球形TC4粉末的气雾化制备、表征及间隙元素控制

摘要

The spherical TC4 alloy powders were produced by gas atomization using water-cooled copper crucible and argon gas with high purity.TheY2O3layerwas coatedonto the inner wall of the graphite nozzle. The interstitial level of the gas-atomized powders with various particle sizes was analyzed to investigate the effect of coating. The sources of interstitial content for gas-atomized powderswere also discussed and related suggestions for its control were provided. Besides, the microstructures of gas-atomized powders with various particle sizes were alsocharacterizedin terms of surface morphology and cross-sectional structures. The resultsshow that the Y2O3coatingcaneffectively prevent the gas-atomized powders from carbonization by graphite nozzle as comparingwithorwithout coating. The interstitial component of the gas-atomized TC4 powders increases with the particle size decreasing.The surface of coarse powders exhibits thecellular structure with equiaxed grains. However, the fine powders achieve smooth surfaces andcannot be observed any crystallization.Because ofrapid solidification, bothαcells and acicular martensiteα′ phasesare observed in the internal area of coarse powders, while only honeycomb cellular structureisdemonstrated with refined grains in fine powders.%利用水冷铜坩埚熔炼、高纯氩气雾化技术制备出高品质球形TC4合金粉末。将石墨导流管的内壁用Y2O3与无水乙醇配比的涂料进行涂覆，分析其对雾化粉末间隙元素的影响，总结气雾化粉末的间隙元素来源及控制建议，并对不同粒度粉末的显微组织进行表征。结果表明：石墨导流管内壁在无涂层的情况下，雾化粉末的碳含量较大；而导流管内壁的Y2O3涂层能有效降低碳对钛合金污染的风险；粉末间隙元素含量随着粒径的减小而增大；粒径较大粉末的表面为胞状晶组织，而小尺寸粉末表面光滑且无明显结晶组织；由于快速凝固的原因，粒径较大粉末的内部主要由α相胞晶和针状马氏体α′相组成，小粒径粉末的内部组织明显细化，全部为蜂窝状的胞状晶组织。