Phase-field calculations of sink strength in Al, Ni, and Fe: A detailed study of elastic effects

Abstract

The sink strength and bias of edge dislocations, low-angle symmetric tilt grain boundaries (STGBs), and spherical cavities are calculated for Al, Ni and Fe using a phase-field approach in this work. The interactions between point defects (PDs) and sinks are incorporated in the present model. These interactions include an elastic contribution to the total free energy of the system, and the phenomenon of elastodiffusion which is often ignored and consists in the modification of the PD migration energy due the strain field generated by the sink. Specific spatial schemes and new algorithms have been developed and applied to perform the calculations due to the PD diffusion which becomes anisotropic and spatial dependent when elastodiffusion is taken into account. The results obtained show that the solution of Rauh and Simon systematically underestimates the sink strength of edge dislocations, especially for dumbells in Ni and Fe. STGBs with low misorientation angle and high density are biased sinks when elasticity (with and without elastodiffusion) is taken into account. It is also shown that taking into account the PD anisotropy at saddle point when the elastodiffusion is considered leads to a significant bias (>10%) of the cavity, which thus highlights the importance of the PD anisotropy at saddle point on the sink strength and bias calculations.