Possible Mechanisms Limiting the Pressure in Inert Gas Bubbles in Metals

Abstract

When inert gases are introduced into metals by nuclear transmutation or ion implantation they precipitate as bubbles because of their low solubility. At temperatures below about 0.25 of the melting temperature of the metal, the pressure within these bubbles is limited either by dislocation loop punching or by the displacement damage associated with implantation. Theory predicts that the minimum pressure at which dislocation loop punching can occur is of the order of the theoretical shear strength of the matrix. It is shown that this is confirmed by recent precision dilatometry of tritided metals. The lower pressure values in solid inert gas bubbles forming during ion implantation of heavy inert gases (Ar, Kr, Xe) into metals are attributed to a displacement damage induced creep process which is described by a phenomenological approach. The results of a detailed data analysis are used to calibrate spectroscopic measurements on bubbles forming during helium implantation.