Journal of Nuclear Materials 195 (1992) 11-16 North-Holland Dispersoid stability in a Cu-Al,O, alloy under energetic cascade damage conditions S.J. Zinkle zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Metals and Ceramics Dicision, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6376, USA A. Horsewell and B.N. Singh Materials Departmerit, Rise National Laboratory, P.O. Box 49, DK-4000 Roskilde, D&mark W.F. Sommer Los Alamos National Laboratory, P.O. Box 1463, Los Alamos, NM 87545, USA Received 21 April 1992; accepted 12 June 1992 A commercial dispersion-strengthened Cu-AI,O, alloy was irradiated with 750-MeV protons at 470 K to a damage level of about 2 displacements per atom (dpa). The density and size distribution of the AI,O, particles was measured in nonirradiated and irradiated specimens using transmission electron microscopy. The mean primary knock-on atom (PKA) energy for 750-MeV protons in copper is 2.5 MeV, which is about 10 and 100 times higher than the average PKA energies in copper for fusion and fission neutrons, respectively. The irradiation caused only a slight decrease in the mean AI,O, size, from 10.5 nm to 8.3 nm, and a slight decrease in the particle density from 4x lO**/m’ to 3 x lO**/m’. zyxwvutsrqponmlkjihgfed 1. Introduction Dispersion-strengthened copper alloys are of tech- nological interest due to their combination of high thermal and electrical conductivity with high mechani- cal strength [ 11.These alloys are processed by introduc- ing a low volume fraction (typically I 1%) of a chemi- cally inert particulate phase into a pure copper matrix. High strength is achieved by heavy cold working, which produces a dense dislocation structure that is effec- tively pinned by the dispersoid particles. Dispersion- strengthened copper alloys have been shown to be resistant to recrystallization for annealing tempera- tures that approach the melting temperature of the copper matrix [2,3]. Conventionally processed high- conductivity precipitation-strengthened copper alloys, in contrast, generally begin to lose their strength fol- lowing annealing above 0.5T, (680 K) due to precipi- tate overaging effects [3,4]. The high density of dispersoid particles and disloca- tions present in dispersion-strengthened copper sug- gests that it should be microstructurally stable during irradiation, since most of the mobile defects produced by the irradiation would be annihilated at these defect sinks. Indeed, recent ion [5,6] and fission neutron [3,7-91 irradiation studies have shown that dispersion- strengthened copper alloys such as Cu-Al,O, retain their high strength and are resistant to radiation- induced cavity swelling even at high doses (100 dpa) and high temperatures. The radiation stability at high temperature is particularly significant since most pre- cipitation-strengthened copper alloys suffer radiation- enhanced recrystallization during irradiation at tem- peratures above 573 K with an accompanying dramatic decrease in mechanical strength [5,9-111. Dispersion- strengthened copper, in contrast, is generally resistant to radiation-enhanced recrystallization [3 5 6 8 91. , 9 9 9 For fusion energy applications, one underlying con- cern is the stability of the dispersoid particles against ballistic dissolution due to the highly energetic dis- placement cascades associated with fusion neutrons [5,8]. This would allow radiation-enhanced recrystal- 0022-3115/92/$05.00 0 1992 - Elsevier Science Publishers B.V. All rights reserved