title: Amorphization and Directional Crystallization of Metals Confined in Carbon Nanotubes Investigated by in Situ Transmission Electron Microscopy.
abstract: The hollow core of a carbon nanotube (CNT) provides a unique opportunity to explore the physics, chemistry, biology, and metallurgy of different materials confined in such nanospace. Here, we investigate the nonequilibrium metallurgical processes taking place inside CNTs by in situ transmission electron microscopy using CNTs as nanoscale resistively heated crucibles having encapsulated metal nanowires/crystals in their channels. Because of nanometer size of the system and intimate contact between the CNTs and confined metals, an efficient heat transfer and high cooling rates (∼10(13) K/s) were achieved as a result of a flash bias pulse followed by system natural quenching, leading to the formation of disordered amorphous-like structures in iron, cobalt, and gold. An intermediate state between crystalline and amorphous phases was discovered, revealing a memory effect of local short-to-medium range order during these phase transitions. Furthermore, subsequent directional crystallization of an amorphous iron nanowire formed by this method was realized under controlled Joule heating. High-density crystalline defects were generated during crystallization due to a confinement effect from the CNT and severe plastic deformation involved.
authors.forename: Dai-Ming
authors.initials: DM
authors.lastname: Tang
authors.affiliation: §Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.|∥Division of Nuclear Materials Science and Engineering, and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Cui-Lan
authors.initials: CL
authors.lastname: Ren
authors.affiliation: ⊥Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Ruitao
authors.initials: R
authors.lastname: Lv
authors.affiliation: §Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.
authors.forename: Wan-Jing
authors.initials: WJ
authors.lastname: Yu
authors.affiliation: §Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.
authors.forename: Peng-Xiang
authors.initials: PX
authors.lastname: Hou
authors.forename: Ming-Sheng
authors.initials: MS
authors.lastname: Wang
authors.forename: Xianlong
authors.initials: X
authors.lastname: Wei
authors.forename: Zhi
authors.initials: Z
authors.lastname: Xu
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Kawamoto
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Bando
authors.forename: Masanori
authors.initials: M
authors.lastname: Mitome
authors.affiliation: §Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: §Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.
authors.forename: Hui-Ming
authors.initials: HM
authors.lastname: Cheng
authors.forename: Dmitri
authors.initials: D
authors.lastname: Golberg
keywords: In situ electron microscopy; amorphization; carbon nanotubes; molecular dynamics simulations; phase transition