凝胶注模成形Ti6Al4V钛合金的组织和性能研究

目的 为了实现低成本、低能耗、高效率制备大尺寸复杂形状钛合金的问题,以凝胶注模技术为成形手段,制备近净成形Ti6Al4V合金,并研究其组织及性能.方法 通过溶液包覆法,在Ti6Al4V钛合金球形粉末表面包覆石蜡(PW),分析有机包覆层在凝胶注模过程中的作用机制及流变行为的影响,测定包覆前后不同粉末进行凝胶注模烧结后的组织及性能,得到该方法 对减少钛合金凝胶注模的碳氧残留的效果并进行原理分析.结果 经质量分数为0.36％的石蜡包覆后,烧结样品中碳的质量分数从0.5433％下降到0.2841％,氧的质量分数从0.3859％下降到0.3178％;烧结样品的相对密度从93.6％提高到97.5％.此外,烧结后的试样也具有较好的综合力学性能,抗拉强度为1129 MPa,屈服强度为1015 MPa,伸长率为5.18％.结论 凝胶注模成形技术在制造低成本、形状复杂、性能优异的钛合金零件方面具有良好的应用前景.

Microstructure and Performance of Gelcasting Ti6Al4V Alloys

The work aims to prepare near-net forming Ti6Al4V alloy by gelcasting technology and study its microstructure and performance to prepare large-sized and complex-shaped titanium (Ti) alloy with low cost, low energy consumption and high efficiency. Ti6Al4V powder surface was coated with paraffin wax (PW) using solution. The influences of action mechanism and rheological behavior of PW coating in gelcasting process were investigated. The microstructure and performance of the uncoated and coated gelcasted samples were analyzed. The effect and mechanism of PW coating on carbon and oxygen residual of the gelcasted Ti alloy were clarified. With 0.36% PW addition, the carbon and oxygen contents of as-sintered sample decreased from 0.5433% to 0.2841% and from 0.3859% to 0.3178%, respectively. The relative density of the as-sintered sample increased from 93.6% to 97.5%. Besides, the as-sintered sample also exhibited better comprehensive mechanical properties, about 1129 MPa of tensile strength, 1015 MPa of yield strength, and 5.18% of elongation. Gelcasting technology shows good application prospects for fabricating complex-shaped and high-performance Ti parts with low cost.