The influence of Helium bubbles on the critical resolved shear stress of dispersion strengthened alloys

Abstract

Dispersoid strengthening is particularly important for ferritic based structural components used in nuclear applications due to their superior radiation resistance and creep strength at high temperatures. Within nuclear technologies yttrium particles dispersed throughout the matrix are the most promising ferritic steels to achieve these improved materials properties by acting as obstacles to dislocation motion. Due to radiation damage in these alloys considerable production of helium bubbles can be observed. Their amalgamation into large structures can be detrimental to the material’s lifetime and it is therefore important to understand how their interaction with other defects can be controlled and what effect their presence has. Increased computational power now allows the direct study of such dislocation-obstacle interactions using 3D Discrete Dislocation Dynamics simulations at the mesoscale. In this work the effect of helium bubbles in irradiated dispersion strengthened ferritic steels and the response of the critical resolved shear stress is studied and found to increase with the density of helium bubbles.