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High-rate dislocation motion in stable nanocrystalline metals

  • Jeffrey T Lloyd (a1)

Abstract

Dislocation-mediated plasticity in stable nanocrystalline metals, where grain boundary motion is suppressed, is revisited in the context of dislocation elastodynamics. The effect of transient waves that emanate from the generation and motion of dislocations is quantified for an idealized Cu–10 at.% Ta system with grain sizes on the order of 50 nanometers. Simulations indicate that for this material, as dislocation velocities approach 0.6–0.8 times the shear wave speed, grains several grain diameters away from the initial glide event experience a large transient shear stress for a finite duration. These transient shear stresses increase with increasing glide velocity and can activate nucleation sites far from the original nucleation event. These considerations are used to explain recent experimental observations of a lack of increase in flow stress with increasing loading rate, as well as localization resistance, in this class of stable nanocrystalline metals.

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a)Address all correspondence to this author. e-mail: jeffrey.t.lloyd.civ@mail.mil

References

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1.Orowan, E.: Problems of plastic gliding. Proc. Phys. Soc. 52, 8 (1940).
2.Conrad, H.: Grain size dependence of the plastic deformation kinetics in Cu. Mater. Sci. Eng., A 341, 216228 (2003).
3.Wei, Q., Cheng, S., Ramesh, K., and Ma, E.: Effect of nanocrystalline and ultrafine grain sizes on the strain rate sensitivity and activation volume: Fcc versus bcc metals. Mater. Sci. Eng., A 381, 7179 (2004).
4.Argon, A. and Yip, S.: The strongest size. Philos. Mag. Lett. 86, 713720 (2006).
5.Dao, M., Lu, L., Asaro, R., De Hosson, J.T.M., and Ma, E.: Toward a quantitative understanding of mechanical behavior of nanocrystalline metals. Acta Mater. 55, 40414065 (2007).
6.Wei, Y., Bower, A., and Gao, H.: Enhanced strain-rate sensitivity in fcc nanocrystals due to grain-boundary diffusion and sliding. Acta Mater. 56, 17411752 (2008).
7.Zhang, K., Weertman, J., and Eastman, J.: Rapid stress-driven grain coarsening in nanocrystalline Cu at ambient and cryogenic temperatures. Appl. Phys. Lett. 87, 061921 (2005).
8.Koch, C., Scattergood, R., Darling, K., and Semones, J.: Stabilization of nanocrystalline grain sizes by solute additions. J. Mater. Sci. 43, 72647272 (2008).
9.Darling, K., Roberts, A.J., Mishin, Y., Mathaudhu, S.N., and Kecskes, L.J.: Grain size stabilization of nanocrystalline copper at high temperatures by alloying with tantalum. J. Alloys Compd. 573, 142150 (2013).
10.Darling, K., Huskins, E., Schuster, B., Wei, Q., and Kecskes, L.: Mechanical properties of a high strength Cu–Ta composite at elevated temperature. Mater. Sci. Eng., A 638, 322328 (2015).
11.Frolov, T., Darling, K., Kecskes, L., and Mishin, Y.: Stabilization and strengthening of nanocrystalline copper by alloying with tantalum. Acta Mater. 60, 21582168 (2012).
12.Koju, R., Darling, K., Solanki, K., and Mishin, Y.: Atomistic modeling of capillary-driven grain boundary motion in Cu–Ta alloys. Acta Mater. 148, 311319 (2018).
13.Darling, K., Rajagopalan, M., Komarasamy, M., Bhatia, M., Hornbuckle, B., Mishra, R., and Solanki, K.: Extreme creep resistance in a microstructurally stable nanocrystalline alloy. Nature 537, 378 (2016).
