a second generation superalloy. Mater. Sci. Eng., A 319–321, 792 (2001).CrossRefGoogle Scholar
Mälzer, G., Hayes, R.W., Mack, T., and Eggeler, G.: Miniature specimen assessment of creep of the single-crystal superalloy LEK 94 in the 1000 °C temperature range. Metall. Mater. Trans. A 38, 314 (2007).Google Scholar
Nörtershäuser, P., Frenzel, J., Ludwig, A., Neuking, K., and Eggeler, G.: The effect of cast microstructure and crystallography on rafting, dislocation plasticity and creep anisotropy of single crystal Ni-base superalloys. Mater. Sci. Eng., A 626, 305 (2015).CrossRefGoogle Scholar
Agudo Jácome, L., Eggeler, G., and Dlouhý, A.: Advanced scanning transmission stereo electron microscopy of structural and functional engineering materials. Ultramicroscopy 122, 48 (2012).CrossRefGoogle ScholarPubMed
Agudo Jácome, L., Nörtershäuser, P., Heyer, J.K., Lahni, A., Frenzel, J., Dlouhý, A., Somsen, C., and Eggeler, G.: High-temperature and low-stress creep anisotropy of single-crystal superalloys. Acta Mater. 61, 2926 (2013).CrossRefGoogle Scholar
Agudo Jácome, L., Nörtershäuser, P., Somsen, C., Dlouhý, A., and Eggeler, G.: On the nature of γ′ phase cutting and its effect on high temperature and low stress creep anisotropy of Ni-base single crystal superalloys. Acta Mater. 69, 246 (2014).CrossRefGoogle Scholar
Serin, K.: Werkstoffwissenschaftliche Untersuchungen zum mechanischen Verhalten und zur Gefügestabilität der einkristallinen Superlegierung CMSX-4. Dr.-Ing. thesis, Ruhr-Universität Bochum, Germany, 2002, p. 104.Google Scholar
Göbenli, G.: Werkstoffwissenschaftliche Untersuchungen zum ein- und mehrachsigen Kriechverhalten der Nickelbasis-Superlegierungen CMSX-4 und LEK 94 oberhalb 1000 °C. Dr.-Ing. thesis, Ruhr-Universität Bochum, 2005, p. 101.Google Scholar
Serin, K., Neuser, R.D., Eggeler, G., Kamaraj, M., Kolbe, M., and Heitmaier, M.: Eine quantitative metallographische Studie zur Floßbildung und zur Kanalverbreiterung beim Kriechen einkristalliner Superlegierungen. Prakt. Metallogr. 38, 680 (2001).CrossRefGoogle Scholar
Larson, F.R. and Miller, J.: A time-temperature relationship for rupture and creep stresses. Trans. ASME 74, 765 (1952).Google Scholar
Epishin, A., Link, T., Portella, P.D., and Brückner, U.: Evolution of the γ/γ′ microstructure during high-temperature creep of a nickel-base superalloy. Acta Mater. 48, 4169 (2000).CrossRefGoogle Scholar
Wollgramm, P., Bürger, D., Parsa, A.B., Neuking, K., and Eggeler, G.: The effect of stress, temperature and loading direction on the creep behavior of Ni-base single crystal superalloy miniature creep specimens. Mater. High Temp. 33, 346 (2016).Google Scholar
Wollgram, P., Buck, H., Neuking, K., Parsa, A.B., Schuwalow, S., Rogal, J., Drautz, R., and Eggeler, G.: On the role of Re in the stress and temperature dependence of creep of Ni-base single crystal superalloys. Mater. Sci. Eng., A 628, 382 (2015).CrossRefGoogle Scholar
Eggeler, G. and Blum, W.: Coarsening of dislocation structure after stress reduction during creep of NaCl single crystals. Philos. Mag. A 44, 12065 (1981).Google Scholar
Blum, W.: High temperature deformation and creep of crystalline solids. In Plastic Deformation and Fracture of Materials, Mughrabi, H., ed. (Wiley VCH, Weinheim, Germany, 1993); pp. 359–405.Google Scholar