exist for metallic systems • less difficult - can probe the effect of structure on mass transport • Initial focus on • interfaces of immiscible fcc-bcc semicoherent metal systems Cu-Nb, Cu-V, Cu-Mo, Cu-Fe, and Ag-V (111) fcc (110) bcc || ʪ110ʫ fcc ʪ111ʫ bcc || and Kurdjumov-Sachs (KS): (111) fcc (110) bcc || ʪ110ʫ fcc ʪ100ʫ bcc || and Nishiyama-Wassermann (NW): Motivated by experiments A. Misra et al., JOM, Sept, 62 (2007) Interfaces act as obstacles to slip and sinks for radiation-induced defects. Hence, nanolayered composites that contain a large volume fraction of inter- faces provide over an order of magnitude increase in strength and enhanced radia- tion damage tolerance compared to bulk materials. This paper shows the experi- mental and atomistic modeling results from a Cu-Nb nanolayered composite to highlight the roles of nanostructur- ing length scales and the response of interfaces to ion collision cascades in designing composite materials with high radiation damage tolerance. INTRODUCTION The performance of materials in extreme environments of irradiation and temperature must be signifi cantly improved to extend the reliability, life- time, and effi ciency of future nuclear reactors.1 In reactor environments, damage introduced in the form of radia- The Radiation Damage Tole of Ultra-High Strength Nan Composites A. Misra, M.J. Demkowicz, X. Zhang, and R.G. Hoagland interfaces are to act as sinks for radia- tion-induced defects. Studies conducted on sputter-deposited Cu-Nb multilayers b a 150 keV He, 1017 cm-2, 300 K After He implantation