Ti+CNTs强化NiAl基复合材料的微观组织与性能

Microstructure and properties of TiC-CNTs reinforced NiAl matrix composite

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。

Microstructure and properties of TiC-CNTs reinforced NiAl matrix composite fabricated via self-propagating high-temperature synthesis（SHS） method were investigated.The phase constitution,composition,microstructure and its forming mechanisms of the composites were examined.The results show that the composites are mainly composed of NiAl,TiC and a small amount of residual CNTs.The CNTs as carbon sources and nuclei react with Ti to forming TiC.The morphology of TiC presents particles or thin films around the CNTs.Increasing the content of Ti and CNTs,the TiC particles grow up and are homogeneously distributed in the NiAl matrix.With the adding of Ti and CNTs,the size of NiAl grains is greatly refined,and the compressive strength and microhardness of the composites is enhanced by the in situ synthesis of TiC particles.Fracture toughness of the composites is increased due to the reinforcements of the TiC particles and CNTs fibers by the synergistic strengthening mechanisms of crack deflection and fiber pull-out.