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采用XRD、OM和TEM等方法对原位合成Ti_2AlN/Ti-48Al-2Cr-2Nb复合材料在900°C时效过程中的组织稳定性进行研究,并与未增强的Ti-48Al-2Cr-2Nb合金进行对比分析。研究结果发现,在TiAl合金中,α_2片层变细并发生破碎,且随着时效时间的延长变得不连续。以α_2板条平行分解和破碎为特征的α_2片层向g的分解导致片层结构退化。而在复合材料中,在900°C时效100 h,片层结构保持相对稳定。除了片层平行分解和细小的氮化物沉淀外,没有发现α_2片层破碎。复合材料较好的组织稳定性主要与α_2/γ界面上的Ti_2AlN颗粒沉淀有关。Ti_2AlN相的析出对延缓复合材料基体片层组织粗化具有重要作用。
The microstructure and mechanical properties of Ti_2AlN / Ti-48Al-2Cr-2Nb composites during aging at 900 ° C were investigated by XRD, OM and TEM. For comparative analysis. The results show that, in the TiAl alloy, α_2 sheet thinner and broken, and with the aging time becomes discontinuous. The decomposition of α_2 sheet characterized by the parallel decomposition and fragmentation of α_2 sheet leads to the degeneration of sheet structure. In the composites, the sheet structure remained relatively stable at 900 ° C for 100 h. In addition to the parallel decomposition of the sheet and the fine precipitation of the nitride, no disintegration of the α_2 sheet was found. The better tissue stability of composites is mainly related to the precipitation of Ti 2 AlN particles on α 2 / γ interface. The precipitation of Ti 2 AlN phase plays an important role in retarding the coarsening of the matrix of the composite matrix.