Nanoscale size effects in crystallization of metallic glass nanorods.
Atomistic understanding of crystallization in solids is incomplete due to the lack of appropriate materials and direct experimental tools. Metallic glasses possess simple metallic bonds and slow crystallization kinetics, making them suitable to study crystallization. Here, we investigate crystallization of metallic glass-forming liquids by in-situ heating metallic glass nanorods inside a transmission electron microscope. We unveil that the crystallization kinetics is affected by the nanorod diameter. With decreasing diameters, crystallization temperature decreases initially, exhibiting a minimum at a certain diameter, and then rapidly increases below that. This unusual crystallization kinetics is a consequence of multiple competing factors: increase in apparent viscosity, reduced nucleation probability and enhanced heterogeneous nucleation. The first two are verified by slowed grain growth and scatter in crystallization temperature with decreasing diameters. Our findings provide insight into relevant length scales in crystallization of supercooled metallic glasses, thus offering accurate processing conditions for predictable metallic glass nanomolding.
Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA.
Sungwoo
S
Sohn
Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA.|Energy Sciences Institute, Yale West Campus, West Haven, Connecticut 06516, USA.
Yeonwoong
Y
Jung
Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA.|Energy Sciences Institute, Yale West Campus, West Haven, Connecticut 06516, USA.
Yujun
Y
Xie
Department of Chemical &Environmental Engineering, Yale University, New Haven, Connecticut 06511, USA.
Chinedum
C
Osuji
Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA.
Jan
J
Schroers
Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA.|Energy Sciences Institute, Yale West Campus, West Haven, Connecticut 06516, USA.
Judy J
JJ
Cha