Irradiation as a tool for studying solid-state amorphization phenomena

An overview of selected experimental results on amorphization induced by irradiation and by ion implantation is first presented. This overview and other general observations on the microstructural evolution that precedes the transition to the amorphous state of irradiated crystalline materials expose some of the important data that must be accounted for by theory. A perspective of our present understanding of irradiation-induced amorphization is then presented. As described in previous work, the theory assumes a localized buildup of complexes (coupled interstitial/ vacancy pairs) to a critical value as the mechanism of amorphization. The theory of complex formation implies that the production of a defective state characterized by localized anisotropic distortions of the crystalline lattice leads to amorphization. It is proposed that this concept can be generalized to encompass solid-state amorphization transitions other than those induced by irradiation. Examples available in the literature to support this idea are presented. It is therefore suggested that irradiation can be used as a valuable tool to study other solid-state amorphization transitions. This paper is based on a presentation made in the symposium “Irradiation-Enhanced Materials Science and Engineering” presented as part of the ASM INTERNATIONAL 75th Anniversary celebration at the 1988 World Materials Congress in Chicago, IL, September 25-29, 1988, under the auspices of the Nuclear Materials Committee of TMS-AIME and ASM-MSD.