Radiation tolerance of nanotwinned metals – An atomistic perspective

Abstract

Remarkable properties of ultra-high strength, ductility, and stability have been achieved through the introduction of twin boundaries in nanostructured metals. Here, we report molecular dynamics simulations which elucidate the synergistic role of grain boundaries and twin boundaries in enhancing the radiation tolerance of nanotwinned metals. While grain boundaries are known to be excellent sinks for point defects, coherent twin boundaries do not absorb point defects. A beneficial corollary is that the structural integrity of coherent twin boundaries remains intact as radiation-induced defects pass through them and ultimately get absorbed into grain boundaries. Hence, the twin boundaries can continue to play a role in imparting high strength even after being subjected to irradiation. Thus, nanotwinned structures may indeed be optimal motifs for radiation tolerant materials that preserve high strength and ductility.