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Use of spherical indentation technique for measurement of property variations of γTiAl

Published online by Cambridge University Press:  24 November 2011

Alfred Cornec ,
Mohammad Rizviul Kabir  and
Norbert Huber
Alfred Cornec*
Affiliation:
Division of Materials Mechanics, Institute of Materials Research, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
Mohammad Rizviul Kabir
Affiliation:
Institute of Materials Research, German Aerospace Center (DLR), 51147 Köln, Germany
Norbert Huber
Affiliation:
Division of Materials Mechanics, Institute of Materials Research, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
*
a)Address all correspondence to this author. e-mail: alfred.cornec@hzg.de
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Abstract

Novel lightweight intermetallic titanium aluminides, so-called γTiAl, provide good strength and creep resistance up to 700 °C. Their stress–strain behavior at room temperature is however strongly confined in elongation due to their low ductility. For studying the stress–strain behavior of γTiAl, the viscoplastic mechanical properties are determined using spherical indentation testing. The identification problem is solved on the continuum level by neural network analysis, which is based on a unified viscoplasticity model. The identified material parameters are validated by comparing the predicted stress–strain behavior with conventional compression tests at different deformation velocities. It was found that the average response of the indentation tests is in good agreement with the compression tests of round bars. Using a spherical indenter tip of R = 0.2 mm, a small volume is tested, offering possibilities for investigation of local property variations due to processing. The experimental indentation curves exhibited wide hysteresis loops, revealing the existence of pure kinematic hardening. Since tensile fracture strength for γTiAl is very low, microcracking occurred during loading as well as during unloading, significantly contributing to the unloading compliance.

Keywords

Stress/strain relationshipMicrostructureSimulation
Type
Articles
Information
Journal of Materials Research , Volume 27 , Issue 1: Focus Issue: Instrumented Indentation , 14 January 2012 , pp. 378 - 388
Copyright
Copyright © Materials Research Society 2011

