SPS合成碳纳米管增强Nb/Nb_5Si_3复合材料的组织和性能

Microstructure and Properties of Nb/Nb_5Si_3 Composites Strengthened with CNTs by Spark Plasma Sintering

采用放电等离子烧结法(SPS)原位合成了多壁碳纳米管(CNTS)增强Nb/Nb_5Si_3复合材料,研究了不同含量的碳纳米管对Nb/Nb_5Si_3复合材料的组织和性能的影响。研究表明:Nb/Nb5Si3复合材料的相组成主要为Nb、α-Nb_5Si_3和γ-Nb5_Si_3,当CNTS加入量达到2%(质量分数)时开始出现了新相Nb_4C_3。复合材料的力学性能(抗压缩强度、断裂韧性)随着碳纳米管含量的增加而增加,加入2%CNTs时达到最大值,抗压缩强度和断裂韧性提高幅度分别达到56%、31%;随后加入3%CNTs时,抗压缩强度和断裂韧性都有所降低。复合材料断口的扫描电镜照片表明,复合材料的断裂模式主要为脆性解理断裂并有部分沿晶断裂,复合材料的增韧化作用主要是由于碳纳米管的拔出效应和桥联机制。

The Nb/Nb_5 Si_3 in-situ composite material strengthened with multi-walled CNTs was prepared by Spark Plasma Sintering（SPS）.The effects of CNTs content on microstructure and properties of Nb/Nb_5 Si_3 in situ composites were investigated. The results show that the composites are composed of Nb,α-Nb_5 Si_3,and y-Nb5 Si3 phase. When the addition of CNTs reaches 2 wt%,a new phase Nb_4 C_3 is formed in the composites. The compressive strength and fracture toughness of the composites increase obviously with the increase of CNTs content. When the addition of CNTs is 2 wt%, the compressive strength and fracture toughness reach the maximum values, which increase by 56% and 31%, respectively. When the CNTs content is 3 wt%, the compressive strength and fracture toughness decrease. SEM fracture images show that the fracture appearance of the composites consists of brittle cleavage fracture and partial intercrystalline fracture. The toughening mechanisms of composites are mainly due to pull-out and bridging of the CNTs.