气体雾化法制备TiB_(2)/Al复合材料粉末及其组织演变

Preparation and microstructure evolution of TiB_(2)/Al composite powders by gas atomization method

采用氟盐反应法制备TiB_(2)/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TiB_(2)/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TiB_(2)的溶度积远小于TiAl_(3)和AlB_(2)的溶度积,TiB_(2)自Al熔体中沉淀析出导致的体系Gibbs自由能变化量比TiAl_(3)或AlB_(2)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。TiB_(2)/Al复合材料铸锭及粉末均主要由α-Al相和TiB_(2)相组成。气体雾化制备TiB_(2)/Al复合材料粉末中TiB_(2)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。TiB_(2)/Al复合材料粉末的粒度主要分布在10~100μm之间,呈正态分布,粒径介于10~70μm粉末占比(质量分数)约为81.1%,粒径大于70μm粉末收得率为12.6%,粒径小于10μm粉末收得率为6.3%。

The TiB_(2)/Al composite ingot was prepared by the fluoride salt reaction method,and the TiB_(2)/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 TiB_(2) in Al melt is much smaller than that of the TiAl_(3) and AlB_(2) phases in the experiment condition,the change of Gibbs free energy caused by the precipitation of TiB_(2) from Al melt is more negative than that caused by the precipitation of TiAl_(3) or AlB_(2) from Al melt.The TiB_(2)/Al composite ingot and powders are mainly composed of α-Al matrix and TiB_(2) phase.The TiB_(2) particles in the TiB_(2)/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 TiB_(2)/Al composite powders exhibits a normal state in the range of 10~100μm.The powder yield with the particle size between 10~70μm is 81.1%,the yield for the particle larger than 70μm is 12.6%,and that less than 10μm is 6.3%.