Specimens of the pure metal were irradiated with 2.4MeV Cu2+ ions, to up to 3dpa, at temperatures between ambient and 1073K. Transmission electron microscopy and micro-indentation tests were used to correlate the microstructure to the hardness. Appreciable radiation hardening occurred at temperatures ranging from 673 to 873K. Isochronal annealing of a specimen which was irradiated at room temperature, up to a dose of 0.3dpa, resulted in a rapid increase in hardening between 573 and 673K. It continued to increase up to 873K. The microstructures showed that the formation of small defect clusters was the major reason for radiation-hardening and radiation-anneal hardening.

Correlation between Defect Structures and Hardness in Tantalum Irradiated by Heavy Ions. K.Yasunaga, H.Watanabe, N.Yoshida, T.Muroga, N.Noda: Journal of Nuclear Materials, 2000, 283-287, 179-82