| Microwave sintering is a novel rapid alloy preparation technique, the microstructure of alloy would become more refined by microwave sintering, which would enhance the mechanical properties of the materials. The study of related mechanics mechanism of microwave sintering is very important for the fundamental research and the industrial production. It is important to study the mechanics mechanism during microwave sintering, because it is the key way for in-depth understanding of the mechanism of microwave sintering alloys, and it was the critical path for controlling microwave preparation of alloys. In order to analyze and verify the presence of mechanics mechanism during microwave sintering process, microwave sintering of metal with different electromagnetic properties were carried out, SR-CT technology was used for the online observation, analysis of the sintering parameters were carried out. The main content and the innovation of this paper are:1. It was the first time to carry out online microwave sintering study of metal with different electromagnetic properties, rapid and specific phenomenon of the metal microstructure evolution was observed, analysis of the relevant material diffusion mechanism was carried out.Microwave sintering of metal with different electrical properties (Al, Ti and Al-Ti mixed metal) and metals with different magnetic properties (Cu, Ni and Cu-Ni mixed metal) was carried out, SR-CT technology was used for the online observation. By the three-dimensional images obtained by SR-CT experiment, different metal microstructure evolutions during microwave sintering were found. Quantitative analysis of key parameters was carried out, sintering characteristics of different metal systems was proposed.2. The influence of eddy currents on the microstructure changes was clarified, study on the force and thermal effects caused by the eddy currents was carried out, and relevant mechanism was analyzed combined with improved phase field model.The intensity of metal eddy currents caused by the microwave electromagnetic field was analyzed, the model of the mechanical effects was constructed, the model was introduced in the phase field model, the reason for the difference of sintering neck growth between Al and Ti was found. The diffusion coefficient was changed by the heating effect of eddy current. The diffusion coefficient of the phase field model was changed into variable, which verified the influence of the thermal effects of eddy currents.3. The force and thermal effect caused by the magnetic domain and the interface of mixed metal was discussed.By the microstructure growth curve of ferromagnetic metal Ni, the driving force caused by the interaction between magnetic domain structure and magnetic field was found, the diffusion rate was accelerated by the driving force, which leaded to the faster microstructure evolution, enhanced diffusion mechanisms was introduced into phase-field model to verify the correctness of the conclusion.In this paper, SR-CT online study about microwave sintering of metals with different electromagnetic properties was carried out. According to the characteristics of microstructure evolution, the thermal and mechanical effects between microwave and metal were analyzed, the conclusion was verified by the improved phase field model. |
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