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气体雾化法制备TiB2/Al复合材料粉末及其组织演变

Preparation and microstructure evolution of TiB2/Al composite powders by gas atomization method

  • 摘要: 采用氟盐反应法制备TiB2/Al复合材料铸锭,并以此为原料利用高压气体雾化制粉技术制备TiB2/Al复合材料粉末。利用金相显微镜、扫描电子显微镜、X射线衍射仪、粒度分布仪等手段对所制备铸锭和粉末的组织及性能进行了表征。结果表明:Al熔体中TiB2的溶度积远小于TiAl3和AlB2的溶度积,TiB2自Al熔体中沉淀析出导致的体系Gibbs自由能变化量比TiAl3或AlB2自Al熔体中沉淀析出导致的体系Gibbs自由能变化量的值更小。TiB2/Al复合材料铸锭及粉末均主要由α-Al相和TiB2相组成。气体雾化制备TiB2/Al复合材料粉末中TiB2颗粒具有纳米尺度,且均匀弥散地分布于Al基体之中,不存在明显的偏聚现象。TiB2/Al复合材料粉末的粒度主要分布在10~100 μm之间,呈正态分布,粒径介于10~70 μm粉末占比(质量分数)约为81.1%,粒径大于70 μm粉末收得率为12.6%,粒径小于10 μm粉末收得率为6.3%。

     

    Abstract: The TiB2/Al composite ingot was prepared by the fluoride salt reaction method, and the TiB2/Al composite powders were prepared by the high pressure gas atomization. The structures and properties of the composite ingot and powders were characterized by metallographic microscope, scanning electron microscope, X-ray diffractometer, and particle size distribution instrument. The results demonstrate that, the solubility product of TiB2 in Al melt is much smaller than that of the TiAl3 and AlB2 phases in the experiment condition, the change of Gibbs free energy caused by the precipitation of TiB2 from Al melt is more negative than that caused by the precipitation of TiAl3 or AlB2 from Al melt. The TiB2/Al composite ingot and powders are mainly composed of α-Al matrix and TiB2 phase. The TiB2 particles in the TiB2/Al composite powders prepared by gas atomization have nano-scale, and uniformly disperse in the Al matrix, no obvious segregation phenomenon is observed. The size distribution of the TiB2/Al composite powders exhibits a normal state in the range of 10~100 μm. The powder yield with the particle size between 10~70 μm is 81.1%, the yield for the particle larger than 70 μm is 12.6%, and that less than 10 μm is 6.3%.

     

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