小平面相/非小平面相共晶的亚快速定向凝固特性与性能研究

项目名称： 小平面相/非小平面相共晶的亚快速定向凝固特性与性能研究

项目编号： No.51201121

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 金属材料学科

项目作者： 崔春娟

作者单位： 西安建筑科技大学

项目金额： 25万元

中文摘要： 针对Ni3Si金属间化合物低的延展性、低的断裂韧性以及较差的高温抗蠕变性能等问题,本项目拟采用电子束悬浮区熔定向凝固技术，选择高延展性金属Ni做基体相，通过共晶反应获得Ni-Ni3Si共晶自生复合材料，从而使材料的综合力学性能得到改善。通过精确控制和优化定向凝固过程，制取组织超细化、体积分数可调且取向精度高的Ni-Ni3Si共晶自生复合材料，探明Ni-Ni3Si共晶的亚快速定向凝固组织特征，揭示不同凝固速率时固液界面的演化规律，明确相界面微观结构及晶体学位向关系，阐明小平面相/非小平面相的共生机制，建立小平面相/非小平面相共晶的定向凝固理论模型。在此基础上，考察Ni-Ni3Si共晶的高温力学性能，建立凝固工艺参数-凝固组织-材料性能之间的关系。这不仅为采用高梯度亚快速定向凝固技术制备高温结构材料的研究和实践提供技术支撑，而且对于丰富和发展共晶凝固理论也有重要的学术价值。

中文关键词： 定向凝固；共晶自生复合材料；固液界面；小平面相；力学性能

英文摘要： Aiming at the poor ductility at ambient temperatures and the bad fabricability at high temperatures of the Ni3Si intermetallic compound, the electron beam floating zone melting technique is adopted to prepare the Ni-Ni3Si eutectic in situ composite by eutectic reaction, and the mechanical properties of the Ni3Si intermetallic compound can be improved on account of combining with Ni matrix. High-aligned and uniformly-distributed Ni3Si in the Ni matrix can be obtained by controlling the the directional solidification process. Microstructure of the Ni-Ni3Si eutectic in situ composites at sub-high solidification rates are studied in detail, the evolvement rule of solid/liquid interface can be indicated, the structure of the phase interface and the preferred orientation can be explicited by HRTEM, the growth mechanism of the faceted phase/non-faceted phase eutectic can be explained, and the theoretical model of the facted/non-faceted eutectic solidification can be established. Moreover, the relationship among solidification parameters, microstructures and properties can be achieved eventually. The present study can not only provide the technique support for the preparation of the high temperature structural materials, but also enrich and develop the eutectic solidification theory.

英文关键词： Directional solidification；Eutectic in situ composite；Solid/liquid interface；Faceted phase；Mechanical properties