氩气雾化TiAl合金粉末特性及雾化机理研究

TiAl alloy represents a new class of light-weight structural materials for use at high temperature, the powder metallurgy route offers an attractive alternative to the ingot rout for the preparation of TiAl alloy especially of TiAl sheet. The TiAl alloy powder was fabricated by cold wall induction crucible melting and gas atomization techniques, the basic feature of gas flow field, the influences of operation parameters as atomization pressure and melt superheat on the atomization process, as well as the powder particle size and microstructure, were investigated, and the multi-phase fluid simulation was analyed to evaluate the breakup mechanism during atomizing process; the properties and defects of TiAl powder were studied, the subject is to break through the oxygen controling technology, to surpply the foundation of development of TiAl alloy powder processing and meet the requirements of high performance light structural materials for high-temperature applications in aerospace and other areas.

TiAl合金是一种新型的轻质高温结构材料，在航空航天和汽车发动机等领域有广阔的应用前景，粉末冶金方法可以消除铸造缺陷，有望实现TiAl合金尤其是TiAl合金板材的工程化应用。本课题采用冷壁坩埚感应熔炼装置氩气雾化法制备纯净的TiAl合金粉末，在冷壁坩埚熔炼工艺和雾化技术研究基础上，对雾化过程中金属液滴与雾化气体的相互作用进行分析，通过气体流场和液体流场的两相流计算，研究雾化压力、熔体过热度等对金属液雾化作用规律，以及对粉末的尺寸和微观结构的影响，明确雾化工艺参数与粉末特性的关系，通过对TiAl合金粉末筛分储存等后续处理技术的研究，进行粉末特性和粉末缺陷的分析研究，突破活性粉末氧含量控制技术，为改进TiAl合金粉末的制备工艺提供科学依据，同时为高性能轻质粉末高温结构材料的研制奠定坚实的理论和试验基础，满足航空航天等领域的重大需求。

本项目采用冷壁坩埚感应熔炼氩气雾化法制备纯净的TiAl合金粉末，对雾化过程中金属液滴与雾化气体的相互作用进行了分析，在两相流流动和雾化喷嘴气体动力学研究基础上，结合Fluent软件的数值模拟，研究了TiAl液滴的破碎过程，获得了雾化压力、熔体过热度等对金属液雾化作用规律，明确了雾化工艺参数与粉末粒度和氧含量的关系，对所制备的合金粉末的微观组织和相组成进行了表征，探明了TiAl合金粉末的氧化特性，以及真空除气等后处理对粉末氧含量的影响，从而为改进TiAl 合金粉末的制备工艺提供科学依据，同时为粉末冶金TiAl合金的研制奠定坚实的理论和试验基础。