Abstract：
In nuclear reactors, neutron or proton irradiation can generate damage as high as a few hundred displacements per atom (dpa) over the years. The primary radiation damage event in metals is displacement of atoms and the consequent formation of Frenkel (vacancy-interstitial) pairs and various aggregates of defects such as interstitial loops, voids, He bubbles and stacking fault tetrahedra. The extreme radiation environment poses a serious challenge for the application of metallic materials in advanced nuclear reactors. For instance defects clusters, such as He bubbles, voids and interstitial loops typically induce significant strengthening accompanied by swelling and embrittlement in irradiated materials. Advanced materials that can sustain severe radiation environment (hundreds of dpa over 80 years) are necessary to ensure the safety and achievement of maximum benefit of nuclear reactors. Here I will review several case studies on He and heavy ion irradiation induced damage in nanostructured metals. In the first few cases, metallic multilayers that show extraordinary radiation tolerance will be discussed. Appropriate design of layer interfaces is crucial to achieve enhanced radiation tolerance. Finally radiation response of bulk ultra-fine grained austenitic stainless steels will be presented. Implications from these studies and mechanisms of enhanced radiation tolerance will be discussed.

Biosketch：
Dr. Xinghang Zhang is an associate professor at Texas A&M University. Shortly after his Ph.D. at North Carolina State University in 2001, he was awarded the Director’s postdoctoral fellowship at Los Alamos National Laboratory. In 2005, he joined Texas A&M University as an assistant professor. His research expertise includes radiation damage in nanostructured metals, processing of advanced metallic materials, nanomechanics and various advanced microscopy technique, including in situ nanoindentation and in situ radiation in TEM. He has published over 100 journal articles, and is a key reader for Metallurgical and Materials Transaction, A. He was awarded the NSF early career award in 2007 and outstanding graduate teaching award at Texas A&M University. He has supervised over 15 graduate students, among which three are currently postdoctors at Los Alamos National Laboratory.