First-principles calculation of grain boundary energy and grain boundary excess free volume in aluminum: role of grain boundary elastic energy
We examined the grain boundary energy (GBE) and grain boundary excess free volume (BFV) by applying the first-principles calculation for six  symmetric tilt grain boundaries in aluminum to clarify the origin of GBE. The GBE increased linearly as BFV increased. The elastic energy associated with BFV, namely the grain boundary elastic energy, was estimated as a function of BFV and the shear modulus. The grain boundary elastic energies were close in value to the GBEs. The charge density distributions indicated that the bonding in the grain boundary region is significantly different from the bonding in the bulk. The grain boundary elastic energies were 15–32% higher than the GBEs. This overestimation of the grain boundary elastic energy is caused by the characteristics of the electronic bonding at the grain boundary, which is different from bonding in the bulk. We have concluded that GBE results mainly from the grain boundary elastic energy.
KeywordsElastic Energy Generalize Gradient Approximation Local Density Approximation Boundary Plane Coincidence Site Lattice
The authors are grateful to Mr. Yasuhiko Inoue and Mr. Yuuki Nishiie, who were students in the department, for their assistance with the computations. This study was partly supported by a Giant-in-Aid for scientific Research on the Priority Area “Giant Straining Process for Advanced Materials Containing Ultra-High Density Lattice Defects” from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) and by the Light Metal Educational Foundation Inc. The authors thank Dr. Masanori Kohyama for useful discussion.
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