Growth and shrinkage of precipitates under irradiation

Abstract

The growth of second phase precipitates from the supersaturated solid solution under irradiation is investigated taking into account a new mechanism of precipitate dissolution. This mechanism is of a purely diffusion origin, i.e. it is based on diffusion outfluxes of point defects produced by irradiation within the precipitates into the host matrix, provided that the interface boundary is transparent for the point defects.

The point defect production rate within a precipitate is proportional to its volume while the total diffusion influx of substitutional impurity atoms is proportional to its radius meaning that there exists a maximum size at which the precipitate growth rate equals the rate of its radiation-induced dissolution. This size is shown to be a stable one implying that under irradiation a stationary state can be achieved far away from the thermodynamic equilibrium.

Key words:

• Precipitates
• diffusion
• point-defects
• irradiation