b'Figure 2. TEM image Cu/Nb composite after 5MeVCu irradiation at 400oC to 100 dpa. Layer structured is well preserved with no indication of mixing.completed investigating the layer size,increase in layer size were observed. morphology, and texture (J. Cheng, M.Since this was observed on unirradi-Radhakrishnan, N. Mara, O. Anderoglu).ated layers as well, it was thought to be To establish structure-property relations,thermally driven.mechanical testing as a function of layerIn Zr/Nb, the irradiation caused thickness including at high temperatureschemical mixing of layers in all the (M. Radhakrishnan, O. Anderoglu) aslayer thicknesses studied and the mixed well as thermal conductivity measure- layer thickness extended to multiple ments were completed (M. Khafizov,bi-layer periods. The observed mixing is Ohio State U.). Mechanical testing wasattributed to the liquid phase interdiffu-also completed perpendicular to layersion within thermal spikes, and a stable thickness (J. Gigax, LANL) showingmixed layer was favored by the liquid-similar results as parallel to layerphase miscibility of Zr and Nb.thickness measurements. High dose irradiations were completed at 400C (200 dpa) and 600C (450 dpa) (O. Anderoglu, UNM; Y. Wang, LANL; MIBL, U of Michigan). Detailed investigations including TEM and Atom Probe Tomog-raphy (APT) were performed. Cu/Nb: 5MeV Cu irradiations at 400C up to 200 dpa (~200nm below the surface) did not show any voids but some clusters presumably due to ballistic collisions were found on both Cu and Nb layers. However, at 600C and 450 dpa, although no cavities were obtained, Figure 3. Dark field TEM and APT of Zr irradiated Zr/Nb showing mixing of the layers2021|AFC ACCOMPLISHMENTS 113'