Wan Qiong, Li Fuguo, Wang Wenjing, Hou Junhua, Cui Wanyue, Li Yongsheng
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China.
College of Material Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China.
Materials (Basel). 2019 Jun 19;12(12):1967. doi: 10.3390/ma12121967.
In this study, ball-milled powder of Ti and Al was used to fabricate Ti-Al intermetallic compound-reinforced Al matrix composites by an in-situ reaction in cold-pressing sintering and hot-pressing sintering processes. The detailed microstructure of the Ti-Al intermetallic compound-reinforced Al composite was characterized by optical microscopy (OM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), and electron backscattered diffraction (EBSD). The results indicate that a typical core-shell-like structure forms in the reinforced particles. The shell is composed of a series of Ti-Al intermetallic compounds and has good bonding strength and compatibility with the Al matrix and Ti core. With cold-pressing sintering, the shell around the Ti core is closed, and the shell thickness increases as the milling time and holding time increase. With hot-pressing sintering, some radiating cracks emerge in the shell structure and provide paths for further diffusion of Ti and Al atoms. The Kirkendall effect, which is caused by the difference between the diffusion coefficients of Ti and Al, results in the formation of cavities and a reduction in density degree. When the quantity of the intermetallic compounds increases, the hardness of the composites increases and the plasticity decreases. Therefore, factors that affect the quantity of the reinforcements, such as the milling time and holding time, should be determined carefully to improve the comprehensive properties of the composites.
在本研究中，采用Ti和Al的球磨粉末，通过冷压烧结和热压烧结过程中的原位反应制备Ti-Al金属间化合物增强铝基复合材料。利用光学显微镜（OM）、X射线衍射（XRD）、能谱分析（EDS）和电子背散射衍射（EBSD）对Ti-Al金属间化合物增强铝基复合材料的微观结构进行了详细表征。结果表明，增强颗粒中形成了典型的核壳状结构。壳层由一系列Ti-Al金属间化合物组成，与Al基体和Ti核具有良好的结合强度和相容性。在冷压烧结过程中，Ti核周围的壳层是封闭的，壳层厚度随着球磨时间和保温时间的增加而增加。在热压烧结过程中，壳层结构中出现一些放射状裂纹，为Ti和Al原子的进一步扩散提供了路径。由Ti和Al扩散系数差异引起的柯肯达尔效应导致空洞的形成和密度降低。当金属间化合物的数量增加时，复合材料的硬度增加而塑性降低。因此，应仔细确定影响增强体数量的因素，如球磨时间和保温时间，以提高复合材料的综合性能。
