Dislocation formation in two-phase alloys

Abstract

A phase field model is presented to study dislocation formation (coherency loss) in two-phase binary alloys. In our model the elastic energy density is a periodic function of the shear and tetragonal strains, which allows multiple formation of dislocations. The composition is coupled to the elastic field twofold via lattice misfit and via composition-dependence of the elastic moduli. By numerically integrating the dynamic equations in two dimensions, we find that dislocations appear in pairs in the interface region and grow into slips. One end of each slip glides preferentially into the softer region, while the other end remains trapped at the interface. Under uniaxial stretching at deep quenching, slips appear in the softer region and do not penetrate into the harder domains, giving rise to a gradual increase of the stress with increasing applied strain in plastic flow.

Effect of dislocations on spinodal decomposition in Fe–Cr alloys

“…Recently, phase-field simulations have been conducted to study spinodal decomposition in alloys with dislocations [13][14][15] and to investigate dislocation formation and dislocation dynamics [16][17][18][19]. For instance, Léonard and Desai [13] conducted phasefield simulations of spinodal decomposition in an isotropic alloy with dislocations.…”

Modeling microstructure evolution of binary systems subjected to irradiation and mechanical loading

“…In further consideration we exploit the phase field model for two-phase binary system (see [10,[20][21][22]). According to this model point defects are not taken into account directly as separated substances.…”

“…Recently, the phase field approach allowing one to describe the formation of dislocations in binary alloys was proposed in Refs. [10,20]. This model represents generalization of the well-known Cahn and Khachaturyan approaches, where shear modulus is a composition-dependent function.…”

“…In Refs. [20][21][22] it was shown that Cottrell atmosphere is formed around dislocations cores, where edge dislocations in the developed continuum approach have opposite Burgers vectors.…”

“…[10,[20][21][22][23][24]. Here, we consider a model of a binary alloy with separated phases with a coherent interface and assume that this coherency can be broken due to defects production at irradiation leading to ballistic atomic mixing [10,[25][26][27].…”