title: Considerable knock-on displacement of metal atoms under a low energy electron beam.
abstract: Under electron beam irradiation, knock-on atomic displacement is commonly thought to occur only when the incident electron energy is above the incident-energy threshold of the material in question. However, we report that when exposed to intense electrons at room temperature at a low incident energy of 30 keV, which is far below the theoretically predicted incident-energy threshold of zirconium, Zircaloy-4 (Zr-1.50Sn-0.25Fe-0.15Cr (wt.%)) surfaces can undergo considerable displacement damage. We demonstrate that electron beam irradiation of the bulk Zircaloy-4 surface resulted in a striking radiation effect that nanoscale precipitates within the surface layer gradually emerged and became clearly visible with increasing the irradiation time. Our transmission electron microscope (TEM) observations further reveal that electron beam irradiation of the thin-film Zircaly-4 surface caused the sputtering of surface α-Zr atoms, the nanoscale atomic restructuring in the α-Zr matrix, and the amorphization of precipitates. These results are the first direct evidences suggesting that displacement of metal atoms can be induced by a low incident electron energy below threshold. The presented way to irradiate may be extended to other materials aiming at producing appealing properties for applications in fields of nanotechnology, surface technology, and others.
authors.affiliation: Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China.|University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing, 100049, People's Republic of China.
authors.forename: Hengfei
authors.initials: H
authors.lastname: Gu
authors.affiliation: Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China. gpli@imr.ac.cn.|University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026, People's Republic of China. gpli@imr.ac.cn.
authors.forename: Geping
authors.initials: G
authors.lastname: Li
authors.affiliation: Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China.|University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026, People's Republic of China.
authors.forename: Chengze
authors.initials: C
authors.lastname: Liu
authors.affiliation: Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China.|University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026, People's Republic of China.
authors.forename: Fusen
authors.initials: F
authors.lastname: Yuan
authors.affiliation: Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China.|University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026, People's Republic of China.
authors.forename: Fuzhou
authors.initials: F
authors.lastname: Han
authors.affiliation: Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016, People's Republic of China.|University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing, 100049, People's Republic of China.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Optoelectronic Materials Chemical and Physics, Fujian Institute of Research on The Structure of Matter, Chinese Academy of Sciences, 155 Yangqiao Road West, Fuzhou, 350002, People's Republic of China.
authors.forename: Songquan
authors.initials: S
authors.lastname: Wu