超瞬态凝固增材制造梯度整体涡轮叶盘用高温合金粉末特性研究Ⅱ:叶片用合金粉末

Characteristics of Ni-Based Superalloy Powders Used for the Gradient Integral Turbine Blisk by the Ultra-transient Solidified Additive ManufacturingⅡ:Blade Alloy Powders

对超瞬态凝固增材制造梯度整体涡轮叶盘高温合金叶片用合金粉末特性开展研究。根据合金的承温能力和JMatPro相平衡计算结果,选用DZ4125作为叶片材料,K418作为叶盘轮缘部位材料。采用真空感应熔炼氩气雾化制粉(VIGA)制备DZ4125高温合金粉末,筛分至53~105μm粒度范围,采用差示扫描量热分析(DSC)、场发射扫描电镜(FESEM)和能谱(EDS)、激光粒度仪、动态图像粒度粒形分析仪以及综合粉体性能测试仪对DZ4125高温合金粉末的相变温度、显微组织、析出相成分、元素偏析行为、粒度、粒形、松装密度、振实密度和流动性进行系统表征。结果表明:DZ4125比K418合金的固液凝固温度范围宽,过渡区DZ4125+K418混合成分合金其液相线温度和MC碳化物开始析出温度介于2种合金之间,γ′开始析出温度与2种合金相当。DZ4125合金粉末形貌主要为球形和近球形,表面和截面显微组织主要呈树枝晶结构。所含元素中偏析倾向较强的元素有Hf、Ta、Ti、Mo和W,而偏析倾向弱的元素包括Ni、Co、Cr和Al。粉末内部枝晶间区分布有细小的MC碳化物,尺寸约为200nm。激光衍射和动态图像分析法测得的DZ4125粉末粒度值接近,中位径D50分别为70.2和72.8μm。动态图像法测得DZ4125合金粉末具有较好的球形度,SPHT(球形度)和b/l(长径比)均值分别为0.91和0.86。所选DZ4125高温合金粉末具有较好的松装密度、振实密度和流动性,其松装和振实密度分别达到合金理论密度的52%和63%,压缩度为17.7%,且粉末具有较好的流动性(20.79 s·(50 g)^(-1))。

The characteristics of superalloy powders used for the gradient integral turbine blisk by the ultra-transient solidified additive manufacturing were investigated.According to the temperature capacity of the alloy and the phase equilibrium diagram calculated by JMatPro,DZ4125 was selected as the blade material,whereas K418 alloys were selected as the disk rim material for integral turbine blisk.The superalloy powder were prepared by vacuum induction melting and argon gas atomization(VIGA)and sieved to the particle size range of 53~105μm.The differential scanning calorimeter(DSC),field emission scanning electron microscopy(FESEM),energy dispersive spectroscopy(EDS),laser diffraction particle size analyzer,dynamic image analysis system and comprehensive powder property analyzer were used to systematically characterize the phase transformation temperatures,microstructure,precipitated phase composition,element segregation,particle size and shape,apparent density,tap density and flowability of the selected superalloy powders.The results show that DZ4125 possesses wider solid-liquid temperature range than K418 alloy.The liquidus temperature and MC carbide initial precipitation temperature of the transition zone DZ4125+K418 hybrid composition alloy are between that of the two alloys,and theγ’onset precipitation temperature is equivalent to the two alloys.The morphology of DZ4125 alloy powders is mainly spherical and nearly spherical.The surface and cross-section microstructures are mainly dendritic structure.For the selected alloy powders,the elements Hf,Ta,Ti,Mo and W exhibit strong segregation tendency,while the elements with weak segregation tendency include Ni,Cr,Co and Al.There are fine MC carbides distributed in the interdendritic zone of the powder,and the size is about 200 nm.The particle size distribution of powders measured by laser diffraction and dynamic image analysis methods is similar.The D50 values of DZ4125 powder are 70.2 and 72.8μm.The dynamic image analysis result shows that the DZ4125 alloy powders possess good sphericity,and the SPHT and b/l values are 0.91 and 0.86,respectively.The DZ4125 superalloy powders have good apparent density,tap density and flowablity.The apparent density and tap density of the alloy powders can reach 52%and 63%of the theoretical density of the DZ4125 alloy,respectively.In addition,the DZ4125 superalloy powders possess compressibility of 17.7%and flowability of 20.79 s·(50 g)^(-1).