Evolution of helium bubbles induced by stress concentration in He-irradiated aluminium

Abstract

By employing an in-situ tension experiment in a transmission electron microscope, a stress concentration is demonstrated as a significant contributor to evolution of helium bubbles in a non-uniform stress field. In the stress concentration, a bubble growth occurs through bubble migration and coalescence driven by stress gradients as well as a dislocation slip-induced vacancy absorption upon straining. A bubble-shape evolution occurs after a coalescence of bubbles with similar size. As the bubbles grow to critical sizes, gradual elongation and disappearance of bubbles are found with further straining.