【摘要】 以Ar气雾化法制备镍基高温合金粉末,利用选区激光熔化(SLM)技术制备了FGH4096M合金。运用OM、SEM、EBSD等手段研究了SLM沉积态和热处理态合金的组织和性能。结果表明,沉积态合金以奥氏体γ相基体为主,具有最高的延伸率。热处理后合金内析出大量的γ’相,γ’相均匀致密分布于合金内,能够明显提高合金强度。立方状或花瓣状γ’相与基体存在较高的晶格畸变,也能增加合金强度。精细的树枝结构和等轴结构对合金起到细晶强化作用。较高的固溶温度会促进SLM合金内回复和再结晶的发生,同时消除晶内树枝结构和等轴结构。沉积态合金平均延伸率为24.97%。经直接时效处理后的合金屈服强度和极限强度最高,其平均值分别为1459.46和1595.56 MPa。更多还原

【Abstract】 Nickel-based powder metallurgy superalloys have the characteristics of uniform structure,fine grains and no macrosegregation. Due to their excellent mechanical properties, such as excellent fatigue resistance, creep resistance, excellent high-temperature strength and crack propagation resistance,they have become the preferred materials for critical hot-end components such as aero engine turbine disks. Selective laser melting(SLM) has a high ability to form complex shape of parts, reducing postmachining procedures and completing efficient productions with low component volumes, so it has become a new technical route for the preparation of superalloys. In this work, the FGH4096 M alloy was prepared by SLM technique with pre-powders prepared by vacuum induction argon atomization method.The microstructure and mechanical properties of the as build and heat-treated(HTed) alloys were investigated by OM, SEM, EBSD and so on. The as build alloy with a small number of γ’ and carbide, mainly composed of austenite matrix γ phase, has the highest elongation. After heat treatment, a large amount of γ’ phase precipitated in the alloy, which is one of the main factors affecting the mechanical properties of the alloy. The uniform and dense distribution of γ’ precipitates in the alloy can significantly improve the strength. A higher lattice distortion between the γ’ phase with cubic or petaloid shape and matrix can increase the strength of the alloy to some extent. Fine dendritic and equiaxed structures in SLM FGH4096 M can improve the property of the alloy as fine grain strengthening. The higher solution temperature promotes the recovery and recrystallization of the SLM alloy, and eliminates the intra-crystal dendritics and equiaxed structures. The average elongation of the as build alloy is 24.97%. The yield strength and ultimate strength of the SLM FGH4096 M alloy after direct ageing treatment are the highest, and the average values are 1459.46 and 1595.56 MPa, respectively.更多还原