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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Melting temperature: from nanocrystalline to amorphous phase.
Shifang Xiao1, Wangyu Hu, Jianyu Yang
1Department of Applied Physics, Hunan University, Changsha 410082, People's Republic of China. shifangxiao@yahoo.com.cn
The Journal of Chemical Physics
|November 23, 2006
Summary
Nanocrystal melting temperatures decrease with size, then plateau as grain boundaries dominate. Amorphous phases exhibit significantly lower transformation temperatures due to structural differences.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Nanocrystals exhibit unique properties influenced by grain size.
- Melting temperature is a critical property affected by nanoscale phenomena.
- Understanding phase transitions in nanomaterials is crucial for applications.
Purpose of the Study:
- To investigate the relationship between nanocrystal grain size and melting temperature.
- To explore the transition from nanocrystalline to amorphous phases.
- To compare the thermal stability of nanocrystalline and amorphous silver (Ag).
Main Methods:
- Utilized Voronoi construction to extrapolate nanocrystal grain size to an infinitesimal value, forming an amorphous phase.
- Employed molecular dynamics simulations to study melting temperature variations.
- Analyzed the influence of grain size and grain boundaries on melting behavior.
Main Results:
- Identified two distinct regions for nanocrystal melting temperature dependence on grain size.
- Observed a decrease in melting temperature with decreasing grain size above ~4 nm for Ag.
- Found that melting temperature plateaus at smaller grain sizes due to dominant grain boundary effects.
- Demonstrated that the amorphous phase has a substantially lower solid-to-liquid transformation temperature than nanocrystals.
Conclusions:
- Grain boundary effects become dominant over grain phase effects in determining melting temperature at very small nanocrystal sizes.
- The structural differences between nanocrystalline and amorphous phases lead to distinct thermal transformation behaviors.
- This study provides insights into the phase stability and melting phenomena of nanomaterials.
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