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Title: Testing thermal gradient driving force for grain boundary migration using molecular dynamics simulations

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 85; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-05-18 09:11:22; Journal ID: ISSN 1359-6454
Country of Publication:
United States

Citation Formats

Bai, Xian-Ming, Zhang, Yongfeng, and Tonks, Michael R. Testing thermal gradient driving force for grain boundary migration using molecular dynamics simulations. United States: N. p., 2015. Web. doi:10.1016/j.actamat.2014.11.019.
Bai, Xian-Ming, Zhang, Yongfeng, & Tonks, Michael R. Testing thermal gradient driving force for grain boundary migration using molecular dynamics simulations. United States. doi:10.1016/j.actamat.2014.11.019.
Bai, Xian-Ming, Zhang, Yongfeng, and Tonks, Michael R. 2015. "Testing thermal gradient driving force for grain boundary migration using molecular dynamics simulations". United States. doi:10.1016/j.actamat.2014.11.019.
title = {Testing thermal gradient driving force for grain boundary migration using molecular dynamics simulations},
author = {Bai, Xian-Ming and Zhang, Yongfeng and Tonks, Michael R.},
abstractNote = {},
doi = {10.1016/j.actamat.2014.11.019},
journal = {Acta Materialia},
number = C,
volume = 85,
place = {United States},
year = 2015,
month = 2

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.actamat.2014.11.019

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Cited by: 6works
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  • Strong thermal gradients in low-thermal-conductivity ceramics may drive extended defects, such as grain boundaries and voids, to migrate in preferential directions. In this work, molecular dynamics simulations are conducted to study thermal gradient driven grain boundary migration and to verify a previously proposed thermal gradient driving force equation, using uranium dioxide as a model system. It is found that a thermal gradient drives grain boundaries to migrate up the gradient and the migration velocity increases under a constant gradient owing to the increase in mobility with temperature. Different grain boundaries migrate at very different rates due to their different intrinsicmore » mobilities. The extracted mobilities from the thermal gradient driven simulations are compared with those calculated from two other well-established methods and good agreement between the three different methods is found, demonstrating that the theoretical equation of the thermal gradient driving force is valid, although a correction of one input parameter should be made. The discrepancy in the grain boundary mobilities between modeling and experiments is also discussed.« less
  • The diffusion induced grain boundary migration (DIGM) has been studied in the Ni(Cu) system over the temperature range 723--1,023 K using light microscopy, scanning electron microscopy and electron probe microanalysis (EPMA). Four different stages of the grain boundary (GB) migration during DIGM were found, involving nucleation, initial, stationary and mixed stages. During the mixed stage the DIGM process occurs simultaneously with the diffusion induced recrystallization, and it is impossible to separate the two phenomena. The EPMA measurements reveal that the Cu concentration in the DIGM zone does not remain constant, but increases with increasing annealing time. The highest Cu concentrationmore » which does not depend on annealing conditions is situated in the middle of the DIGM zones. Based on the measured Cu distribution in the DIGM zones, the coherency strain driving force for GB migration is calculated. In some cases the calculated values are lower than the energy difference across the GB due to its curvature. It is concluded that some other driving force should be involved. The nucleation and initial stages of the DIGM process can be explained by a model based on the diffusion induced GB stresses. The Arrhenius parameters of the diffusion along and across the GB in Ni-rich Ni-Cu alloys have been determined.« less
  • Electromigration in thin metal films leads to internal stresses. Elastic crystal anisotropy may cause a distinct gradient of these stresses across the grain boundary if the adjacent grains have different orientations relative to the grain boundary and to the substrate. The stress gradient gives rise to a driving force for grain boundary migration. This driving force is proportional to the crystal anisotropy parameter and to the dilatation caused by electromigration. At typical values of the parameters the driving force is comparable to the driving force caused by the curvature when the radius of curvature is about 10{micro}m. The anisotropy drivingmore » force may cause low temperature recrystallization, especially in the regions where internal stresses are about the threshold value, or exceed it, and it may lead to an increase in the number of symmetrical grain boundaries during electromigration in the near-anode zone of interconnect lines.« less
  • A large number of experimental studies have been carried out on diffusion induced grain boundary migration (DIGM) and diffusion induced recrystallization (DIR) in binary alloy systems. A region with different composition is left behind a moving grain boundary (GB) owing to GB migration combined with the diffusion of solute atoms along the moving boundary in DIGM. On the other hand, during DIR, new grains with different solute concentrations are produced behind moving GBs due to recrystallization combined with diffusion of solute atoms along the moving GBs. The compositional discontinuity between the regions ahead and behind the moving GB should bemore » the most important driving force for DIGM and DIR. The driving force due to this compositional discontinuity is usually called chemical driving force. Hillert and Purdy proposed the chemical driving force model for DIGM during alloying in binary systems. However, there are several sinks for the chemical driving force. For instance, if the migration of a GB is slow enough, solute atoms will penetrate into the untransformed matrix ahead of the moving GB and such a process may consume all the driving force. This can be avoided by coherency stresses building up in the penetration zone due to the composition dependence of the lattice parameter of the matrix. A new model has been proposed to evaluate the driving force for DIGM and DIR during alloying in binary systems as a function of the migration rate on the basis of the idea in a previous paper. Although this model is applicable to both DIGM and DIR, attention will be focused on DIGM to simplify the description in this paper.« less