Overview

The Fourteenth International Symposium on Effects of Radiation on Materials was held on 27-30 June 1988 in Andover, MA. This biennial symposium series commenced in 1956 and has served as a major international forum for the exchange and discussion of both the fundamental and technological aspects of behavioral changes in materials exposed to radiation environments. The high level of participation at the latest symposium required four full days of conference sessions, and the peer-reviewed proceedings are being published in three volumes. The papers from the first three days of the symposium appear in the two volumes of this ASTM Special Technical Publication (STP) 1046. Volume [ encompasses radiation damageinduced microstructures; point defect, solute, and gas atom effects; atomic-level measurement techniques; and applications of theory. Volume II includes mechanical behavior, all papers dealing with pressure-vessel steels, breeder reactor components, dosimetry, and nuclear fuels. The fourth day of the symposium was devoted to the single topic of reducedactivation materials, including austenitic, ferritic, and vanadium alloys, for future fusion reactors; these papers are being published in a companion volume: ASTM STP 1047, Reduced-Activation Materials .for Fusion Reactors. The first two sections of Volume I, Microstructures: Ferritics and Microstructures: Austenitics, deal with the effects of radiation on the structures of alloys being developed for high-dose environments, such as the first wall of a fusion reactor. One notable theme is the profound influence of certain -minor" (that is, present in low concentration) but critical alloying elements, such as titanium, phosphorous, and others, primarily through the unique phases and microstructures they induce. Examples are offered of fine dispersions of precipitates acting as distributed point defect and gas atom traps with the result that the growth of large voids or bubbles is inhibited. Both neutron and charged-particle irradiations have been employed in these papers, while analytical transmission electron microscopy (TEM) seems to be the major technique of investigation. In Gas Effects, a large number of papers (12) explore various aspects of what is probably the most pernicious nuclear transmutation product, helium. If it is not hindered from collecting in bubbles at grain boundaries, the frequent result is helium embrittlement, which becomes a principal constraining factor for operation at high irradiation temperatures. Among the papers presented are studies of helium embrittlement in ferritic alloys, in pure nickel and nickel-base alloys, a direct comparison between austenitic and martensitic steels, helium effects in the different regions of stainless steel welds, and bubble formation in pure copper and aluminum. There are also fundamental studies of bubble formation for various inert gas species, and a technique paper offering a new way to introduce helium in mixedspectrum reactor experiments by the use of nickel-bearing foils adjacent to the specimens. The section on Radiation-Induced Segregation or Phase Changes is an important one