用熔体直接反应法在不同起始反应温度下制备了TiB2/Al复合材料,并进行了重熔处理,用光学显微镜、扫描电镜、透射电镜等对复合材料的组织和力学性能进行了测试分析,并探讨了熔体中的反应机制.结果表明:提高起始反应温度可提高复合材料中TiB2颗粒含量及分布均匀性;重熔处理对复合材料中颗粒分布影响较小,850℃制备的复合材料在750℃重熔后的抗拉强度和伸长率分别达到181.2 MPa和22.5%;制备TiB2/Al复合材料时,混合粉中的TiO2、KBF4首先与铝熔体反应,反应过程中可能存在中间相AlB2和TiAl3,但随着反应的进行,自由能较高的AlB2和TiAl3将分解形成自由能更低的TiB2.
The TiB2/Al composites were fabricated by direct reaction method at different initial reaction temperatures, and the remelting process was carried on. The microstructure and mehanical properties of composites were analyzed by means of OM, SEM and TEM. The reactive mechanism in the melt was also studied. The results show that the volume percent of TiB2 increased and its distribution improved as increase of initial reaction temperature. It seemed to be little effect on the distribution of TiB2 particles for the remelting treatment. The tensile strength and elongation were 181.2 MPa and 22. 5% respectively for the composites remelted at 750 ℃ after fabricated at 850 ℃. In the process of TiB2/Al composite preparation, TiO2 and KBF4 in the mixed powder reactedwith Al melt firstly. There might be mesophase AlB2 and TiAl3 appeared during the reaction. With the reaction progressing, AlB2 and TiAl3 with high free energy would decompose to TiB2 with lower free energy.
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