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Modeling the grain growth kinetics of doped nearly fully dense nanocrystalline ceramics
Affiliation:1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, Shaanxi 710072, PR China;2. Department of Materials Science & Engineering, University of California, Davis, CA 95616, USA;1. National Research Nuclear University MEPhI, Kashirskoye shosse 31, Moscow 115409, Russia;2. San Diego State University, 5500 Campanile Dr, 92182, San Diego, USA;1. Department of Physics, Changwon National University, Changwon, Gyeongnam 641-773, Republic of Korea;2. School of Nano and Advanced Materials Engineering, Changwon National University, Changwon, Gyeongnam 641-773, Republic of Korea;1. Department of Mechanical Engineering, Mount Zion College of Engineering and Technology, Pudukottai, Tamilnadu 622507, India;2. Department of Mechanical Engineering, Sri Venkateswara College of Engineering & Technology, Chittoor, Andhra Pradesh, 517127, India;1. Université de Limoges, IRCER, CNRS, UMR 7315, 12 Rue Atlantis, F-87000 Limoges, France;2. Université de Lorraine, CNRS, IJL, F-54000 Nancy, France;3. Safran Tech, Rue des Jeunes Bois, 78772 Magny Les Hameaux, France
Abstract:A grain growth model to describe dopant effects on nanocrystalline ceramics is proposed by incorporating the dopant-segregation-dependent grain boundary (GB) energy and the GB mobility subjected to intrinsic drag and pore drag (both affected by dopant segregation) into the parabolic growth formula. The model addresses the common case of residual porosity in grain growth behavior. Taking near-fully dense nanocrystalline lanthanum doped Yttria stabilized Zirconia (La doped YSZ) as the system of study, the grain growth behavior was explored using the model. The substantially suppressed grain growth in La doped YSZ as compared to La-free YSZ could be attributed to the combined effect of thermodynamically reduced GB energy and kinetically reduced GB mobility. Contrary to previous assumptions, the model suggests that, relative to the GB energy overall effect, the effect of the dopant on the GB mobility plays a more significant role in reducing coarsening. Furthermore, model calculation shows that both intrinsic drag and pore drag makes certain contribution to the evolution of GB mobility during the grain growth.
Keywords:Grain growth  Dopant  Segregation  YSZ
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