Thermodynamic variational principle, its connections to the phenomenological laws and its applications to the derivation of microstructural models
报告人：Qiang Du（SINTEF Materials and Chemistry）
地点：Room 1114, Sciences Building No. 1
Abstract: Understanding microstructural evolution occupies a central position in the discipline of materials science and engineering. Microstructural evolution involves complex, coupled and often non-linear processes, even the description of the dynamics for isolated microstructural evolution processes can be quite complicated. This is in great contrast with the simplicity of the mathematical tools behind microstructural evolution theories, which, built upon empirical experimental data, often draw heavily on the linear phenomenological laws. It would be desirable to enrich the microstructural evolution theory by introducing a powerful mathematical tool, which could enable describing and predicting the rich intertwining phenomena such as diffusive or displacive phase transformation, grain growth, generation or annihilation of defects (vacancy, dislocations, etc) in a straightforward manner. Of course there have been continuing efforts along this front and I will restrict myself to some issues in the development and application of the thermodynamic variational principle. I will try to draw attentions to some "seemingly forgotten" papers and provide our understanding and viewpoints on some debates. It is our opinions that the first appealing feature about the thermodynamic extremum principle in materials science is the nature that it could give approximate solutions with tunable accuracy. The second appealing feature is its role as a basic principle in deriving the new models such as phase field and phase field crystal. It is hoped that my talk could promote the development and application of the variational principle even further in materials science.