粉末注射成形制备复杂薄壁TiAl合金旋流器  

Preparation of complex thin-walled TiAl alloy swirlers by powder injection molding

作　　者：刘艳军 潘宇 孙健卓 朱郎平 丁贤飞 南海 路新 LIU Yanjun;PAN Yu;SUN Jianzhuo;ZHU Langping;DING Xianfei;NAN Hai;LU Xin(Institute of Engineering Technology,University of Science and Technology Beijing,Beijing 102206,China;AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China;Beijing Advanced Innovation Center for Materials Genome Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学工程技术研究院,北京102206 [2]中国航发北京航空材料研究院,北京100095 [3]北京科技大学北京材料基因工程高精尖创新中心,北京100083

出　　处：《材料工程》2024年第12期67-79,共13页Journal of Materials Engineering

基　　金：中国航空发动机集团产学研合作项目(HFZL2021CXY021)。

摘　　要：旋流器作为航空发动机的重要部件,实现其轻量化制造对提升发动机服役性能具有重要意义。轻质高强耐热TiAl合金是一种极具应用潜力的高温结构材料,但其本征脆性大、制备加工困难,严重限制其在高性能旋流器制造方面的应用。为此,本研究采用粉末注射成形(powder injection molding,PIM)制备方法,结合水溶性芯模的模具设计及高保形聚甲醛(POM)基黏结剂开发,通过催化脱脂、热脱脂及两步烧结工艺,直接近净成形制备出复杂薄壁TiAl合金旋流器,无需机加工过程。结果表明:成分为82%(质量分数,下同)POM-5%高密度聚乙烯(HDPE)-5%乙烯-醋酸乙烯共聚物(EVA)-8%硬脂酸(SA)的黏结剂具有较高的粉末装载量和较佳的充模性能,其喂料粉末装载量为62%(体积分数),流动行为指数n为0.56,黏流活化能E为22.95 kJ/mol,综合流变学因子为9.59;常压两步烧结方法可实现高致密度和细晶的协同控制,当烧结工艺为1430℃/1 h+1250℃/5 h时,PIM所制备TiAl合金的致密度达到96.3%,且片层团尺寸约为100μm,后续结合热等静压处理实现了TiAl合金的近全致密化,所制备复杂薄壁TiAl合金旋流器的尺寸偏差为±0.1 mm,表面粗糙度Ra为1.046μm,室温抗拉强度为577 MPa,屈服强度为466 MPa,伸长率为0.96%。As an important component of aeroengines,the lightweight manufacturing of swirlers is of great significance for improving the service performance of engines.Lightweight,high-strength,and heatresistant TiAl alloy is a high-temperature structural material with great application potential,but its inherent brittleness and difficulty in preparation and processing seriously limit its application in the fabrication of high-performance swirlers.Therefore,the powder injection molding(PIM)technology was used to prepare the complex thin-walled TiAl alloy swirlers in near-net shape without any machining process by combining the mold design method of water-soluble core and high conformal polyformaldehyde(POM)-based binders.The preparation processes mainly include catalytic debinding,thermal debinding,and two-step sintering.The results show that the binder with a composition of 82%(mass fraction,the same below)POM-5%high density polyethylene(HDPE)-5%ethylene-vinyl acetate copolymer(EVA)-8%stearic acid(SA)has a higher powder loading and better molding filling performance.The powder loading,the flow behavior index n,the viscous flow activation energy E,and the general rheological indexαSTV of the feedstock are 62%(volume fraction),0.56,22.95 kJ/mol,and 9.59,respectively.The two-step sintering method under pressureless can achieve synergistic control of high relative density and fine grain.When the sintering process is set to 1430℃/1 h+1250℃/5 h,the relative density of PIM TiAl alloy reaches 96.3%with a lamellar colony size of about 100μm.After hot isostatic pressing(HIP)treatment,nearly complete densification of the TiAl alloy is achieved,and the dimensional deviation and surface roughness Ra of the prepared swirlers are±0.1 mm and 1.046μm,respectively.The room-temperature tensile strength,yield strength,and elongation of the HIP TiAl alloy are 577,466 MPa,and 0.96%,respectively.

关 键 词：TIAL合金 旋流器 粉末注射成形 尺寸精度 表面粗糙度 力学性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程] TB31[金属学及工艺—金属材料]