14.Regazzoni, G., Kocks, U., and Follansbee, P.: Dislocation kinetics at high strain rates. Acta Metall. 35, 28652875 (1987).
15.Turnage, S., Rajagopalan, M., Darling, K., Garg, P., Kale, C., Bazehhour, B., Adlakha, I., Hornbuckle, B., Williams, C., Peralta, P., and Solanki, K.: Anomalous mechanical behavior of nanocrystalline binary alloys under extreme conditions. Nat. Commun. 9, 2699 (2018).
16.Lin, I., Hirth, J., and Hart, E.: Plastic instability in uniaxial tension tests. Acta Metall. 29, 819827 (1981).
17.Wei, Q.: Strain rate effects in the ultrafine grain and nanocrystalline regimes influence on some constitutive responses. J. Mater. Sci. 42, 17091727 (2007).
18.Darling, K., Tschopp, M., Guduru, R., Yin, W., Wei, Q., and Kecskes, L.: Microstructure and mechanical properties of bulk nanostructured Cu–Ta alloys consolidated by equal channel angular extrusion. Acta Mater. 76, 168185 (2014).
19.Bhatia, M., Rajagopalan, M., Darling, K., Tschopp, M., and Solanki, K.: The role of Ta on twinnability in nanocrystalline Cu–Ta alloys. Mater. Res. Lett. 5, 4854 (2017).
20.Clifton, R.: On the analysis of elastic/visco-plastic waves of finite uniaxial strain. In Shock Waves and the Mechanical Properties of Solids, Burke, J. and Weiss, V., eds. (Syracuse University Press, Syracuse, New York, 1971); pp. 73116.
21.Kocks, U., Argon, A., and Ashby, M.: Thermodynamics and kinetics of slip. Prog. Mater. Sci. 19, 1281 (1975).
22.Kuhlmann-Wilsdorf, D.: Theory of plastic deformation: Properties of low energy dislocation structures. Mater. Sci. Eng., A 113, 141 (1989).
23.Taylor, J.: Dislocation dynamics and dynamic yielding. J. Appl. Phys. 36, 31463150 (1965).
24.Johnston, W. and Gilman, J.: Dislocation multiplication in lithium fluoride crystals. J. Appl. Phys. 31, 632643 (1960).
25.Gupta, Y., Duvall, G., and Fowles, G.: Dislocation mechanisms for stress relaxation in shocked LiF. J. Appl. Phys. 46, 532546 (1975).
26.Roters, F., Raabe, D., and Gottstein, G.: Work hardening in heterogeneous alloys—A microstructural approach based on three internal state variables. Acta Mater. 48, 41814189 (2000).
27.Johnston, W. and Gilman, J.: Dislocation velocities, dislocation densities, and plastic flow in lithium fluoride crystals. J. Appl. Phys. 30, 129144 (1959).
28.Yamakov, V., Wolf, D., Phillpot, S., Mukherjee, A., and Gleiter, H.: Dislocation processes in the deformation of nanocrystalline aluminium by molecular-dynamics simulation. Nat. Mater. 1, 45 (2002).
29.Jones, O. and Mote, J.: Shock-induced dynamic yielding in copper single crystals. J. Appl. Phys. 40, 49204928 (1969).
30.Johnson, J., Jones, O., and Michaels, T.: Dislocation dynamics and single crystal constitutive relations: Shock-wave propagation and precursor decay. J. Appl. Phys. 41, 23302339 (1970).
31.Austin, R. and McDowell, D.: A dislocation-based constitutive model for viscoplastic deformation of fcc metals at very high strain rates. Int. J. Plast. 27, 124 (2011).
32.Lloyd, J., Clayton, J., Austin, R., and McDowell, D.: Plane wave simulation of elastic-viscoplastic single crystals. J. Mech. Phys. Solids 69, 1432 (2014).
33.Lloyd, J., Clayton, J., Becker, R., and McDowell, D.: Simulation of shock wave propagation in single crystal and polycrystalline aluminum. Int. J. Plast. 60, 118144 (2014).
