Phase-field study of ripening and rearrangement of precipitates under chemomechanical coupling
C. Schwarze, A. Gupta, T. Hickel, R. Darvishi Kamachali,
Volume: 95.
DOI: 10.1103/PhysRevB.95.174101
Published: 2017
Abstract
We investigate the evolution of large number of δ′ coherent precipitates
from a supersaturated Al-8 at.% Li alloy using large-scale phase-field
simulations. A chemomechanical cross-coupling between mechanical
relaxation and diffusion is taken into account by considering the
dependence of elastic constants of the matrix phase onto the local
concentration of solute atoms. The elastic constants as a function
of solute concentration have been obtained using density functional
theory calculations. As a result of the coupling, inverse ripening
has been observed where the smaller precipitates grow at the expense
of the larger ones. This is due to size-dependent concentration gradients
existing around the precipitates. At the same time, precipitates
rearrange themselves as a consequence of minimization of the total
elastic energy of the system. It is found that the anisotropy of
the chemomechanical coupling leads to the formation of new patterns
of elasticity in the matrix thereby resulting in new alignments of
the precipitates.