Neutron irradiation scoping study of twenty-five copper-base materials
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I. INTRODUCTION Various fusion reactor structural components require alloys that exhibit elevated temperature strength, thermal shock resistance, and high thermal and electrical conductivity. Copper-rich alloys have been recognized as candidates for such service,1 having demonstrated desirable combinations of properties in applications such as resistance welding electrodes, highvoltage switches, motor commutators, continuous casting molds, and heat exchangers. Improvement over existing commercial copper alloys may be necessary for fusion reactor service requirements and those of other potential applications with high performance requirements, such as water-cooled gas turbine blades2 and accelerator targets.3 Establishing the potential of copper alloys for fusion reactor environments requires a data base on the irradiated properties of candidate alloys at relevant fluences and temperatures. In a fusion reactor, components of copper alloys located at or near to the first wall structure would be exposed to neutron damage levels in excess of 15 dpa/yr at temperatures up to about 400 °C. Neutron irradiation investigations of copper, however, have until recently been limited to basic studies of the primary damage structure in pure copper after low dose ( < 1 dpa) irra568
J. Mater. Res. 2 (5), Sep/Oct 1987
http://journals.cambridge.org
diations, usually performed at cryogenic temperatures. To address the need for higher fluence data at potential fusion reactor service temperatures, we initiated an irradiation scoping experiment using 25 different copperbased materials. A number of the alloy systems tested have the potential to fulfill fusion structural component requirements, including high conductivity, ability to withstand brazing and joining temperatures without significant loss of strength, and adequate strength and ductility over a range of temperature from 293 K to at least 673 K. The materials include commercially available alloys, high performance experimental alloys produced by rapid solidification technology (RST), and several "pure" copper materials for comparison purposes. Specimens were precision-machined disks of the size commonly used for transmission electron microscopy (TEM), 3 mm diam by 0.25 mm thick. The irradiation was carried out in a helium gas-filled capsule at 4 0 0 + 1 0 °C in the Experimental Breeder Reactor II (EBR-II). Damage levels of 13.5 dpa were achieved. Microscopic and macroscopic characterizations of the specimens were carried out to investigate irradiationinduced changes in engineering properties. In this article we provide, in Sec. II, a brief overview of relevant copper alloy metallurgy and a description of the materials chosen for the scoping experiment. In Sec.
0003-6951 /87/050568-12S01.75
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© 1987 Materials Research Society
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Harling eta/.: Neutron study of copper-base materials
III we provide information on pre- ahd post-irradiation conductivities, swelling, mechanical properties, and initial results of microstructural studies
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