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References

REFERENCES

1.Appel, F. and Wagner, R.: Microstructure and deformation of two-phase titanium aluminides. Mater. Sci. Eng., R 22, 187 (1998).CrossRefGoogle Scholar
2.Lorenz, U., Appel, F., and Wagner, R.: Dislocation dynamics and fracture processes in two-phase titanium aluminide alloys. Mater. Sci. Eng., A 234–236, 846 (1997).CrossRefGoogle Scholar
3.Chan, K.S., Wang, P., Bhate, N., and Kumar, K.S.: Intrinsic and extrinsic fracture resistance in lamellar TiAl alloys. Acta Mater. 52, 4601 (2004).CrossRefGoogle Scholar
4.Huang, Z.W., Bowen, P., Davey, S., and Blenkinsop, P.A.: Crystallographic features of intralamellar fracture in a fully lamellar TiAl Based alloy. Scr. Mater. 38, 1117 (1998).Google Scholar
5.Lu, Y.H., Zhang, Y.G., Qiao, L.J., Wang, Y.B., Chen, C.Q., and Chu, W.Y.: The fracture mechanism of fully lamellar γTiAl alloy through in-situ SEM observation. Intermetallics 8, 1443 (2000).CrossRefGoogle Scholar
6.Maruyama, K., Yamada, N., and Sato, H.: Effects of lamellar spacing on mechanical properties of fully lamellar Ti-39.4mol%Al alloy. Mater. Sci. Eng. A 319–321, 360 (2001).CrossRefGoogle Scholar
7.Arata, J.J.M., Kumar, K.S., Curtin, W.A., and Needleman, A.: Crack growth in lamellar titanium aluminide. Int. J. Fract. 111, 163 (2001).Google Scholar
8.Roos, A., Chaboche, J-L., Gélébart, L., and Crepin, J.: Multiscale modeling of titanium aluminides. Int. J. Plast. 20, 811 (2004).Google Scholar
9.Werwer, M. and Cornec, A.: Numerical simulation of plastic deformation and fracture in PST crystals of TiAl. Comput. Mater. Sci. 19, 97 (2000).CrossRefGoogle Scholar
10.Grujicic, M. and Zhang, Y.: Crystal plasticity analysis of the effect of dispersed β-phase on deformation and fracture of lamellar γ+α2 titan aluminide. Mater. Sci. Eng., A 265, 285 (1999).CrossRefGoogle Scholar
11.Dimiduk, D.M., Parthansarathy, T.A., and Hassledline, P.M.: Design-tool representations of strain compatibility and stress-strain relationships for lamellar gamma titanium aluminides. Intermetallics 9, 875 (2001).CrossRefGoogle Scholar
12.Lapin, J.: Effect of lamellar structure on micro hardness and yield stress of directionally solidified intermetallic Ti-46Al-2W-05Si alloy. J. Mater. Sci. Lett. 22, 747 (2003).CrossRefGoogle Scholar
13.Dorner, D., Röller, K., Skrotzki, B., Stöckhert, B., and Eggeler, G.: Creep of a TiAl alloy: A comparison of indentation and tensile testing. Mater. Sci. Eng., A 357, 346 (2003).Google Scholar
14.Zambaldi, C. and Raabe, D.: Plastic anisotropy of γ-TiAl revealed by axisymmetric indentation. Acta Mater. 58, 3516 (2010).CrossRefGoogle Scholar
15.Huber, N. and Tsakmakis, C.: A new loading history for identification of viscoplastic properties by spherical indentation. J. Mater. Res. 19, 101 (2004).CrossRefGoogle Scholar
16.Tyulyukovskiy, E. and Huber, N.: Identification of viscoplastic material parameters from spherical indentation data: Part I. Neural networks. J. Mater. Res. 21, 664 (2006).CrossRefGoogle Scholar
17.Klötzer, D., Ullner, C., Tyulyukovskiy, E., and Huber, N.: Identification of viscoplastic material parameters from spherical indentation data: Part II. Experimental validation of the method. J. Mater. Res. 21, 677 (2006).CrossRefGoogle Scholar
18.Tyulyukovskiy, E. and Huber, N.: Neural networks for tip correction of spherical indentation curves from bulk metals and thin films. J. Mech. Phys. Solids 55, 391 (2007).CrossRefGoogle Scholar
19.Huber, N., Tyulyukovskiy, E., Schneider, H-C., Rolli, R., and Weick, M.: An indentation system for determination of viscoplastic stress-strain behavior of small metal volumes before and after irradiation. J. Nucl. Mater. 377, 352 (2008).CrossRefGoogle Scholar
20.Heerens, J., Mubarok, F., and Huber, N.: Influence of specimen preparation, microstructure anisotropy, and residual stresses on stress-strain curves of rolled Al 2024 T351 as derived from spherical indentation tests. J. Mater. Res. 24, 907 (2009).CrossRefGoogle Scholar
21.Werwer, M. and Cornec, A.: The role of superdislocations for modeling plastic deformation of lamellar TiAl. Int. J. Plast. 22, 1683 (2006).Google Scholar
22.Diegele, E., Jansohn, W., and Tsakmakis, C.: Finite deformation plasticity and viscoplasticity laws exhibiting nonlinear hardening rules, Part I: Constitutive theory and numerical integration. Comput. Mech. 25, 1 (2000).CrossRefGoogle Scholar
23.Huber, N. and Tsakmakis, C.: Experimental and theoretical investigation of the effect of kinematic hardening on spherical indentation. Mech. Mater. 27, 241 (1998).Google Scholar
24.Huber, N. and Tsakmakis, C.: A finite element analysis of the effect of hardening rules on the indentation test. J. Eng. Mater. Technol. 120, 143 (1998).CrossRefGoogle Scholar
25.Huber, N. and Tsakmakis, C.: Determination of constitutive properties from spherical indentation data using neural networks. J. Mech. Phys. Solids 47, 1569 (1999).Google Scholar
26.Tyulyukovskiy, E.: Identification of mechanical properties of metallic materials using the indentation method. Karlsruhe Institute of Technology (KIT), Scientific Report FZKA 7103 (PhD), Institut of Material Research, Karlsruhe, March 2005.Google Scholar
27.Scherrer-Rudiy, S.: Assessment of statistical uncertainties in material mechanics issues using the Bayes procedure. Karlsruhe Institute of Technology (KIT), Scientific Report FZKA 7491 (PhD), Institut of Material Research, Karlsruhe, March 2009.Google Scholar
28.Tabor, D.: The Hardness of Metals (Cambridge University Press, Cambridge, 2000).CrossRefGoogle Scholar
29.Werwer, M., Kabir, M.R., Cornec, A., and Schwalbe, K-H.: Fracture in lamellar TiAl simulated with the cohesive model. Eng. Fract. Mech. 74, 2615 (2007).CrossRefGoogle Scholar
30.Appel, F., Heckel, T.K., and Christ, H-J.: Electron microscope characterization of low cycle fatigue in a high strength multiphase titanium aluminide alloy. Int. J. Fat. 32, 792 (2010).CrossRefGoogle Scholar
31.Kabir, M.R., Cornec, A., and Brocks, W.: Simulation of quasi-brittle fracture of lamellar γTiAl using the cohesive model and a stochastic approach. Comput. Mater. Sci. 39, 75 (2007).CrossRefGoogle Scholar