A new understanding of grain boundaries
City University of Hong Kong researchers, collaborating with international experts, have gained new insights into the nature of grain boundaries in crystalline materials.
Grain boundaries, which are defects where crystals with different orientations meet, significantly affect a material's mechanical and physical properties. Traditionally, the migration or movement of these boundaries was thought to be directly proportional to a constant mobility factor.
Grain boundaries, which are defects where crystals with different orientations meet, significantly affect a material's mechanical and physical properties.
However, the new study, led by Dr Han Jian of City University used both simulations and in situ experiments to reveal that this mobility is direction-dependent in non-symmetric grain boundaries. This means grain boundaries can move in one direction without an external driving force, resembling a concept known as the Brownian ratchet, where random atomic movements result in directional motion.
This discovery was recently published in Science, with Caihao Qiu listed as the first author and Han as a corresponding author, along with Dr Marco Salvalaglio from the Dresden University of Technology, Professor Xiaoqing Pan from the University of California, Irvine, and Professor David J. Srolovitz from the University of Hong Kong.
The study suggests new methods for manipulating material microstructures, potentially impacting materials science significantly. For example, if grain boundaries can be manipulated to move in desired directions without a constant net driving force, this might lead to more energy-efficient material processing methods.