34.Austin, R.: Elastic precursor wave decay in shock-compressed aluminum over a wide range of temperature. J. Appl. Phys. 123, 035103 (2018).
35.Zhu, T., Li, J., Samanta, A., Leach, A., and Gall, L.: Temperature and strain-rate dependence of surface dislocation nucleation. Phys. Rev. Lett. 100, 025502 (2008).
36.Van Swygenhoven, H., Derlet, P., and Froseth, A.: Nucleation and propagation of dislocations in nanocrystalline fcc metals. Acta Mater. 54, 19751983 (2006).
37.Zhu, T., Li, J., Samanta, A., Kim, H., and Suresh, S.: Interfacial plasticity governs strain rate sensitivity and ductility in nanostructured metals. Proc. Natl. Acad. Sci. U. S. A. 104, 30313036 (2007).
38.Zhu, T. and Li, J.: Ultra-strength materials. Prog. Mater. Sci. 55, 710757 (2010).
39.Lee, T., Robertson, I., and Birnbaum, H.: Prediction of slip transfer mechanisms across grain boundaries. Scr. Metall. 23, 799803 (1989).
40.Hunter, A., Leu, B., and Beyerlein, I.: A review of slip transfer: Applications of mesoscale techniques. J. Mater. Sci. 53, 55845603 (2018).
41.Weertman, J.: High velocity dislocations. In Response of Metals to High Velocity Deformation. Metallurgical Society Conferences, Vol. 9, Shewmon, P. and Zackay, V., eds. (Interscience, New York, 1961); pp. 205249.
42.Clifton, R. and Markenscoff, X.: Elastic precursor decay and radiation from nonuniformly moving dislocations. J. Mech. Phys. Solids 29, 227251 (1981).
43.Gurrutxaga-Lerma, B., Balint, D., Dini, D., and Sutton, A.: The mechanisms governing the activation of dislocation sources in aluminum at different strain rates. J. Mech. Phys. Solids 84, 273292 (2015).
44.Greenman, W., Vreeland, T. Jr., and Wood, D.: Dislocation mobility in copper. J. Appl. Phys. 38, 35953603 (1967).
45.Chen, J., Tschopp, M., and Dongare, A.: Shock wave propagation and spall failure of nanocrystalline Cu/Ta alloys: Effect of Ta in solid-solution. J. Appl. Phys. 122, 225901 (2017).
46.Joshi, S. and Ramesh, K.: Stability map for nanocrystalline and amorphous materials. Phys. Rev. Lett. 101, 025501 (2008).
47.Guo, Y., Li, Y., Pan, Z., Zhou, F., and Wei, Q.: A numerical study of microstructure effect on adiabatic shear instability: Application to nanostructured/ultrafine grained materials. Mech. Mater. 42, 10201029 (2010).
48.Eshelby, J.: Uniformly moving dislocations. Proc. Phys. Soc. 62, 307 (1949).
49.Van der Giessen, E. and Needleman, A.: Discrete dislocation plasticity: A simple planar model. Modell. Simul. Mater. Sci. Eng. 3, 689 (1995).
50.Gurrutxaga-Lerma, B., Balint, D., Dini, D., Eakins, D., and Sutton, A.: Dynamic discrete dislocation plasticity. In Advances in Applied Mechanics, Bordas, S., ed. Vol. 47 (Elsevier, London, U.K., 2014); ch. 2, pp. 93224.
51.Markenscoff, X. and Clifton, R.: The nonuniformly moving edge dislocation. J. Mech. Phys. Solids 29, 253262 (1981).
52.Gurrutxaga-Lerma, B., Balint, D., Dini, D., Eakins, D., and Sutton, A.: A dynamic discrete dislocation plasticity method for the simulation of plastic relaxation under shock loading. Proc. R. Soc. A 469, 20130141 (2013).
53.Darling, K., Kale, C., Turnage, S., Hornbuckle, B., Luckenbaugh, T., Grendahl, S., and Solanki, K.: Nanocrystalline material with anomalous modulus of resilience and springback effect. Scr. Mater. 141, 3640 (2017).

Keywords

High-rate dislocation motion in stable nanocrystalline metals

  • Jeffrey T Lloyd (a1)

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