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Glide and climb resistance to the motion of an edge dislocation due to dragging a Cottrell atmosphere

1979; Taylor & Francis; Volume: 40; Issue: 1 Linguagem: Inglês

10.1080/01418617908234833

0141-8610

Shin Takeuchi, A. S. Argon,

Microstructure and mechanical properties

Abstract Steady viscous motion of a straight edge dislocation surrounded by a Cottrell atmosphere has been simulated by computer using a discrete lattice model. In the low-velocity range v≪DkT|A, the atmosphere exerts the same viscous force for any direction of dislocation motion, where D is the diffusion coefficient of the solute atom in the Bolvent and A is the interaction parameter given by (where v is the Poisson ratio, μ is the shear modulus, 6 is the Burgors vector, Ω is the atomic volume, and ∗ is the size-misfit parameter). The numerical factor x in the viscosity coefficient Ba = αA2c0/(ΩDkT) (where co is the atomic concentration of solute) for a typical case of AlkT = 2b (or b) at v= lO–2DkT/A is calculated to be 7 (or 4). The critical velocity ve at which the atmosphere produces a maximum dragging force Fm is approximately DkT∣A with Fs/ being of the order of Aco/Ω. In the high–velocity range of u≫ DkT|A, the dragging force for glide is expressed by F⋍ 5c0≫(Ωb2kTv).