激光合成b fesi2的结构特性及性能研究-study on structural characteristics and properties of laser synthesized b fesi _ 2.docxVIP

AbstractThermoelectric material is a semiconductor material that can realize the direct conversion between thermal energy and electric energy, so it can serve as a good solution to the environmental problems and energy problems currently faced by the world. β-FeSi2 thermoelectric material has a good performance in thermoelectric conversion in thetemperature range from 200℃ to 900℃, and its source material has such advantages ofbeing abundant, free of pollution to the environment and possessing high inoxidizability, therefore, it enjoys a good application prospect.However, since β-FeSi2 semiconductor material only has a narrow phase tranformation range, it can easily contain both ε-phase and α-phase at the same time, which will lead to an obvious decrease of its thermoelectric performance. In addition, grain refinement will increase its thermoelectric performance. Therefore, the excogitation of a processing technique that can realize the preparation of single-phase β-FeSi2 with refined grains is of great importance to its application. This thesis will study the processing technique of preparing β-FeSi2 by laser sintering, and the specific procedures are as follows:First, the mixed powder will be ball milled and then the power that has beenintensely and thoroughly mixed can be got, after which the power will be cold pressed into lumps for the convenience of sintering experiment. Then the lumps of power will be presintered in a tube vacuum furnace, in which process the sintering time and temperatures influence on the phase transformation of the alloy will be studied.Laser sintering is applied to prepare specimen according to its advantages of rapid heating rate and high cooling rate. In this thesis, laser sintering is applied for the first time for the preparation of β-FeSi2 material, and the sintering temperature field is simulated with the application of ANSYS in order to determine relatively good sintering parameters.The study on sintering will be launche