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以Ni、Al、Ti以及碳纳米管(CNTs)为原料,采用自蔓延高温合成(SHS)方法制备出含CNTs-TiC增强相的NiAl基复合材料;分析复合材料的物相组成、微观结构及成分分布,并探讨微观组织的形成机制。结果表明:合成产物主要为NiAl和TiC及少量未反应的CNTs;在Ni+Al体系中加入少量Ti+CNTs时,CNTs作为碳源和形核中心与Ti原子结合生成TiC颗粒,在CNTs周围形成尺寸细小的TiC颗粒或TiC薄层,当加入的Ti+CNTs含量增加时,TiC颗粒充分长大,呈现八面体或立方体形态,一部分弥散分布在NiAl基体中,一部分在NiAl晶界处团聚;随着Ti+CNTs的加入,NiAl晶粒得到显著细化,原位合成的TiC颗粒增强了复合材料的显微硬度和抗压强度,CNTs作为增强纤维,通过裂纹桥联及纤维拔出等机制强化材料的断裂韧性,CNTs-TiC的复合强化对材料起到增强增韧作用。
NiAl-based composites with CNTs-TiC reinforcing phase were prepared by SHS method using Ni, Al, Ti and CNTs as raw materials. The phase composition, microstructure, Composition distribution, and explore the formation mechanism of microstructure. The results show that NiAl and TiC and a few unreacted CNTs are the main products of the synthesis. When a small amount of Ti + CNTs is added to the Ni + Al system, CNTs acts as a carbon source and combines with the Ti atom to form TiC particles and forms around the CNTs When the content of Ti + CNTs increases, the TiC particles fully grow and appear octahedron or cube shape, some are dispersed in the NiAl matrix, and some are agglomerated in the NiAl grain boundaries. With the increase of Ti + CNTs content, With the addition of Ti + CNTs, the NiAl grains were significantly refined. The TiC particles synthesized in situ enhanced the microhardness and compressive strength of the composites. CNTs, as reinforcing fibers, were strengthened by crack bridging and fiber pull-out The fracture toughness of the material, CNTs-TiC composite strengthening play a role in strengthening and toughening the material.