Formation of persistent shear in model amorphous covalent system from molecular dynamics
Tristan Albaret (Université Lyon 1, France), Anne TANGUY (Université Lyon 1)
Slip Avalanches in Amorphous Metals
Mon 10:45 - 12:15
Barus-Holley 168
Our understanding of plasticity in amorphous solids at small scales largely rely on the shear transformation zones (STZ) (1-2] which represent elementary deformation units involving few tens of atoms. From the perspective of the elasticity of a continuous medium, these elementary deformations are associated with quadrupolar events that appear as the solutions of the Eshelby inclusion problem [3]. In this presentation, I will discuss atomistic simulations performed with several interaction potentials in the quasi-static shear limit which is well suited to describe the low stain rate conditions. From the successive atomic configurations we first developped a technique to identify and characterize the plastic events that are generated upon shear[4]. Interestingly, this technique allowed us to recast our atomistic results in terms of quadrupolar events from which the atomistic strain-stress curves can be reproduced to a very good accuracy. In a second part I will focus on the shear band formation in our model amorphous covalent systems and discuss the role of both the coordination defects and the interatomic potential. Going sligthly beyond the quasi-static limit, we looked at the dynamical formation of the shear band close to the yield point where we observed a formation process that involves successively : isolated plastic events, one-dimensional arrangements of large plastic events and the creation of a two dimensional shear band. [1] A.S. Argon, Acta Metall. 27, 47 (1979). [2] P.S. Steif, F. Spaepen, J.W. Hutchinson, Acta Metall. 30, 447 (1982) [3] J.D. Eshelby, Proc. R. Soc. London, Ser. A 241, 376 (1957) [4] C. Fusco, T. Albaret and A. Tanguy, Phys. Rev. E 82, 066116 (2010)