Stress concentrator at the plate-like inclusion tip as an enhancement factor of diffusion flux

Abstract

The work aims to evaluate stress-assisted effects in the diffusion growth of plate-like inclusions. We estimate the correction for diffusion flux onto plate-like inclusion tip accounting for the mechanical stress produced by phase transition. Also, the external stress effect on the stress-concentrator and upper-bound flux is evaluated. The stress factor results in the shift of solubility measured as the mean concentration in solution at precipitation. The impact of the stress concentrator was estimated for different thermodynamic systems: θ′-phase (Al2Cu) growth in Al-Cu alloy, zirconium hydrides growth, and perlitic transformation. The stress factor could play a sufficient role in nonstationary conditions and is negligible in steady-state approximation. Stress factor can also have substantial effects on the inclusion orientation if an external stress is present: rigid inclusion lengthening parallel to the external stress, while stacks of inclusions can behave differently depending on nucleation barriers competition for shear and hydrostatic stress components.