Papers by Keyword: Monte Carlo Model

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Authors: Yu Niu, Feng Xu, Xiao Fang Hu, Yong Cun Li, Jing Zhao, Zhong Zhang
Abstract: A kinetic Potts Monte Carlo model was used to investigate the microstructural evolution of a three particles configuration during sintering. The a series of peculiar phenomena was observed and analyzed quantitatively, which indicated that even if the particle shape and the contact area are both completely symmetrical, the asymmetric neck growth will arise due to a special particle arrangement. Although the linear relationship between neck size logarithm and time logarithm was consistent with the traditional theory, a slower neck growth rate comparing with that of the two sphere model displayed a result of the asymmetric neck growth. The analysis of the particle rotation was made to confirm the occurrence of the asymmetric neck growth. It was firstly observed that the morphology of the grain boundaries became bevel, and the reason for this morphology was discussed. All the special phenomena have proved that the asymmetric particle arrangement about the contact area can trigger the unstable neck growth.
Authors: Jen Chieh Tsao, Chiung Chieh Su
Abstract: The radiometric temperature measurement is often applied to the in-situ and real-time monitor for rapid thermal processing of semiconductor wafer. To obtain good accuracy, the effective emissivity of measured spot is determined simultaneously as well. However, the effective emissivity strongly depends on the characteristics of wafer, processing chamber, and sensors. This paper presents a Monte Carlo model with bi-directional reflection distribution function to estimate the related effective emissivity of wafer. The ends of radiation thermometer considered are located either on the inner surface of processing chamber or at the proximity of wafer. The results are checked and compared with those of the previous work. Finally the primary effects on radiometric temperature measurement are analyzed and discussed.
Authors: Sheng Yu Wang, Anthony D. Rollett
Abstract: The subgrain structure of hot rolled aluminum alloy AA 5005 has been characterized on as-received samples using Electron Backscatter Diffraction (EBSD). Based on the OIM scans of RD-ND and TD-ND, 3 dimensional microstructures of subgrains are built up using the 3D Microstructure Builder, which is a method for developing statistically representative digital representations of microstructures. Following the generation of microstructure, different textures were fit to these reconstructed 3D microstructures, based on individual components such as Brass and S textures. For this study, the Brass texture was chosen as an exemplary case. Monte Carlo simulation was used to model subgrain coarsening and visualization was a key to detecting abnormal grain growth. The main objective is to understand the circumstances under which we can expect abnormal (sub-)grain growth to lead to nucleation of recrystallization.
Authors: Jie Zhou, Tian Rui Zhou
Abstract: The deformation ability of metals and the mechanic characteristics of metal parts are closely related to the material’s microstructure and grain size, so it’s important to study the simulation techniques of microstructure evolution. Common microstructure simulation techniques include digital simulation and graphic simulation. This paper firstly introduced the simulation techniques of microstructure, and then focused on the graphic simulation technique that can directly show grain boundary network’s evolution process. It then built a Monte Carlo model of the grain growth during super plastic deformation, and implemented the graphic illustration of grain growth using Visual Studio software. The result matched well with the experimental outcome, which proved the usability of the technique
Authors: Krystian Piękoś, Jacek Tarasiuk, Krzysztof Wierzbanowski, Brigitte Bacroix
Abstract: The generalized deterministic vertex model was successfully used to study the recrystallization process and the corresponding results were published elsewhere [1]. In its classical form the vertex model has analytical formulation, basing on the total energy (i.e. boundary energy and stored energy) minimization. A change of grain boundary configuration in classical vertex model is found by the calculation of vertex velocities. Consequently, a global and complex system of equations has to be solved in each step. In order to simplify calculations and to handle the problem in a more flexible way, the statistical model was proposed. Typical elements of Monte Carlo algorithm were incorporated into the vertex model: a random (and small) modification of microstructure is accepted with the probability proportional to Boltzmann factor. This approach is closer to the stochastic nature of recrystallization process. The model was used to study the recrystallization of 70% and 90% cold rolled polycrystalline copper. It predicts correctly recrystallization textures for high and low strains.
Authors: Yu Hong Zhao, Yue Zhang, Da Hai Zhang
Abstract: Based on the Potts model, the grain growth of Si3N4 in liquid phase sintering process was simulated by Monte-Carlo method. A two-dimensional, square lattice is used to digitize the microstructure and the components and grain orientation are distributed randomly. The periodical boundary condition is applied. In the initial simulation, the grain growth and coarsening process driven by the reduction in interfacial free energy within a complex system involving a liquid phase were investigated with 32 orientations and different fraction of a liquid phase has been considered. Simulation was carried out with 200×200 lattice. The effects of the liquid amount on the grain growth mechanism and microstructures were discussed.
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