Effects of Size on the Dynamics of Dislocations in Ice Single Crystals

V. Taupin (1) , S. Varadhan (2) , J. Chevy (3) , C. Fressengeas (1) , A.J. Beaudoin (2) , Maurine Montagnat (3) , Paul Duval (3)

1 LPMM - Laboratoire de physique et mécanique des matériaux
2 MIE - Department of Mechanical and Industrial Engineering
3 LGGE - Laboratoire de glaciologie et géophysique de l'environnement

Single crystals of ice subjected to primary creep in torsion exhibit a softening behavior: the plastic strain rate increases with time. In a cylindrical sample, the size of the radius affects this response. The smaller the radius of the sample becomes while keeping constant the average shear stress across a section, the softer the response. The size-dependent behavior is interpreted by using a field dislocation theory, in terms of the coupled dynamics of excess screw dislocations gliding in basal planes and statistical dislocations developed through cross slip occurring in prismatic planes. The differences in the results caused by sample height effects and variations in the initial dislocation microstructure are discussed.

Domains: Glaciology

V. Taupin, S. Varadhan, J. Chevy, C. Fressengeas, A.J. Beaudoin, et al.. Effects of Size on the Dynamics of Dislocations in Ice Single Crystals. Physical Review Letters, 2007, 99 (155507), 1 à 4 p. ⟨10.1103/PhysRevLett.99.155507⟩. ⟨insu-00377504⟩