Shear-coupled grain-boundary migration dependence on normal strain/stress

Nicolas Combe (1) , Frédéric Mompiou (2) , Marc Legros (2)

1 CEMES-SINanO - Surfaces, Interfaces et Nano-Objets
2 CEMES-PPM - Physique de la Plasticité et Métallurgie

In specific conditions, grain boundary (GB) migration occurs in polycrystalline materials as an alternative vector of plasticity compared to the usual dislocation activity. The shear-coupled GB migration, the expected most efficient GB based mechanism, couples the GB motion to an applied shear stress. Stresses on GB in polycrystalline materials have however seldom a unique pure shear component. This work investigates the influence of a normal strain on the shear coupled migration of a Σ13(320)[001] GB in a copper bicrystal using atomistic simulations. We show that the yield shear stress inducing the GB migration strongly depends on the applied normal stress. Beyond, the application of a normal stress on this GB qualitatively modifies the GB migration: while the Σ13(320)[001] GB shear-couples following the 110 migration mode without normal stress, we report the observation of the 010 mode under a sufficiently high tensile normal stress. Using the Nudge Elastic Band method, we uncover the atomistic mechanism of this 010 migration mode and energetically characterize it.

Domaines: Mécanique des matériaux [physics.class-ph]; Science des matériaux [cond-mat.mtrl-sci]

Nicolas Combe, Frédéric Mompiou, Marc Legros. Shear-coupled grain-boundary migration dependence on normal strain/stress. Physical Review Materials, 2017, 1, pp.033605. ⟨10.1103/PhysRevMaterials.1.033605⟩. ⟨hal-01726446⟩