自发熔渗法制备TiC/NiAl复合材料和其微观组织特征

PRESSURELESS MELT INFILTRATION PROCESSING AND THE MICROSTRUCTURAL CHARACTERISTICS OF TiC/NiAl COMPOSITES

  • 摘要: 用自发熔化渗透法制备高TiC含量 (~75vol%) 的TiC/NiAl复合材料,研究了渗透温度和渗透时间对TiC/NiAl复合材料微观组织形成、硬度及断裂性能的影响。采用XRD 和TEM/EDS分析了复合材料的相组成、微观结构和NiAl相与TiC颗粒在高温渗透过程中的互溶情况。结果表明:自发熔渗法是制备致密的TiC/NiAl复合材料的有效方法,适当提高渗透温度,可大大缩短渗透时间。在完成渗透获得致密组织的前提下,渗透温度和渗透时间对TiC/NiAl复合材料的硬度及断裂韧性无显著影响。NiAl相和TiC颗粒结合良好,是渗透后复合物的仅有组成相。TiC少量地溶于NiAl,溶解度随渗透时间增长而增大,且在TiC颗粒外层,发现有少量的Al和微量的Ni。

     

    Abstract: Pressureless melt infiltration was used for preparing high TiC content TiC/NiAl composites. Effects of the infiltration temperature and time on the microstructure, hardness and fracture toughness of the composites were studied. XRD and EDS/TEM were used to analyze the phase identification and the solubility of NiAl and TiC in each other. The results show that pressureless melt infiltration is an effective method to fabricate dense TiC/NiAl composites. The infiltration time can greatly decrease when the infiltration temperature suitably increases. No obvious effect of the infiltration temperature and time on the hardness and the fracture toughness of the composites was found. NiAl and TiC were well bonded, and they are the only two phases in the composites after infiltration. TiC partially dissolved into NiAl phase, and the solubility increased with increasing infiltration time. Little Al and a trace of Ni were detected at the outer layer of TiC.

     

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