An Elastic-Visco-Plastic Deformation Model of Al–Li with Application to Forging

An Elastic-Visco-Plastic Deformation Model of Al–Li with Application to Forging

L.B. Borkowski J.A. Sharon  A. Staroselsky

United Technologies Research Center, East Hartford, CT

| |
| | Citation



Recent alloy developments have produced a new generation of Al–Li alloys that provide not only weight savings, but also many property benefits such as excellent corrosion resistance, good spectrum fatigue crack growth performance, a good strength and toughness combination and compatibility with standard manufacturing techniques. The forging of such alloys would lead to mechanical properties that closely match the aircraft engine requirements including lower weight, improved performance and a longer life. As a result, detailed analyses need to be performed to determine which material properties are best suited for a specific structure and how to achieve the required mechanical and damage tolerant properties during material processing.

We developed an integrated physics-based model for prediction of microstructure evolution and material property prediction of third-generation Al–Li alloys. In order to develop such a model, an elastic-plastic crystal plasticity model is developed and incorporated in finite element software (ANSYS). The model accounts for microstructural evolution during non-isothermal, non-homogeneous deformation and is coupled with the damage kinetics. Our model bridges the gap between dislocation dynamics and continuum mechanics scales.

Model parameters have been calibrated against lab tests including micropillar in-situ simple compression tests of Al–Li alloy 2070. Numerical predictions are verified against the lab results including stress–strain curves and crystallographic texture evolution.


crystallographic texture, light weight alloys, material characterization, material processing, micro-scale testing


[1] Encyclopedia of Energy Engineering and Technology 1, Barney L. Capehart CRC Press. ISBN 978-0-8493-3653-9, (2007).

[2] Lee, J.J, Historical and future trends in aircraft performance, cost and emissions, MS Thesis, Massachusetts Institute of Technology, Cambridge, 2000.

[3] Gupta, R.K., Nayan, N., Nagasireesha, G. & Sharma, S.C., Development and characterization of Al-Li alloys. Materials Science and Engineering, A420, pp. 228–234, 2006.

[4] Staroselsky, A. & Cassenti, B.N. Combined rate-independent plasticity and creep model for single crystal. Mechanics of Materials, 42(10), pp. 945–959, 2010.

[5] Staroselsky, A., Crystal plasticity due to slip and twinning, PhD Thesis, MIT, 1997.

[6] Stouffer, D.C. & Dame, L.T., Inelastic deformation of metals. John Wiley & Sons, Inc, New York, 1996.

[7] Staroselsky, A. & Cassenti, B.N., Mechanisms for tertiary creep of single crystal superalloy. Mechanics of Time-Dependent Materials, 12(4), pp. 275–289, 2008.

[8] Ng, K.S. & Ngan, A.H.W., Stochastic nature of plasticity of aluminum micro-pillars. Acta Materialia, 56(8), pp. 1712–1720, 2008.

[9] Kunz, A., Pathak, S. & Greer, J.R., Size effects in Al nanopillars: Single crystalline vs. bicrystalline. Acta Materialia, 59(11), pp. 4416–4424, 2011.

[10] Volkert, C.A. & Lilleodden, E.T., Size effects in the deformation of sub-micron Au columns. Philosophical Magazine, 86(33–35), pp. 5567–5579, 2006.

[11] Zhang, H., Schuster, B.E., Wei, Q. & Ramesh, K.T., The design of accurate microcompression experiments. Scripta Materialia, 54(2), pp. 181–186, 2006.

[12] Frick, C.P., Clark, B.G., Orso, S., Schneider, A.S. & Arzt, E., Size effect on strength and strain hardening of small-scale [1 1 1] nickel compression pillars. Materials Science and Engineering, A 489(1–2), pp. 319–329, 2008.

[13] Sneddon, I.N., The relation between load and penetration in the axisymmetric boussinesq problem for a punch of arbitrary profile. International Journal of Engineering Science, 3(1), pp. 47–57, 1965.

[14] Noble, B., Harris, S.J. & Dinsdale, K., The elastic modulus of aluminium-lithium alloys. Journal of Materials Science 17(2), pp. 461–468, 1982.

[15] Uchic, M.D., Shade, P.A. & Dimiduk, D.M., Plasticity of micrometer-scale single crystals in compression. Annual Review of Materials Research, 39, pp. 361-386, 2009.

[16] Greer, J.R., & De Hosson, J.T.M., Plasticity in small-sized metallic systems: Intrinsic versus extrinsic size effect. Progress in Materials Science, 56(6), pp. 654–724, 2011.

[17] McDowell, D. L., A perspective on trends in multiscale plasticity. International Journal of Plasticity, 26(9), pp. 1280–1309, 2010.

[18] Caillard, D. & Martin, J.L., Glide of dislocations in non-octahedral planes of fcc metals: a review. International Journal of Materials Research, 100(10), pp. 1403–1410, 2009.

[19] Contrepois, Q., Maurice, C. & Driver, J. H., Hot rolling textures of Al–Cu–Li and Al– Zn–Mg–Cu aeronautical alloys: experiments and simulations to high strains. Materials Science and Engineering: A, 527(27), pp. 7305–7312, 2010.

[20] Ringeval, S., Piot, D., Desrayaud, C. & Driver, J. H., Texture and microtexture development in an Al–3Mg–Sc (Zr) alloy deformed by triaxial forging. Acta Materialia, 54(11), pp. 3095–3105, 2006.